tag:theconversation.com,2011:/us/topics/rem-sleep-19414/articlesREM sleep – The Conversation2024-02-29T21:48:23Ztag:theconversation.com,2011:article/2228542024-02-29T21:48:23Z2024-02-29T21:48:23ZBetter sleep is a protective factor against dementia<figure><img src="https://images.theconversation.com/files/573581/original/file-20240117-23-vqzz7m.jpg?ixlib=rb-1.1.0&rect=60%2C0%2C6720%2C4456&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Lack of sleep, or poor quality sleep, is one of the risk factors for developing Alzheimer's disease. Fortunately, there are ways to improve sleep.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Dementia is a progressive loss of cognitive abilities, such as memory, that is significant enough to have an impact on a person’s daily activities. </p>
<p>It can be caused by a number of different diseases, including <a href="https://alzheimer.ca/en/about-dementia/what-alzheimers-disease">Alzheimer’s</a>, which is the most common form. Dementia is caused by a loss of neurons over a long period of time. Since, by the time symptoms appear, many changes in the brain have already occurred, many scientists are focusing on studying the risk and protective factors for dementia. </p>
<p>A risk factor, or conversely, a protective factor, is a condition or behaviour that increases or reduces the risk of developing a disease, but does not guarantee either outcome. Some risk factors for Alzheimer’s disease and dementia, such as age or genetics, are not modifiable, but there are several other factors we can influence, <a href="https://www.thelancet.com/article/S0140-6736(20)30367-6/fulltext">specifically lifestyle habits and their impact on our overall health</a>.</p>
<p>These risk factors include depression, lack of physical activity, social isolation, high blood pressure, obesity, diabetes, excessive alcohol consumption and smoking, as well as poor sleep.</p>
<p>We have been focusing our research on the question of sleep for over 10 years, particularly in the context of the <a href="https://www.nhlbi.nih.gov/science/framingham-heart-study-fhs">Framingham Heart Study</a>. In this large community-based cohort study, ongoing since the 1940s, the health of surviving participants has been monitored to the present day. As researchers in sleep medicine and epidemiology, we have expertise in researching the role of sleep and sleep disorders in cognitive and psychiatric brain aging. </p>
<p>As part of our research, we monitored and analyzed the sleep of people aged 60 and over to see who did — or did not — develop dementia. </p>
<h2>Sleep as a risk or protective factor against dementia</h2>
<p>Sleep appears to play an essential role in a number of brain functions, such as memory. Good quality sleep <a href="https://jamanetwork.com/journals/jamaneurology/fullarticle/2793873">could therefore play a vital role in preventing dementia</a>.</p>
<p>Sleep is important for maintaining <a href="https://www.science.org/doi/10.1126/science.1241224">good connections in the brain</a>. Recently, research has revealed that sleep seems to have a function similar to that of a garbage truck for the brain: <a href="https://doi.org/10.1016/j.mad.2023.111899">deep sleep could be crucial for eliminating metabolic waste from the brain</a>, including clearing certain proteins, such as those known to accumulate in the brains of people with Alzheimer’s disease. </p>
<p>However, the links between deep sleep and dementia still have to be clarified.</p>
<h2>What is deep sleep?</h2>
<p>During a night’s sleep, we go through several <a href="http://ceams-carsm.ca/en/a-propos-du-sommeil/">sleep stages</a> that succeed one another and are repeated. </p>
<p>NREM sleep (non-rapid eye movement sleep) is divided into light NREM sleep (NREM1 stage), NREM sleep (NREM2 stage) and deep NREM sleep, also called slow-wave sleep (NREM3 stage). The latter is associated with several restorative functions. Next, REM sleep (rapid eye movement sleep) is the stage generally associated with the most vivid dreams. An adult generally spends around 15 to 20 per cent of each night in deep sleep, if we add up all the periods of NREM3 sleep. </p>
<p>Several sleep changes are common in adults, such as going to bed and waking up earlier, sleeping for shorter periods of time and less deeply, and waking up more frequently during the night.</p>
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<a href="https://images.theconversation.com/files/579041/original/file-20240229-16-efo9mx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/579041/original/file-20240229-16-efo9mx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579041/original/file-20240229-16-efo9mx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=279&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579041/original/file-20240229-16-efo9mx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=279&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579041/original/file-20240229-16-efo9mx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=279&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579041/original/file-20240229-16-efo9mx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=350&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579041/original/file-20240229-16-efo9mx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=350&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579041/original/file-20240229-16-efo9mx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=350&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Sleep stages, and the role of deep sleep for brain health.</span>
<span class="attribution"><span class="source">(Andrée-Ann Baril)</span></span>
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<h2>Loss of deep sleep linked to dementia</h2>
<p>Participants in the <a href="https://jamanetwork.com/journals/jamaneurology/fullarticle/2810957">Framingham Heart Study</a> were assessed using a sleep recording — known as polysomnography — on two occasions, approximately five years apart, in 1995-1998 and again in 2001-2003. </p>
<p>Many people showed a reduction in their deep slow-wave sleep over the years, as is to be expected with aging. Conversely, the amount of deep sleep in some people remained stable or even increased. </p>
<p>Our team of researchers from the Framingham Heart Study followed 346 participants aged 60 and over for a further 17 years to observe who developed dementia and who did not. </p>
<p>Progressive loss of deep sleep over time was associated with an increased risk of dementia, whatever the cause, and particularly Alzheimer’s type dementia. These results were independent of many other risk factors for dementia.</p>
<p>Although our results do not prove that loss of deep sleep causes dementia, they do suggest that it could be a risk factor in the elderly. Other aspects of sleep may also be important, such as its duration and quality. </p>
<h2>Strategies to improve deep sleep</h2>
<p>Knowing the impact of a lack of deep sleep on cognitive health, what strategies can be used to improve it? </p>
<p>First and foremost, if you’re experiencing sleep problems, it’s worth talking to your doctor. Many sleep disorders are underdiagnosed and treatable, particularly through behavioural (i.e. non-medicinal) approaches. </p>
<p>Adopting good sleep habits can help, such as going to bed and getting up at consistent times or avoiding bright or blue light in bed, like that of screens. </p>
<p>You can also avoid caffeine, limit your alcohol intake, maintain a healthy weight, be physically active during the day, and sleep in a comfortable, dark and quiet environment.</p>
<p>The role of deep sleep in preventing dementia remains to be explored and studied. Encouraging sleep with good lifestyle habits could have the potential to help us age in a healthier way.</p><img src="https://counter.theconversation.com/content/222854/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrée-Ann Baril received funding from the Sleep Research Society Foundation, the Alzheimer Society of Canada, the Canadian Institutes of Health Research, Banting Postdoctoral Fellowships, the Fondation de l'Hôpital du Sacré-Coeur de Montréal, the Université de Montréal and speaking fees from Eisai.</span></em></p><p class="fine-print"><em><span>Matthew Pase received funding from the National Health and Medical Research Council of Australia, National Institute on Aging, Dementia Australia, Alzheimer's Association, National Heart Foundation of Australia, Australian Research Council, Stroke Foundation, Brain Foundation, Alzheimer's Drug Discovery Foundation, Rebecca L Cooper Medical Research Foundation, and Bethlehem Griffiths Research Foundation.</span></em></p>Sleep appears to play an essential role in a number of brain functions, such as memory. So good quality sleep could play a vital role in preventing dementia.Andrée-Ann Baril, Professeure-chercheure adjointe au Département de médecine, Université de MontréalMatthew Pase, Associate Professor of Neurology and Epidemiology, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2241312024-02-26T17:24:36Z2024-02-26T17:24:36ZInsomnia: how chronic sleep problems can lead to a spiralling decline in mental health<figure><img src="https://images.theconversation.com/files/577722/original/file-20240224-24-su6ra5.jpg?ixlib=rb-1.1.0&rect=21%2C142%2C3629%2C2310&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/man-insomnia-cannot-sleep-hand-drawn-1965734296">APIMerah/Shutterstock</a></span></figcaption></figure><blockquote>
<p>I’ll often lie awake until three or four in the morning, before drifting off for just a few hours. Then comes the dreaded alarm clock. My mind and body are exhausted all the time – there’s always this knot of anxiety in my chest, doing away with any hope of a good night’s sleep.</p>
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<p>Simon* is a NHS mental health nurse who, like millions of people in the UK, suffers from insomnia: a sustained difficulty in initiating and maintaining sleep. His job is to support the recovery of people with severe mental illness, but his own sleep problems have had a profoundly negative impact on his mental health.</p>
<p>Most of us experience a bad night’s sleep from time to time, but can usually get back on track within a night or two. People suffering from insomnia, by contrast, have sleep problems that last for months or years at a time, taking a major toll on their health and wellbeing.</p>
<p>Around <a href="https://jcsm.aasm.org/doi/10.5664/jcsm.26929#:%7E:text=a%20cognitive%20system.-,CONCLUSION,%2C%20social%2C%20and%20physical%20domains.">a third</a> of people will experience insomnia at some point in their life, with women and older people more often affected. Nearly 40% of sufferers <a href="https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2772563">fail to recover within five years</a>. People with insomnia have an increased risk of diabetes, high blood pressure and <a href="https://www.sciencedirect.com/science/article/abs/pii/S1556407X22000182?via%3Dihub">cardiovascular disease</a>. Insomnia is also a major risk factor for <a href="https://onlinelibrary.wiley.com/doi/10.1111/jsr.13628">mental illness</a>, and often co-occurs with mood disorders such as depression and anxiety.</p>
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<p><em>Across the world, we’re seeing unprecedented levels of mental illness at all ages, from children to the very old – with huge costs to families, communities and economies. <a href="https://theconversation.com/uk/topics/tackling-the-mental-health-crisis-147216?utm_source=TCUK&utm_medium=ArticleTop&utm_campaign=MentalHealthSeries">In this series</a>, we investigate what’s causing this crisis, and report on the latest research to improve people’s mental health at all stages of life.</em></p>
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<p>Many different life events can increase your chances of sustained sleep deprivation. Both the financial burden and confinement arising from the COVID-19 pandemic were associated with <a href="https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-022-14048-1">greater risk</a> of insomnia, which is in turn likely to have led to a <a href="https://www.sciencedirect.com/science/article/pii/S1389945721004196?via%3Dihub">rise in mental health problems</a>.</p>
<p>And yet, very little is known about why and how a prolonged absence of sleep gives rise to mental illness. Our team at the University of York has pioneered research into whether sleep deprivation <a href="https://www.sciencedirect.com/science/article/pii/S1364661321000577">disrupts the brain’s ability to suppress intrusive memories</a> and distressing thoughts – classic symptoms of psychiatric disturbance. </p>
<p>It has also led us to ask whether it might one day be possible to treat mental illness while patients are sleeping – for example, by using sounds to normalise irregular patterns of brain activity during rapid eye movement (REM) sleep.</p>
<h2>Why are some people so badly affected?</h2>
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<p>They put their hand over my face so I couldn’t breathe. Now I can’t wear anything that covers my mouth or nose for fear of reliving [that experience]. Mask wearing was a big problem for me during the pandemic – and it was always worse when I slept badly. Just the sight of other people wearing masks could bring it all back.</p>
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<p>Helen* is a domestic abuse survivor who suffers from post-traumatic stress disorder (PTSD), a debilitating condition characterised by flashbacks, nightmares and severe anxiety. She told us her symptoms would always get worse after a bad night’s sleep – a pattern reported by other PTSD sufferers we spoke to.</p>
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<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/insomnia-concept-young-woman-sitting-her-625713866">Randoms/Shutterstock</a></span>
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<p>We can all sometimes encounter intrusive and unwanted thoughts, usually in response to reminders – for example, seeing a former partner and being reminded of an unpleasant breakup. While unsettling, these thoughts are infrequent, short-lived and, usually, quickly forgotten. This is in stark contrast to the highly lucid, distressing thoughts experienced by people with PTSD. Sufferers often engage in avoidant behaviour, such as not leaving home to reduce the likelihood of having to confront reminders of their trauma. </p>
<p>However, the symptoms of PTSD can also partly be explained by a breakdown of the brain mechanisms we rely on to push such intrusive thoughts out of conscious awareness. Because intrusive thoughts arise from unpleasant memories, another way people ward them off is by suppressing the offending content from their memory. But PTSD sufferers often <a href="https://journals.sagepub.com/doi/10.1177/0956797615569889">exhibit a deficit</a> in their ability to engage in this process of memory suppression, resulting in persistent unwanted patterns of thinking.</p>
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<img alt="" src="https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/288776/original/file-20190820-170910-8bv1s7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>This article is part of Conversation Insights</em></strong>
<br><em>The Insights team generates <a href="https://theconversation.com/uk/topics/insights-series-71218">long-form journalism</a> derived from interdisciplinary research. The team is working with academics from different backgrounds who have been engaged in projects aimed at tackling societal and scientific challenges.</em></p>
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<p>And what if lack of sleep reduces our ability to suppress unwanted thoughts and memories? This could lead to a downward spiral of more persistent and frightening intrusive thoughts, severe anxiety, and chronic sleeplessness – culminating in psychiatric disturbance.</p>
<p>Although a <a href="https://www.nature.com/articles/nrn.2017.55">wealth of research</a> has shown that sleep deprivation leads to psychological instability, <a href="https://journals.sagepub.com/doi/10.1177/2167702620951511">our study</a> was the first study to examine how an inability to control intrusive thoughts might underpin this relationship. For this reason, we worked with young adults without a diagnosed mental health disorder, allowing us to determine how even healthy brain processes go awry when people do not get enough sleep.</p>
<h2>How sleep deprivation affects our brain</h2>
<p>Our group of young adults (aged 18–25) were asked to memorise face-image pairs, comprising a male or female face with a neutral expression next to a unique scene. They would memorise each pair over and over again, so that any face presented in isolation would serve as a powerful reminder of the scene it was paired with – in the same way a reminder of an unpleasant event in the real world can trigger a distressing thought.</p>
<p>The face-scene learning took place late in the evening – after which half the participants went to sleep in our laboratory, and the other half stayed awake for the entire night – watching movies, playing games and going for short walks outside. They could eat and drink, but psychological stimulants such as caffeine were strictly prohibited. We would wake anyone in this group who nodded off.</p>
<p>Next morning, all participants were shown the faces only, in random order, with the following instructions. If the face was inside a green frame, the participant should allow the associated scene to come into their mind. A red frame meant they should engage in memory suppression to block out the scene – in the same way we sometimes purge unwanted thoughts from our conscious experience.</p>
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<a href="https://images.theconversation.com/files/577966/original/file-20240226-24-8ldt9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Explanation of face-image sleep and memory suppression experiment." src="https://images.theconversation.com/files/577966/original/file-20240226-24-8ldt9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/577966/original/file-20240226-24-8ldt9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=445&fit=crop&dpr=1 600w, https://images.theconversation.com/files/577966/original/file-20240226-24-8ldt9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=445&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/577966/original/file-20240226-24-8ldt9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=445&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/577966/original/file-20240226-24-8ldt9l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=560&fit=crop&dpr=1 754w, https://images.theconversation.com/files/577966/original/file-20240226-24-8ldt9l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=560&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/577966/original/file-20240226-24-8ldt9l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=560&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Sleep and memory suppression experiment.</span>
<span class="attribution"><a class="source" href="https://www.epoc-york.com/research">Scott Cairney/University of York</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
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<p>Our sleep-deprived participants reported having more “intrusions” (failed memory suppression attempts) than those who had slept normally. And only well-rested participants got better at suppressing the unwanted memories over time. This suggests that sleeplessness does long-term harm to our ability to suppress intrusive memories and, hence, unwanted thoughts.</p>
<p>What’s going wrong inside a sleep-deprived person’s brain? To address this question, we <a href="https://www.biorxiv.org/content/10.1101/2023.11.07.565941v1">repeated our study</a>, but this time with participants undergoing <a href="https://www.ndcn.ox.ac.uk/divisions/fmrib/what-is-fmri/introduction-to-fmri">functional magnetic resonance imaging</a> (fMRI) – a powerful neuroimaging technique that allows us to determine which brain regions are engaged during particular cognitive operations (in this case, keeping intrusive memories at bay).</p>
<p>Memory suppression <a href="https://www.sciencedirect.com/science/article/pii/S1364661314000746?via%3Dihub">relies on a brain region</a> known as the right <a href="https://en.wikipedia.org/wiki/Dorsolateral_prefrontal_cortex">dorsolateral prefrontal cortex</a> (rDLPFC). When a reminder triggers retrieval of an unwanted memory, the rDLPFC inhibits activity in the brain’s memory processing centre, the <a href="https://en.wikipedia.org/wiki/Hippocampus">hippocampus</a>, to push that memory out of the person’s mind.</p>
<p>Our fMRI study showed that, when participants were attempting to suppress unwanted memories, activity in rDLPFC was reduced after a night of sleep deprivation relative to a night of restful sleep. Moreover, activity in the hippocampus was stronger after sleep deprivation than restful sleep, suggesting that a breakdown of control by rDLPFC had allowed unsolicited memory operations to emerge with impunity, opening the door to intrusive patterns of thinking.</p>
<h2>Can better sleep improve our mental health?</h2>
<p>REM sleep, discovered by <a href="https://www.science.org/doi/10.1126/science.118.3062.273">Eugene Aserinsky and Nathaniel Kleitman</a> in 1953, is a unique stage of sleep characterised by rapid movement of the eyes and a high propensity for vivid dreaming.</p>
<p>As the brain enters REM sleep, it undergoes dramatic changes that are thought to play an important role in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2890316/">regulating our mental health</a>. For example, levels of the neurotransmitter <a href="https://www.britannica.com/science/acetylcholine">acetylcholine</a>, which modulates the processing of disturbing memories, are markedly increased in REM sleep relative to other sleep stages, mirroring levels seen in wakefulness. Abnormalities of REM sleep are <a href="https://www.annualreviews.org/doi/10.1146/annurev-clinpsy-032813-153716">linked</a> to various psychiatric mood disorders including PTSD, and associated with the intense nightmares experienced following trauma.</p>
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Read more:
<a href="https://theconversation.com/a-short-history-of-insomnia-and-how-we-became-obsessed-with-sleep-211729">A short history of insomnia and how we became obsessed with sleep</a>
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<p>So, could the brain mechanisms that allow us to control intrusive memories be especially influenced by the amount of REM sleep we obtain over the course of a night? To investigate this, our fMRI study included <a href="https://pubmed.ncbi.nlm.nih.gov/31277862/">polysomnography</a> – a sleep monitoring technique that enabled us to identify when participants were in REM sleep, based on both their eye movement and discrete brainwave patterns.</p>
<p>Among our participants who slept, those who had more REM sleep showed stronger engagement of their rDLPFC when suppressing unwanted memories the next morning. This suggests REM sleep may indeed support mental health by restoring the brain systems that help to shield us from unwelcome thoughts.</p>
<h2>The emotional intensity of our memories</h2>
<p>When we think back to a traumatic or painful life event, we get a sense of the unpleasant feelings, such as sadness or anger, that accompanied the original experience. However, the intensity of these feelings is usually much reduced, allowing us to draw on past events without being consumed by negative emotions.</p>
<p>Suppressing unwanted thoughts has been shown to <a href="https://elifesciences.org/articles/71309">weaken the memories</a> that lead to them, meaning they are less likely to intrude into our consciousness in the future. This relates not only to the content of the memories (the “what, when and who”) but also <a href="https://www.jneurosci.org/content/37/27/6423.long">their emotional charge</a> – the intensity of the emotions we felt at the time. In other words, memory suppression helps us move on from prior adversity by gradually cleansing our memories of unpleasant experiences, and the negative emotions associated with them.</p>
<p>Conversely, failing to suppress an unwanted memory is likely to cause its emotional charge to linger, meaning that emotional responses to future reminders will remain more intense. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/577728/original/file-20240224-16-qbm7dc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of exhausted man in bed, suffering with insomnia" src="https://images.theconversation.com/files/577728/original/file-20240224-16-qbm7dc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/577728/original/file-20240224-16-qbm7dc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=425&fit=crop&dpr=1 600w, https://images.theconversation.com/files/577728/original/file-20240224-16-qbm7dc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=425&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/577728/original/file-20240224-16-qbm7dc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=425&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/577728/original/file-20240224-16-qbm7dc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=534&fit=crop&dpr=1 754w, https://images.theconversation.com/files/577728/original/file-20240224-16-qbm7dc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=534&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/577728/original/file-20240224-16-qbm7dc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=534&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/man-insomnia-cannot-sleep-hand-drawn-1819333274">APIMerah/Shutterstock</a></span>
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<p>We tested this by showing our participants scenes that were either emotionally negative (such as a car crash) or neutral (such as a forest). In the morning, after completing the memory retrieval and suppression task (with green and red-framed faces), participants were then asked to give intensity ratings for the negative and neutral scenes again.</p>
<p>Our findings were clear – and corroborated by further tests using an objective index of emotional arousal, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2695635/#:%7E:text=The%20skin%20conductance%20response%20(SCR)%20is%20an%20indirect%20measure%20of,emotional%20valence%20(Bradley%20et%20al.)">skin conductance responses</a>. Among participants who had slept, emotional responses to the suppressed negative scenes became less intense over time. But among the sleep-deprived, emotional ratings for negative scenes remained elevated, regardless of whether the scenes were suppressed or not. This suggests that a breakdown of memory suppression mechanisms after sleep loss prevented participants from being able to “deal with” these negative emotions.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/insomnia-and-mental-disorders-are-linked-but-exactly-how-is-still-a-mystery-212106">Insomnia and mental disorders are linked. But exactly how is still a mystery</a>
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</em>
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<p>In the context of psychiatric mood disorders that co-occur with chronic sleep disturbance, failure to suppress memories of emotionally disturbing events, together with an inability to reduce the unpleasant feelings embedded within those memories, could contribute to a strong tendency of mood-disordered individuals to focus on negative interpretations of the past.</p>
<p>Furthermore, anxiety arising from intrusive memories may also obstruct the sleep that is needed for recovery, leading to a vicious cycle of emotional dysregulation and sleeplessness.</p>
<h2>The importance of forgetting</h2>
<p>In the film Eternal Sunshine of the Spotless Mind (2004), the main characters have their memories of their turbulent relationship erased. Far from improving their quality of life, this leads to further complications, serving as a cautionary tale. </p>
<p>However, there are situations where aiding the forgetting process may help. For example, people who have experienced traumatic experiences can struggle to cope with unwanted memory intrusions. In these extreme cases, where the usual brain processes that allow for forgetting aren’t functioning properly, it could be beneficial to induce forgetting.</p>
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<p>Generally, forgetting is thought of as “bad”, with people worrying about forgetting where they put the car keys, or when their wedding anniversary is. But far from being a problem, this is how <a href="https://theconversation.com/why-forgetting-is-a-normal-function-of-memory-and-when-to-worry-223284">memory is supposed to work</a>. Sometimes, we want to just forget information that isn’t relevant to our daily lives, to prevent it from interfering with our goals. And sometimes, we want to forget embarrassing or emotionally scarring events.</p>
<p>Ultimately, the purpose of a functioning memory system is to make sensible and accurate decisions in the present, based on our past experience. The “adaptive” nature of forgetting allows us to get rid of irrelevant memories, making sure the memories that remain are as relevant to future decisions as possible. From this perspective, forgetting is as important as remembering. Simply put, forgetting is a feature of memory, not a bug.</p>
<p>While forgetting is a catch-all term we use for the loss of a memory, it isn’t a single process in the brain. Memories can be forgotten via active processes, such as memory suppression. But this can also happen via passive processes including “decay”, where the physical trace of a memory in the brain breaks down over time, or “interference”, where new memories that are similar to previous ones lead to confusion-impaired retrieval. For example, if you park your car in a new location in the supermarket you often visit, you might forget this new location because the usual place you park comes more readily to mind.</p>
<p>Forgetting is a complex phenomenon that unfolds over different timescales and via different processes, both while awake and asleep. While some memories can fragment, others are forgotten as a whole, so that all aspects of the memory are <a href="https://psycnet.apa.org/fulltext/2019-38883-001.html">no longer accessible</a>. </p>
<p>That forgetting is likely to occur during sleep has been underappreciated by psychologists, because research on sleep has largely focused on the role it plays in strengthening memories. But <a href="https://learnmem.cshlp.org/content/29/11/401.long">we</a> and <a href="https://www.jneurosci.org/content/37/3/464">other researchers</a> have recently reasoned that if forgetting is a fundamental part of a functioning memory system, then sleep should play as much of a role in forgetting as it does in retention.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/577727/original/file-20240224-16-ist89m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of sleep-deprived man in bed, covering his head with pillows." src="https://images.theconversation.com/files/577727/original/file-20240224-16-ist89m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/577727/original/file-20240224-16-ist89m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=405&fit=crop&dpr=1 600w, https://images.theconversation.com/files/577727/original/file-20240224-16-ist89m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=405&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/577727/original/file-20240224-16-ist89m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=405&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/577727/original/file-20240224-16-ist89m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=509&fit=crop&dpr=1 754w, https://images.theconversation.com/files/577727/original/file-20240224-16-ist89m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=509&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/577727/original/file-20240224-16-ist89m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=509&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/man-insomnia-cannot-sleep-hand-drawn-1936830988">APIMerah/Shutterstock</a></span>
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<p>Previous <a href="https://www.science.org/doi/10.1126/science.1179013?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed">research</a>, including <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(18)30153-2">our own</a>, has shown that the presentation of specific sounds during sleep can boost memory. If you were to learn the location of a cat on a computer screen, and during learning we played a “meow” sound, the presentation of the same sound during sleep would lead to better location memory following sleep. This selective boosting of a specific memory during sleep is called “targeted memory reactivation”.</p>
<p>We have <a href="https://learnmem.cshlp.org/content/29/11/401.long">recently shown</a> that this technique can also be used to induce “selective forgetting”. We asked our participants to learn pairs of words or names before going to sleep. We used famous names, location and object words to allow participants to create vivid images in their minds for each pair, so they would be more likely to remember them after a night’s sleep.</p>
<p>But we also made sure the pairs overlapped by sharing one common word. When people learn these overlapping pairs, they compete against each other, and this competition can lead to <a href="https://psycnet.apa.org/record/1995-04358-001">forgetting</a> some of the words. We thought a similar forgetting effect might be seen by using targeted memory reactivation when participants were sleeping. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-forgetting-is-a-normal-function-of-memory-and-when-to-worry-223284">Why forgetting is a normal function of memory – and when to worry</a>
</strong>
</em>
</p>
<hr>
<p>We found the presentation of the word during sleep caused reactivation and strengthening for one pair, but this had a disruptive effect for the other pair. This suggests we could use targeted memory reactivation to selectively strengthen and weaken memories during sleep, presuming we can create interference between two memories. This could be beneficial in the case of people whose brain processes aren’t functioning properly, not allowing them to “healthily forget” disturbing and intrusive memories.</p>
<p>Although such a treatment is still a long way off, our work raises the possibility of using sound cues during sleep – in combination with psychological techniques such as cognitive behavioural therapy – to decrease the crippling emotional grip a particular memory has on a patient.</p>
<h2>Modifying REM sleep to improve mental health</h2>
<p>Given the strong link between REM sleep and mental health disorders, REM sleep may represent a powerful therapeutic target for treating and preventing various psychiatric conditions. By delivering sounds in synchrony with naturally occurring brain rhythms, it is possible to modify patterns of brain activity that are associated with memory processing in REM sleep.</p>
<p>In <a href="https://academic.oup.com/sleep/article/44/4/zsaa227/5960115">one study</a>, we used a computerised algorithm to track rapidly emerging patterns of brain activity in real time while people were asleep (based on polysomnography data). When the algorithm detects the emergence of a particular brain rhythm, it delivers short bursts of sound to increase the intensity of that brain rhythm (akin to pushing a swing as it reaches the highest point of its cycle).</p>
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<p>We have showed this technique can be used to modify distinct brain rhythms in REM sleep. In future, such auditory stimulation could potentially provide a means of renormalising aberrant patterns of brain activity in REM sleep to treat psychiatric disturbance. For example, by integrating this technology with devices that are already available for people to monitor their sleep at home, the playing of particular sounds while someone is sleeping could provide a simple and cost-effective therapy for reducing mood disturbance.</p>
<p>However, this is a long way from being a reality, and many studies would be required to evaluate the feasibility of such an approach before it could be used as a therapeutic tool.</p>
<h2>Targeting sleep in psychiatric hospitals</h2>
<blockquote>
<p>High-risk patients undergo routine observations, sometimes as regularly as every ten minutes, all night and every night. Torches are shone into their rooms – to check they’re breathing – and there’s a lot of noise as doors are open and closed. It has a terrible impact on their sleep.</p>
</blockquote>
<p>Heather* is a consultant forensic psychiatrist who works on a secure mental health ward in the North of England. She describes how the ward regime (in this case, routine welfare checks on high-risk individuals performed throughout the night) impact on patients’ sleep.</p>
<p>A number of people with severe mental illness receive treatment in secure inpatient units. Although the goal of these psychiatric hospitals is to provide a therapeutic setting to support the improvement of mental health, many features of the inpatient environment, such as noise at night or the ward regime, can worsen patients’ sleep disturbances – intensifying the symptoms of their illness, including low mood, impulsivity and aggression.</p>
<p>At the same time, chronic sleeplessness often reduces patients’ engagement with psychological therapies (due to them sleeping in the day or lacking motivation), lengthening their admission and recovery time.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/577726/original/file-20240224-22-trso72.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of a man sitting up in bed, suffering with insomnia" src="https://images.theconversation.com/files/577726/original/file-20240224-22-trso72.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/577726/original/file-20240224-22-trso72.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/577726/original/file-20240224-22-trso72.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/577726/original/file-20240224-22-trso72.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/577726/original/file-20240224-22-trso72.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=535&fit=crop&dpr=1 754w, https://images.theconversation.com/files/577726/original/file-20240224-22-trso72.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=535&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/577726/original/file-20240224-22-trso72.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=535&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/man-insomnia-cannot-sleep-hand-drawn-1964955184">APIMerah/Shutterstock</a></span>
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<p>In a recent international scoping review, we found that only a small number of non-pharmacological sleep interventions had been tested in psychiatric inpatient settings, despite <a href="https://www.medrxiv.org/content/10.1101/2023.03.03.23286483v1">clear evidence</a> that these improve both sleep and mental health outcomes.</p>
<p>New digital technologies can give a clear indication of patient welfare without the need for the noise and disruption Heather describes, providing an environment that is more conducive to healthy sleep. Future studies could test the potential for integrating these digital technologies with sleep-based therapies to speed up recovery times.</p>
<p>Achieving this goal is not only contingent on more research, but also on the capacity for carrying out scientific studies at scale. For example, all of the studies we have described were performed in tightly controlled laboratory environments, usually involving large and expensive pieces of equipment (for example, polysomnography systems). Though <a href="https://journals.sagepub.com/doi/10.1177/0956797619873344?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed">recent efforts have shown promise</a> in the feasibility of moving these techniques into people’s homes, much more work needs to be done outside of the lab before digitised, sleep-focused interventions for mental illness become a reality.</p>
<p>We envisage a future in which sleep is a routine target for reducing or preventing symptoms of mental illness, both in psychiatric inpatient settings and in people’s homes. Although there is much work still to do, sleep research is at an exciting juncture between bench and bedside, and offers a viable solution to the growing global burden of mental illness.</p>
<p><em>*Some names in this article have been changed to protect the anonymity of the interviewees.</em></p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=112&fit=crop&dpr=1 600w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=112&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=112&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=140&fit=crop&dpr=1 754w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=140&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/313478/original/file-20200204-41481-1n8vco4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=140&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em>For you: more from our <a href="https://theconversation.com/uk/topics/insights-series-71218?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=InsightsUK">Insights series</a>:</em></p>
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<p class="fine-print"><em><span>Scott Cairney has received funding from the Medical Research Council</span></em></p><p class="fine-print"><em><span>Aidan Horner receives funding from the Economic and Social Research Council and the Leverhulme Trust. </span></em></p>We envisage a future in which sleep is a routine target for reducing or preventing symptoms of mental illness, both in psychiatric settings and people’s homesScott Cairney, Associate Professor of Psychology, University of YorkAidan Horner, Associate Professor in Psychology and Neuroscience, University of YorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2214032024-01-31T13:36:42Z2024-01-31T13:36:42ZSleep can give athletes an edge over competitors − but few recognize how fundamental sleep is to performance<figure><img src="https://images.theconversation.com/files/571989/original/file-20240129-15-rvkoy3.jpg?ixlib=rb-1.1.0&rect=8%2C0%2C2663%2C1778&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sleep has been an underappreciated strategy for gaining an edge over an opponent at any level of athletic competition.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/ChiefsRavensFootball/47d36cdc32f2464d8b6aaed9cba32412/photo?Query=football%20playoffs&mediaType=photo,video,graphic,audio&sortBy=&dateRange=now-24h&totalCount=54&currentItemNo=44">AP Photo/Alex Brandon</a></span></figcaption></figure><p>In the adrenaline-packed world of professional sports, the power of sleep rarely gets adequate attention.</p>
<p>A healthy sleep pattern can be a stealthy game plan for athletes to gain an edge over their opponents. Only a <a href="https://www.cnbc.com/2018/12/21/lebron-james-reveals-the-nighttime-routine-that-sets-him-up-for-success.html">few top elite athletes</a> know the secret of early bedtimes for optimal performance.</p>
<p>Sleep is vital not only for keeping the mind sharp and body healthy but also for excelling in all fields in life – whether <a href="https://theconversation.com/school-start-times-and-screen-time-late-in-the-evening-exacerbate-sleep-deprivation-in-us-teenagers-179178">in the classroom</a>, on the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5158299/">battlefield</a> or in <a href="https://doi.org/10.1093/sleep/zsab051">other professional arenas</a>. </p>
<p>As a <a href="https://www.neurology.pitt.edu/people/joanna-fong-isariyawongse-md-faes-faan">neurologist specializing in sleep medicine</a> at the University of Pittsburgh, I have devoted my career to understanding and advocating for the importance of sleep health. </p>
<p>Here are some key facts to understand why sleep matters.</p>
<h2>The critical role of sleep in performance</h2>
<p>Sleep is a complex, <a href="https://www.sleepfoundation.org/stages-of-sleep#">cyclical process</a> that progresses through several stages, each with distinct characteristics and functions. Initially, it begins with light sleep, <a href="https://www.ncbi.nlm.nih.gov/books/NBK526132/#">encompassing stages 1 and 2</a>, where the body starts to relax and brain wave activity begins to slow down. </p>
<p>These stages are followed by deep sleep, also known as <a href="https://www.sleepfoundation.org/stages-of-sleep/slow-wave-sleep#:">slow-wave sleep</a>, where the body undergoes significant restorative processes. The final stage is <a href="https://my.clevelandclinic.org/health/body/12148-sleep-basics">rapid eye movement</a>, or REM sleep, characterized by vivid dreams and increased brain activity. Typically, a person cycles through these stages four to six times each night, with each cycle lasting approximately 90 minutes. </p>
<p>Sleep is when our bodies heal. Deep sleep helps repair muscles and bones through several key mechanisms, including the release of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824213/">human growth hormone</a> – a protein produced in the pituitary gland – and various <a href="https://doi.org/10.1038/npp.2016.148">anti-inflammatory agents</a>. </p>
<p><a href="https://www.health.harvard.edu/diseases-and-conditions/growth-hormone-athletic-performance-and-aging">Human growth hormone is a key player</a> in <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824213/">muscle development, tissue repair</a> and <a href="https://doi.org/10.1210/er.2008-0027">metabolism</a>, and is it vital for maintaining physical health. It significantly enhances the body’s capacity for self-repair, be it following an intense sports event or recovering from a sports-related injury. </p>
<p>In addition, sleep helps your brain to recalibrate through the waste-clearing <a href="https://doi.org/10.1016/j.sleep.2022.11.012">glymphatic system</a>, which is part of the central nervous system. Think of it as a dishwasher in your brain, flushing out waste products, including neurotoxic proteins such as <a href="https://doi.org/10.3389/fphar.2015.00221">amyloid-beta</a>, <a href="https://doi.org/10.1111%2Fj.1755-5949.2010.00177.x">abnormal tangles of a protein called tau</a> and <a href="https://doi.org/10.1101%2Fcshperspect.a009399">alpha-synuclein proteins</a>. </p>
<p>All three of those proteins have direct association with neurodegenerative diseases such as <a href="https://doi.org/10.1001/jamaneurol.2023.3889">Alzheimer’s dementia</a> and <a href="https://doi.org/10.1016/j.neubiorev.2017.08.016">chronic traumatic encephalopathy</a>, a disorder thought to be caused by repeated head injuries. For athletes, maintaining proper brain health and cognitive function is paramount.</p>
<p>In addition, deep sleep <a href="https://doi.org/10.1007/s00424-011-1044-0">strengthens the immune system</a> to help keep us healthy and free of illnesses.</p>
<p>REM sleep is the most active stage of sleep, the one in which we experience dreams. This contrasts with deep sleep, where the brain enters a state of synchronized slow waves, indicative of restorative rest. REM sleep is <a href="https://doi.org/10.1007/s11910-013-0430-8">essential for memory</a> and <a href="https://doi.org/10.3389/fpsyg.2019.00459">emotion processing</a>, which help with recall and reducing anxiety. </p>
<p>Athleticism by its purest definition and overall body control can often be linked to the benefits of Stage 2 sleep, which has been shown to play an instrumental role in the <a href="https://doi.org/10.1371/journal.pbio.1002429">consolidating of motor sequence memories</a> and physical skills learned during practice.</p>
<p>To fully benefit from these sleep cycles, adults need <a href="https://www.sciencedirect.com/science/article/abs/pii/S2352721815000157?via%3Dihub">seven to nine hours</a> of sleep per night. This duration ensures that they complete the necessary four to six sleep cycles, allowing their bodies and minds to fully experience the restorative effects of each sleep stage, which is essential for optimal health and performance.</p>
<figure>
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<figcaption><span class="caption">Sleep is a performance enhancer, if you do it right.</span></figcaption>
</figure>
<h2>How sleep helps prevent injuries</h2>
<p>In professional sports, more training and higher pressure increase the chances of getting hurt. Research shows that collegiate athletes who sleep less than seven hours per night are <a href="https://doi.org/10.1249/JSR.0000000000000849">nearly twice as likely to get injured</a> when compared with those who sleep more than eight hours. In a game like football, where split-second decisions can lead to a touchdown or interception, a well-rested brain is the best tool for quick thinking and staying free of injury. </p>
<p>Good sleep also cuts down on the <a href="https://doi.org/10.1016/j.sleep.2019.03.008">risk of concussions</a>, which, sadly, are pretty common in sports. Up to <a href="https://doi.org/10.1097/00001199-200609000-00001">3.8 million cases</a> of concussions occur annually in the U.S. during competitive sports. Studies have shown that <a href="https://doi.org/10.1016/j.sleep.2019.03.008">sleepy athletes</a> are nearly three times more likely to suffer a concussion.</p>
<p>Sleep deficits have been linked to decreased performance in every cognitive measure, including <a href="https://doi.org/10.1093/sleep/zsab051">vigilant attention, spatial cognition</a> and tasks involving <a href="https://doi.org/10.1016/j.jadohealth.2013.12.034">inhibitory control</a>. On the sports field, this translates to sleepy athletes making more impulsive and risky decisions. </p>
<h2>Enhancing athletic performance through ample sleep</h2>
<p>Athletes of any level, even at the highest levels of competition, could gain a competitive edge by giving more attention to the value of sleep. Studies focusing on <a href="https://doi.org/10.1249/MSS.0b013e31820abc5a">sprinters</a>, <a href="https://doi.org/10.1016/j.physbeh.2013.07.002">tennis players</a> and <a href="https://doi.org/10.1249/MSS.0b013e31820abc5a">endurance athletes</a> have found that sleep can enhance the following four key abilities: </p>
<ul>
<li><p><a href="https://doi.org/10.1249/MSS.0b013e31820abc5a">Speed, strength and endurance</a>: More sleep can lead to faster sprint times, greater strength and <a href="https://doi.org/10.1007/s00421-009-1103-9">higher endurance</a>, which are crucial in sports where every second counts. Adequate sleep enhances muscle recovery and energy restoration, which are crucial for the strength and power needed in sprinting. </p></li>
<li><p>Accuracy and reaction time: One study found that tennis players who got more sleep showed better <a href="https://doi.org/10.1016/j.physbeh.2013.07.002">accuracy and faster reaction times</a>. Increased sleep enhances brain function by boosting cognitive processes such as focus, <a href="https://doi.org/10.1093/sleep/zsab051">decision-making</a> and sensory perception. Well-rested individuals also experience <a href="https://doi.org/10.1371/journal.pbio.1002429">better neuromuscular coordination</a>, essential for precise movements and quick responses. </p></li>
</ul>
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<figcaption><span class="caption">Sleep can make a critical difference when it comes to split-second decision-making.</span></figcaption>
</figure>
<ul>
<li><p>Cognitive skills and inhibitory control: Good sleep helps with <a href="https://doi.org/10.1093/sleep/zsab051">strategizing and decision-making</a> through improved recall and a clearer mind, thanks to the cleansing action of the glymphatic system. Sleep deprivation, on the other hand, can impair cognitive abilities, as evidenced in <a href="https://doi.org/10.1093/sleep/zsab051">research involving NASA recruits</a>. </p></li>
<li><p>Pain tolerance: More sleep can lead to <a href="https://doi.org/10.5665/sleep.1830">increased pain tolerance</a>, playing a vital role in the quality of life and recovery process following injuries or intense physical exertion. While the exact mechanisms are complex and involve a two-way relationship between sleep and pain, this benefit is particularly important in physically demanding sports. Improved pain tolerance can aid athletes not only in recovery but also in maintaining mental well-being, allowing them to focus on rehabilitation and training without being overly hindered by discomfort. </p></li>
</ul>
<h2>Essential sleep tips for peak performance</h2>
<p>Here are some practical and effective sleep tips tailored for athletes, designed to help them harness the power of sleep for top-notch performance in their respective sports: </p>
<ul>
<li><p>Consistency and quantity: A regular sleep schedule is crucial for peak performance. Athletes should make sure they’re getting eight to 10 hours of sleep, not just the day before a big game but every day throughout the competitive season. </p></li>
<li><p>Environment: A sleep-conducive environment – dark, quiet and cool – is essential to getting a restful night’s sleep.</p></li>
<li><p>Pre-sleep routines: Relaxing activities such as reading, stretching and meditation before bed can enhance sleep quality.</p></li>
<li><p>Screen limits: <a href="https://theconversation.com/school-start-times-and-screen-time-late-in-the-evening-exacerbate-sleep-deprivation-in-us-teenagers-179178">Reducing screen time</a> before bed helps maintain natural sleep rhythms and the production of melatonin.</p></li>
<li><p><a href="https://theconversation.com/whats-the-best-diet-for-healthy-sleep-a-nutritional-epidemiologist-explains-what-food-choices-will-help-you-get-more-restful-zs-219955">Dietary considerations</a>: Avoiding caffeine, alcohol and heavy meals before sleep aids in restfulness.</p></li>
<li><p><a href="https://theconversation.com/short-naps-can-improve-memory-increase-productivity-reduce-stress-and-promote-a-healthier-heart-210449">Strategic napping</a>: Short, well-timed naps can be a valuable tool for recovery and achieving peak performance. </p></li>
<li><p>Sleep banking: To prepare for travel when you anticipate reduced sleep, consider sleeping longer beforehand. This can be achieved either through extra napping or by extending your regular nightly sleep. </p></li>
</ul>
<p>It’s important for any athlete to remember that sleep isn’t a weakness. Success as an athlete is about more than just physical training and tactical preparedness; it’s also about harnessing the power of sleep for optimal performance.</p><img src="https://counter.theconversation.com/content/221403/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joanna Fong-Isariyawongse does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Studies show college athletes sleeping less than 7 hours per night are almost twice as likely to be injured when compared with athletes sleeping more than 8 hours.Joanna Fong-Isariyawongse, Associate Professor of Neurology, University of PittsburghLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2204922024-01-03T16:12:29Z2024-01-03T16:12:29ZThe study of dreams: Scientists uncover new communication channels with dreamers<figure><img src="https://images.theconversation.com/files/567657/original/file-20231115-19-szdbgp.jpg?ixlib=rb-1.1.0&rect=8%2C0%2C5982%2C3889&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In 1981, Keith Hearne and Stephen Laberge asked dreamers to send "telegrams" to the outside world. More than 30 years later, scientists continue to blaze trails to communicate with the sleeping mind. </span> <span class="attribution"><a class="source" href="https://unsplash.com/fr/photos/fond-decran-numerique-de-bateau-a-voile-noir-DKix6Un55mw">Johannes Plenio/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>In his sci-fi film <a href="https://www.youtube.com/watch?v=YoHD9XEInc0"><em>Inception</em></a> (2010), Christophe Nolan imagined his protagonist slipping into other people’s dreams and even shaping their contents. But what if this story wasn’t so far away from real life?</p>
<p>Our research suggests that it is possible to interact with volunteers while they are asleep, and even to converse with them at certain key moments.</p>
<h2>The scientific study of dreams</h2>
<p>While we sometimes wake up with vivid memories from our nocturnal adventures, at others the impression of a dreamless night prevails.</p>
<p>Research shows we remember on average <a href="https://www.frontiersin.org/articles/10.3389/fneur.2012.00106/full">one to three dreams per week</a>. However, not everyone is equal when it comes to recalling dreams. People who say they never dream make up around <a href="https://www.sciencedirect.com/science/article/abs/pii/S1389945702002551">2.7 to 6.5% of the population</a>. Often, these people used to recall their dreams when they were children. The proportion of people who say they have never dreamt in their entire life is very low: 0.38%.</p>
<p>Whether people remember their dreams depends on <a href="https://www.frontiersin.org/articles/10.3389/fneur.2020.00724/full">many factors</a> such as gender (women remember their dreams more frequently than men), one’s interest in dreams, as well as the <a href="https://www.researchgate.net/publication/326900077_Researching_Dreams_The_Fundamentals">way dreams are collected</a> (some might find it handy to keep track of them with a “dream journal” or a recorder, for example).</p>
<p>The private and fleeting nature of dreams makes it tricky for scientists to capture them. Nowadays, however, thanks to knowledge acquired in the field of neuroscience, it is possible to classify a person’s state of alertness by analysing their brain activity, muscle tone and eye movements. Scientists can thus determine whether a person is asleep, and what stage of sleep they are in: sleep onset, light slow wave sleep, deep slow wave sleep or rapid eye movement (REM) sleep.</p>
<p>What this physiological data does not do is tell us whether a sleeper is dreaming (dreams can occur in all stages of sleep), let alone what they’re dreaming about. Researchers don’t have access to the dream experience as it happens. They are therefore forced to rely on the dreamer’s account upon waking, with no guarantee that this account is faithful to what happened in the sleeper’s head.</p>
<figure class="align-center ">
<img alt="Photo of a woman sleeping in a caravan, from behind." src="https://images.theconversation.com/files/559967/original/file-20231116-25-axyh3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559967/original/file-20231116-25-axyh3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559967/original/file-20231116-25-axyh3v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559967/original/file-20231116-25-axyh3v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559967/original/file-20231116-25-axyh3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559967/original/file-20231116-25-axyh3v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559967/original/file-20231116-25-axyh3v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">What one dreams about remains a well-kept secret.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/fr/photos/donna-che-dorme-sulla-roulotte-ffustAcaX0E">Михаил Калегин/Unsplash</a></span>
</figcaption>
</figure>
<p>Moreover, to understand what happens in the brain while dreaming – and what purpose this activity serves – we would need to be able to compare brain activity during times when dreams occur with those when they are absent. It is therefore imperative to determine precisely when dreams occur in order to further the science of dreams.</p>
<p>To achieve this, it would be ideal to be able to communicate with sleepers. Impossible? Not for everyone - that’s where lucid dreamers come in.</p>
<h2>Lucid dreaming</h2>
<p>Most of us only realise we’ve been dreaming upon waking. Lucid dreamers, on the other hand, have the unique ability to remain aware of the dreaming process during REM sleep, a stage of sleep during which brain activity is closer to that of the waking phase.</p>
<p>Even more surprisingly, lucid dreamers can sometimes exercise partial control over their dream’s narrative. They are then able to fly away, make people appear or disappear, change the weather or transform themselves into animals. In short, the possibilities are endless.</p>
<p>Such lucid dreams can occur spontaneously or be engineered by specific training. The existence of lucid dreaming has been known since ancient times, but for a long time it was considered esoteric and unworthy of scientific exploration.</p>
<p>Such views have changed thanks to a <a href="https://journals.sagepub.com/doi/abs/10.2466/pms.1981.52.3.727">clever experiment</a> set up by psychologist Keith Hearne and psychophysiologist Stephen Laberge in the 1980s. These two researchers set out to prove that lucid dreamers were indeed asleep when they realised they were dreaming. Departing from the observation that REM sleep is characterised by rapid eye movements while one’s eyes are shut (hence the name ‘Rapid Eye Movement sleep’), they asked themselves the following question: would it be possible to use this property to ask the sleeper to send a “telegram” from their dream to the world around them?</p>
<p>Hearne and Laberge recruited lucid dreamers to try to find out. They agreed with them before they fell asleep on the telegram to be sent: the participants would have to make specific eye movements, such as moving their gaze from left to right three times, as soon as they became aware that they were dreaming. And while they were objectively in REM sleep, the lucid dreamers did just that.</p>
<p>The new communication code allowed researchers from then on to detect dreaming stages in real time. The work paved the way for many research projects in which lucid dreamers act as undercover agents in the dream world, carrying out missions (such as <a href="https://www.nature.com/articles/s41598-018-21067-9">holding one’s breath</a> in a dream) and signalling them to the experimenters using the eye code.</p>
<p>It is now possible to combine such experiments with brain imaging techniques to study the brain regions involved in lucid dreaming. This represents a huge step forward in the quest for a better understanding of dreams and how they are formed.</p>
<p>In 2021, almost 40 years after the pioneering work of Hearne and Laberge, our <a href="https://www.cell.com/current-biology/pdfExtended/S0960-9822(21)00059-2">study</a> in collaboration with academics from around the world has taken us even further.</p>
<h2>From fiction to reality: talking to the dreamer</h2>
<p>We already knew that lucid dreamers were capable of sending information from their dreams. But can they also receive it? In other words, is it possible to talk to a lucid dreamer? To find out, we exposed a lucid dreamer to tactile stimuli while he was asleep. We also asked him closed questions such as “Do you like chocolate?”. </p>
<p>He was able to respond by smiling to indicate “Yes” and by frowning to indicate “No”. Lucid dreamers were also presented with simple mathematical equations verbally. They were able to provide appropriate answers while remaining asleep.</p>
<p>Of course, lucid dreamers didn’t always respond, far from it. But the fact that they sometimes did (18% of cases in our study) opened a communication channel between experimenters and dreamers.</p>
<p>However, lucid dreaming remains a rare phenomenon and even lucid dreamers are not lucid all the time or throughout REM sleep. Was the communication portal we had opened limited to “lucid” REM sleep alone? To find out, we undertook further work.</p>
<h2>Expanding the communication portal</h2>
<p>To find out whether we could communicate in the same way with any sleeper, whatever their stage of sleep, we conducted experiments with non-lucid dreaming volunteers without sleeping disorders, as well as with people suffering from narcolepsy. This disease, which causes involuntary sleep, sleep paralysis and an early onset of the REM phase, is associated with an <a href="https://academic.oup.com/sleep/article/38/3/487/2416990">increased propensity</a> for lucid dreaming.</p>
<p>In <a href="https://www.nature.com/articles/s41593-023-01449-7">our latest experiment</a>, we presented participants with existing words (e.g. “pizza”) and others that we made up (e.g. “ditza”) across all sleep stages. We asked them to smile or frown to signal whether the word had been made up or not. Unsurprisingly, people with narcolepsy were able to respond when they were lucid in REM sleep, confirming our results from 2021.</p>
<p>More surprisingly, both groups of participants were also able to respond to our verbal stimuli in most stages of sleep, even in the absence of lucid dreaming. The volunteers were able to respond intermittently, as if windows of connection with the outside world were opening temporarily at certain precise moments.</p>
<p>We were even able to determine the composition of brain activity conducive to these moments of openness to the outside world. By analysing it before the stimuli were presented, we were able to predict whether the sleepers would respond or not.</p>
<p>Why do such windows of connection with the outside world exist? We can put forward the hypothesis that the brain developed in a context where a minimum of cognitive processing was necessary during sleep. We can imagine, for example, that our ancestors had to remain attentive to external stimuli while they were asleep, in case a predator approached. Similarly, we know that a mother’s brain reacts preferentially to her baby’s cries during sleep.</p>
<p>Our results suggest that it is now possible to “talk” to any sleeper, whatever stage of sleep they are in. By refining the brain markers that predict the moments of connection with the outside world, it should be possible to further optimise communication protocols in the future.</p>
<p>This breakthrough paves the way for real-time dialogue with sleepers, offering researchers the chance to explore the mysteries of dreams as they happen. But if the line between science fiction and reality is getting thinner, rest assured: neuroscientists are still a long way from being able to decipher your wildest fantasies.</p><img src="https://counter.theconversation.com/content/220492/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Les auteurs ne travaillent pas, ne conseillent pas, ne possèdent pas de parts, ne reçoivent pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'ont déclaré aucune autre affiliation que leur organisme de recherche.</span></em></p>Some dreamers were able to distinguish real words from invented ones by smiling or frowning.Başak Türker, Chercheuse postdoctorale, Institut du Cerveau (ICM)Delphine Oudiette, Chercheure en neurosciences cognitives, InsermLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2074062023-09-26T02:03:09Z2023-09-26T02:03:09ZWhat do people think about when they go to sleep?<figure><img src="https://images.theconversation.com/files/547143/original/file-20230908-27-efu6e7.jpg?ixlib=rb-1.1.0&rect=0%2C6%2C4585%2C3052&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>You’re lying in bed, trying to fall asleep but the racing thoughts won’t stop. Instead, your brain is busy making detailed plans for the next day, replaying embarrassing <a href="https://www.tiktok.com/@ryanhdlombard/video/7052464974324583681?q=sleep%20thoughts&t=1693536926124">moments</a> (“why did I say that?”), or producing seemingly random thoughts (“where is my birth certificate?”). </p>
<p>Many social media users have shared <a href="https://www.tiktok.com/@komasawn/video/7267320333613419818">videos</a> on how to fall asleep faster by <a href="https://www.tiktok.com/@lilslvrtt/video/7225272823562997000">conjuring</a> up “<a href="https://www.tiktok.com/@ekai.is.okay/video/7169530076143439131?q=fake%20scenario%20fall%20asleep&t=1693537172625">fake scenarios</a>”, such as a romance storyline where you’re the main character.</p>
<p>But what does the research say? Does what we think about before bed influence how we sleep?</p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/CpIsv-ftXLD/?img_index=5","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
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Read more:
<a href="https://theconversation.com/how-do-i-stop-my-mind-racing-and-get-some-sleep-207904">How do I stop my mind racing and get some sleep?</a>
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<h2>How you think in bed affects how you sleep</h2>
<p>It turns out people who sleep well and those who sleep poorly have different kinds of thoughts before bed.</p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S1087079219302217">Good sleepers report</a> experiencing mostly visual sensory images as they drift to sleep – seeing people and objects, and having dream-like experiences.</p>
<p>They may have less ordered thoughts and more hallucinatory experiences, such as imagining you’re participating in events in the real world.</p>
<p>For people with insomnia, pre-sleep thoughts tend to be less visual and more focused on planning and problem-solving. These thoughts are also generally more unpleasant and less random than those of good sleepers.</p>
<p>People with insomnia are also more likely to stress about sleep as they’re <em>trying</em> to sleep, leading to a vicious cycle; putting effort into sleep actually wakes you up more.</p>
<p>People with insomnia often <a href="https://bpspsychub.onlinelibrary.wiley.com/doi/abs/10.1348/014466500163284">report</a> worrying, planning, or thinking about important things at bedtime, or focusing on problems or noises in the environment and having a general preoccupation with not sleeping. </p>
<p>Unfortunately, all this pre-sleep mental activity can prevent you drifting off.</p>
<p>One <a href="https://academic.oup.com/sleep/article/27/1/69/2707948">study</a> found even people who are normally good sleepers can have sleep problems if they’re stressed about something at bedtime (such as the prospect of having to give a speech when they wake up). Even <a href="https://pubmed.ncbi.nlm.nih.gov/17884278/">moderate levels of stress at bedtime</a> could affect sleep that night. </p>
<p>Another <a href="https://jcsm.aasm.org/doi/full/10.5664/jcsm.6704">study</a> of 400 young adults looked at how binge viewing might affect sleep. The researchers found higher levels of binge viewing were associated with poorer sleep quality, more fatigue, and increased insomnia symptoms. “Cognitive arousal”, or mental activation, caused by an interesting narrative and identifying with characters, could play a role.</p>
<p>The good news is there are techniques you can use to change the style and content of your pre-sleep thoughts. They could help reduce nighttime cognitive arousal or to replace unwanted thoughts with more pleasant ones. These techniques are called “cognitive refocusing”.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/547144/original/file-20230908-21-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A woman lies in bed trying to sleep." src="https://images.theconversation.com/files/547144/original/file-20230908-21-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547144/original/file-20230908-21-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547144/original/file-20230908-21-efu6e7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547144/original/file-20230908-21-efu6e7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547144/original/file-20230908-21-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547144/original/file-20230908-21-efu6e7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547144/original/file-20230908-21-efu6e7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">For people with insomnia, pre-sleep thoughts tend to be less visual and more focused on planning.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What is cognitive refocusing?</h2>
<p>Cognitive refocusing, developed by US psychology researcher <a href="https://artsandsciences.syracuse.edu/people/faculty/gellis-phd-les-a/">Les Gellis</a>, involves distracting yourself with pleasant thoughts before bed. It’s like the “fake scenarios” social media users post about – but the trick is to think of a scenario that’s not <em>too</em> interesting.</p>
<p>Decide <em>before</em> you go to bed what you’ll focus on as you lie there waiting for sleep to come.</p>
<p>Pick an engaging cognitive task with enough scope and breadth to maintain your interest and attention – without causing emotional or physical arousal. So, nothing too scary, thrilling or stressful.</p>
<p>For example, if you like interior decorating, you might imagine redesigning a room in your house.</p>
<p>If you’re a football fan, you might mentally replay a passage of play or imagine a game plan. </p>
<p>A music fan might mentally recite lyrics from their favourite album. A knitter might imagine knitting a blanket.</p>
<p>Whatever you choose, make sure it’s suited to you and your interests. The task needs to feel pleasant, without being overstimulating.</p>
<p>Cognitive refocusing is not a silver bullet, but it can help.</p>
<p>One <a href="https://doi.org/10.1080/07448481.2022.2109031">study</a> of people with insomnia found those who tried cognitive refocusing had significant improvements in insomnia symptoms compared to a control group.</p>
<h2>How ancient wisdom can help us sleep</h2>
<p>Another age-old technique is mindfulness meditation. </p>
<p>Meditation practice can increase our self-awareness and make us more aware of our thoughts. This can be useful for helping with rumination; often when we try to block or stop thoughts, it can make matters worse.</p>
<p>Mindfulness training can help us recognise when we’re getting into a rumination spiral and allow us to sit back, almost like a passive observer.</p>
<p>Try just watching the thoughts, without judgement. You might even like to say “hello” to your thoughts and just let them come and go. Allow them to be there and see them for what they are: just thoughts, nothing more.</p>
<p><a href="https://doi.org/10.1007/s12671-021-01714-5">Research from our group</a> has shown mindfulness-based therapies can help people with insomnia. It may also help people with <a href="https://doi.org/10.1007/s11920-022-01370-z">psychiatric conditions</a> such as bipolar disorder, obsessive-compulsive disorder and schizophrenia get more sleep.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/547147/original/file-20230908-29-jalfwt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A woman lies in bed with an eye mask on." src="https://images.theconversation.com/files/547147/original/file-20230908-29-jalfwt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547147/original/file-20230908-29-jalfwt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547147/original/file-20230908-29-jalfwt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547147/original/file-20230908-29-jalfwt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547147/original/file-20230908-29-jalfwt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547147/original/file-20230908-29-jalfwt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547147/original/file-20230908-29-jalfwt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Try just watching your thoughts, without judgement, as you lie in bed.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What can help ease your pre-sleep thoughts?</h2>
<p>Good sleep starts the moment you wake up. To give yourself your best shot at a good night’s sleep, start by getting up at the same time each day and getting some morning light exposure (regardless of how much sleep you had the night before).</p>
<p>Have a consistent bedtime, reduce technology use in the evening, and do regular exercise during the day.</p>
<p>If your mind is busy at bedtime, try cognitive refocusing. Pick a “fake scenario” that will hold your attention but not be too scary or exciting. Rehearse this scenario in your mind at bedtime and enjoy the experience.</p>
<p>You might also like to try: </p>
<ul>
<li><p>keeping a consistent bedtime routine, so your brain can wind down</p></li>
<li><p>writing down worries earlier in the day (so you don’t think about them at bedtime)</p></li>
<li><p>adopting a more self-compassionate mindset (don’t beat yourself up at bedtime over your imagined shortcomings!).</p></li>
</ul>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-do-we-wake-around-3am-and-dwell-on-our-fears-and-shortcomings-169635">Why do we wake around 3am and dwell on our fears and shortcomings?</a>
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<img src="https://counter.theconversation.com/content/207406/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Melinda Jackson receives funding from NHMRC, Brain Foundation and Dementia Australia. </span></em></p><p class="fine-print"><em><span>Hailey Meaklim is the founder of My Better Sleep. </span></em></p>It turns out people who sleep well and those who sleep poorly have different kinds of thoughts before bed.Melinda Jackson, Associate Professor at Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash UniversityHailey Meaklim, Sleep Psychologist and Researcher, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2109012023-09-08T01:11:58Z2023-09-08T01:11:58ZThe science of dreams and nightmares – what is going on in our brains while we’re sleeping?<figure><img src="https://images.theconversation.com/files/545455/original/file-20230830-27-ozyppi.jpg?ixlib=rb-1.1.0&rect=35%2C0%2C5946%2C3979&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.pexels.com/photo/photo-of-a-woman-sleeping-near-fluffy-clouds-8264248/">Pexel/Ron Lach</a></span></figcaption></figure><p>Last night you probably slept for <a href="https://www.sciencedirect.com/science/article/pii/S2352721816301292">seven to eight hours</a>. About one or two of these was likely in deep sleep, especially if you’re young or physically active. That’s because <a href="http://apsychoserver.psych.arizona.edu/jjbareprints/psyc501a/readings/Carskadon%20Dement%202011.pdf">sleep changes with age</a> and <a href="https://www.hindawi.com/journals/apm/2017/1364387/">exercise</a> affects brain activity. About three or four hours will have been spent in light sleep. </p>
<p>For the remaining time, you were likely in rapid eye movement (REM) sleep. While this is not the only time your brain is potentially dreaming – we also dream during other sleep stages – it is the time your brain activity is most likely to be recalled and reported when you’re awake. </p>
<p>That’s usually because either really weird thoughts or feelings wake you up or because the last hour of sleep is nearly all <a href="https://www.researchgate.net/profile/Elizaveta-Solomonova/publication/320356182_Dream_Recall_and_Content_in_Different_Stages_of_Sleep_and_Time-of-Night_Effect/links/5a707bdb0f7e9ba2e1cade56/Dream-Recall-and-Content-in-Different-Stages-of-Sleep-and-Time-of-Night-Effect.pdf">REM sleep</a>. When dreams or your alarm wake you, you’re likely coming out of dream sleep and your dream often lingers into the first few minutes of being awake. In this case you remember it.</p>
<p>If they’re strange or interesting dreams, you might tell someone else about them, which may further <a href="https://link.springer.com/article/10.1007/s00426-022-01722-7">encode</a> the dream memory.</p>
<p>Dreams and nightmares are mysterious and we’re still learning about them. They keep our brains ticking over. They wash the thoughts from the day’s events at a molecular level. They might even help us imagine what’s possible during our waking hours. </p>
<h2>What do scientists know about REM sleep and dreaming?</h2>
<p>It’s really hard to study dreaming because people are asleep and we can’t observe what’s going on. Brain imaging has indicated certain <a href="https://www.sciencedirect.com/science/article/pii/S1087079216300673#sec3">patterns of brain activity</a> are associated with dreaming (and with certain sleep stages where dreams are more likely to occur). But such studies ultimately rely on self-reports of the dream experience. </p>
<p>Anything we spend so much time doing probably serves multiple ends. </p>
<p>At the basic physiological level (indicated by <a href="https://www.sciencedirect.com/science/article/pii/S1053810021001409">brain activity, sleep behaviour and studies of conciousness</a>), all mammals dream – even the platypus and echidna probably experience something similar to dreaming (provided they are at the <a href="https://www.wired.com/2014/07/the-creature-feature-10-fun-facts-about-the-echidna/#:%7E:text=It%20was%20long%20thought%20that,re%20at%20the%20right%20temperature.">right temperature</a>). Their brain activity and sleep stages align to some degree with human <a href="https://www.sciencedirect.com/science/article/pii/S1053810021001409#b0630">REM sleep</a>. </p>
<p>Less evolved species do not. Some <a href="https://www.sciencedirect.com/science/article/pii/S2468867319301993#sec0030">jellyfish</a> – who do not have a brain – do experience what could physiologically be characterised as sleep (shown by their posture, quietness, lack of responsiveness and rapid “waking” when prompted). But they do not experience the same physiological and behavioural elements that resemble REM dream sleep. </p>
<p>In humans, REM sleep is thought to occur cyclically every 90 to 120 minutes across the night. It prevents us from sleeping too deeply and being <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4972941/">vulnerable to attack</a>. Some scientists think we dream in order to stop our brains and bodies from getting too cold. Our core body temperature is typically <a href="https://www.thelancet.com/journals/laneur/article/PIIS1474-4422(22)00210-1/fulltext">higher while dreaming</a>. It is typically easier to <a href="https://www.tandfonline.com/doi/pdf/10.2147/NSS.S188911">wake from dreaming</a> if we need to respond to external cues or dangers. </p>
<p>The brain activity in REM sleep kicks our brain into gear for a bit. It’s like a periscope into a more conscious state, observing what’s going on at the surface, then going back down if all is well. </p>
<p>Some evidence suggests “fever dreams” are far less common than we might expect. We actually experience <a href="https://www.frontiersin.org/articles/10.3389/fpsyg.2020.00053/full">far less REM sleep</a> when we have a fever – though the dreams we do have tend to be <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3830719/">darker in tone and more unusual</a>. </p>
<p>Spending less time in REM sleep when we’re feverish might happen because we are far less capable of regulating our body temperature in this stage of sleep. To protect us, our brain tries to regulate our temperature by “skipping” this sleep stage. We tend to have fewer dreams when the weather is hot <a href="https://www.tandfonline.com/doi/abs/10.1080/23744731.2020.1756664">for the same reason</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/545459/original/file-20230830-17-n6ash3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="bed in pink landscape" src="https://images.theconversation.com/files/545459/original/file-20230830-17-n6ash3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/545459/original/file-20230830-17-n6ash3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545459/original/file-20230830-17-n6ash3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545459/original/file-20230830-17-n6ash3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545459/original/file-20230830-17-n6ash3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545459/original/file-20230830-17-n6ash3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545459/original/file-20230830-17-n6ash3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dreams are when our brain washes itself clean.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/bed-on-colorful-flowers-on-cape-10079452/">Pexels/Mo Eid</a></span>
</figcaption>
</figure>
<h2>A deep-cleaning system for the brain</h2>
<p>REM sleep is important for ensuring our brain is working as it should, as indicated by studies using <a href="https://www.cell.com/current-biology/pdf/S0960-9822(17)31329-5.pdf">electoencephalography</a>, which measures brain activity. </p>
<p>In the same way deep sleep helps the body restore its physical capacity, dream sleep “<a href="https://www.cell.com/current-biology/pdf/S0960-9822(17)31329-5.pdf">back-flushes</a>” our neural circuits. At the molecular level, the chemicals that underpin our thinking are bent out of shape by the day’s cognitive activity. Deep sleep is when those chemicals are returned to their unused shape. The brain is “<a href="https://www.science.org/doi/abs/10.1126/science.1241224">washed</a>” with cerebrospinal fluid, controlled by the <a href="https://theconversation.com/on-your-back-side-face-down-mice-show-how-we-sleep-may-trigger-or-protect-our-brain-from-diseases-like-als-181954">glymphatic system</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/on-your-back-side-face-down-mice-show-how-we-sleep-may-trigger-or-protect-our-brain-from-diseases-like-als-181954">On your back? Side? Face-down? Mice show how we sleep may trigger or protect our brain from diseases like ALS</a>
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<p>At the next level, dream sleep “tidies up” our recent memories and feelings. During <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC534695/">REM sleep</a>, our brains consolidate procedural memories (of how to do tasks) and emotions. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC534695/">Non-REM sleep</a>, where we typically expect fewer dreams, is important for the consolidation of episodic memories (events from your life). </p>
<p>As our night’s sleep progresses, we produce more cortisol - the <a href="https://psycnet.apa.org/record/2005-01907-021">stress hormone</a>. It is thought the amount of cortisol present can impact the type of memories we are consolidating and potentially the types of dreams we have. This means the dreams we have later in the night may be <a href="https://learnmem.cshlp.org/content/11/6/671.full.pdf">more fragmented or bizarre</a>. </p>
<p>Both kinds of sleep help <a href="https://www.researchgate.net/profile/Jb-Eichenlaub/publication/313545620_Daily_Life_Experiences_in_Dreams_and_Sleep-Dependent_Memory_Consolidation/links/5c532b0ba6fdccd6b5d76270/Daily-Life-Experiences-in-Dreams-and-Sleep-Dependent-Memory-Consolidation.pdf?ref=nepopularna.org">consolidate</a> the useful brain activity of the day. The brain also discards less important information. </p>
<h2>Random thoughts, rearranged feelings</h2>
<p>This filing and discarding of the day’s activities is going on while we are sleeping. That’s why we often dream about things that happen <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0264574">during the day</a>. </p>
<p>Sometimes when we’re rearranging the thoughts and feelings to go in the “<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3921176/">bin</a>” during sleep, our level of consciousness allows us to experience awareness. Random thoughts and feelings end up all jumbled together in weird and wonderful ways. Our awareness of this process may explain the bizarre nature of some of our dreams. Our daytime experiences can also fuel nightmares or anxiety-filled dreams after a <a href="https://www.sleepfoundation.org/dreams/how-trauma-can-affect-dreams">traumatic event</a>.</p>
<p>Some dreams appear to <a href="https://rai.onlinelibrary.wiley.com/doi/pdfdirect/10.1111/j.1467-9655.2010.01668.x">foretell the future or carry potent symbolism</a>. In many societies dreams are believed to be a window into an <a href="https://digitalcommons.ciis.edu/cgi/viewcontent.cgi?article=1050&context=ijts-transpersonalstudies">alternate reality</a> where we can envisage what is possible.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/545460/original/file-20230830-29-3jrotm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/545460/original/file-20230830-29-3jrotm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/545460/original/file-20230830-29-3jrotm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=355&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545460/original/file-20230830-29-3jrotm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=355&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545460/original/file-20230830-29-3jrotm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=355&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545460/original/file-20230830-29-3jrotm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=447&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545460/original/file-20230830-29-3jrotm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=447&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545460/original/file-20230830-29-3jrotm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=447&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Memories can be cemented by and fuel dreams and nightmares.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/assorted-photos-on-table-1989747/">Pexels/Suzy Hazelwood</a></span>
</figcaption>
</figure>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sleeping-on-it-helps-you-better-manage-your-emotions-and-mental-health-heres-why-179156">‘Sleeping on it’ helps you better manage your emotions and mental health – here’s why</a>
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<h2>What does it all mean?</h2>
<p>Our scientific understanding of the thermoregulatory, molecular and basic neural aspects of dreaming sleep is <a href="https://www.nature.com/articles/nrn2716">good</a>. But the psychological and spiritual aspects of dreaming remain largely hidden. </p>
<p>Perhaps our brains are wired to try and make sense of things. Human societies have always interpreted the random – birds wheeling, tea leaves and the planets – and looked for <a href="https://brill.com/display/book/edcoll/9789047407966/B9789047407966-s003.xml">meaning</a>. Nearly every human society has regarded dreams as more than just random neural firing. </p>
<p>And the history of science tells us some things once thought to be magic can later be understood and harnessed – for better or worse.</p><img src="https://counter.theconversation.com/content/210901/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Dreams keep our brains ticking over. They wash the thoughts from the day’s events at a molecular level. They might even help us imagine what’s possible during our waking hours.Drew Dawson, Director, Appleton Institute, CQUniversity AustraliaMadeline Sprajcer, Lecturer in Psychology, CQUniversity AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2015272023-05-26T12:26:57Z2023-05-26T12:26:57ZA little-understood sleep disorder affects millions and has clear links to dementia – 4 questions answered<figure><img src="https://images.theconversation.com/files/527576/original/file-20230522-6205-s3h5qy.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C5103%2C3410&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Past age 50, men are much more likely to have REM sleep behavior disorder than women.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/caucasian-man-sleeping-royalty-free-image/92305206?phrase=50+year+old+sleeping&adppopup=true">Jose Luis Pelaez/Stone via Getty Images</a></span></figcaption></figure><p><em>A little-known and poorly understood sleep disorder that occurs during the rapid eye movement, or REM, <a href="https://www.cancer.gov/publications/dictionaries/cancer-terms/def/rem-sleep">stage of sleep</a> <a href="https://www.scientificamerican.com/article/acting-out-dreams-predicts-parkinsons-and-other-brain-diseases/">has been garnering attention</a> for its role in foreshadowing neurodegenerative brain diseases such as <a href="https://www.nia.nih.gov/health/parkinsons-disease#">Parkinson’s disease</a> and <a href="https://www.alz.org/alzheimers-dementia/what-is-dementia/types-of-dementia/dementia-with-lewy-bodies">dementia with Lewy bodies</a>. The disorder, known as <a href="https://my.clevelandclinic.org/health/diseases/24465-rem-sleep-behavior-disorder-rbd#">REM sleep behavior disorder</a>, or RBD in the medical field, affects around 1% of the general population worldwide and <a href="https://www.uptodate.com/contents/rapid-eye-movement-sleep-behavior-disorder/print">about 2% of adults over 65</a>.</em> </p>
<p><em>The Conversation talked with <a href="https://uvahealth.com/findadoctor/Anelyssa-D%27Abreu-1891243507">Anelyssa D'Abreu</a>, a neurologist who specializes in geriatric neurology, to explain what researchers know about the condition’s links to dementia.</em></p>
<h2>1. What is REM sleep behavior disorder?</h2>
<p>Every night, you go through four to five sleep cycles. Each cycle, lasting about 90 to 110 minutes, has four stages. That fourth stage is REM sleep. </p>
<p>REM sleep only comprises <a href="https://www.ncbi.nlm.nih.gov/books/NBK526132/#">20% to 25% of total sleep</a>, but its proportion increases throughout the night. During REM sleep, your brain rhythms are similar to when you are awake, your muscles lose tone so you are unable to move, and your eyes, while closed, move quickly. This stage is often accompanied by muscle twitches and fluctuations in your respiratory rate and blood pressure.</p>
<p>But someone with REM sleep behavior disorder will act out their dreams. For reasons that are poorly understood, the dream content is usually violent – patients report being chased, or defending themselves, and as they sleep they shout, moan, scream, kick, punch and thrash about. </p>
<p>Injuries often result from these incidents; patients may fall from bed or accidentally harm a partner. Some 60% of patients and 20% of bed partners of people with this disorder <a href="https://www.uptodate.com/contents/rapid-eye-movement-sleep-behavior-disorder/print">sustain an injury</a> during sleep. </p>
<p>Appropriate testing, including <a href="https://sleepeducation.org/patients/sleep-study/">a sleep study</a>, are needed to determine if a patient has REM sleep behavior disorder, as opposed to another disorder, such as <a href="https://www.ncbi.nlm.nih.gov/books/NBK459252/#">obstructive sleep apnea</a>. This is a disorder in which breathing is interrupted during sleep. </p>
<p>REM sleep behavior disorder can occur at any age, but symptoms usually start with people in their 40s and 50s. For those younger than 40, antidepressants are the most common cause of REM sleep behavior disorder; in these younger patients, it affects biological males and females about equally, but past age 50, it’s more common in biological males.</p>
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<figcaption><span class="caption">If you suspect you have REM sleep behavior disorder, see a sleep specialist or neurologist.</span></figcaption>
</figure>
<h2>2. What causes REM sleep behavior disorder?</h2>
<p>The disease mechanism is not well understood. In some cases of REM sleep behavior disorder, a clear cause cannot be identified. In other cases, the disorder may be caused by something specific, such as <a href="https://www.ncbi.nlm.nih.gov/books/NBK459252/#">obstructive sleep apnea</a>, <a href="https://www.mayoclinic.org/diseases-conditions/narcolepsy/symptoms-causes/syc-20375497#">narcolepsy</a>, psychiatric disorders, use of antidepressants, autoimmune disorders and brain lesions, which are areas of damaged brain tissue.</p>
<p>In both situations, REM sleep behavior disorder <a href="https://molecularneurodegeneration.biomedcentral.com/articles/10.1186/s13024-021-00501-z#">may be associated with synucleinopathies</a>, a group of neurodegenerative disorders in which aggregates of the protein α-synuclein accumulate in brain cells. The most common of these neurodegenerative disorders is Parkinson’s disease. Others are <a href="https://www.alz.org/alzheimers-dementia/what-is-dementia/types-of-dementia/dementia-with-lewy-bodies">dementia with Lewy bodies</a>, <a href="https://www.ninds.nih.gov/health-information/disorders/multiple-system-atrophy">multiple system atrophy</a> and <a href="https://doi.org/10.1016%2Fj.mayocp.2019.03.009">pure autonomic failure</a>. REM sleep behavior disorder may precede these diseases or occur at any time during the disease process. </p>
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<figcaption><span class="caption">People with REM sleep behavior disorder can injure themselves – and their bed partners.</span></figcaption>
</figure>
<h2>3. What are the links between the sleep disorder and dementia?</h2>
<p>REM sleep behavior disorder may be <a href="https://doi.org/10.1016/j.nbd.2020.104996">the first symptom of Parkinson’s disease or dementia with Lewy bodies</a>. It is observed in 25% to 58% of patients diagnosed with Parkinson’s, 70% to 80% of patients with dementia with Lewy bodies and 90% to 100% of those with <a href="https://www.nhs.uk/conditions/multiple-system-atrophy/#">multiple system atrophy</a>.</p>
<p>In a long-term study of 1,280 patients with REM sleep behavior disorder who didn’t have <a href="https://my.clevelandclinic.org/health/diseases/22815-parkinsonism#">parkinsonism</a> – an umbrella term that refers to brain conditions, including Parkinson’s disease, that cause slowed movements, stiffness and tremors – or dementia, researchers followed participants to find out how many would develop these disorders. After 12 years, 73.5% of those with REM sleep behavior disorder had developed a <a href="https://doi.org/10.1093/brain/awz030">related neurodegenerative disorder</a>.</p>
<p>Some of the factors that independently increased the risk of developing a neurodegenerative disorder were the presence of irregular motor symptoms, abnormal dopamine levels, loss of sense of smell, cognitive impairment, abnormal color vision, erectile dysfunction, constipation and older age.</p>
<p>REM sleep behavior disorder may also be observed in other neurodegenerative disorders such as Alzheimer’s disease and Huntington’s disease, but at much lower rates. The association is also not as strong as that observed in the synucleinopathies.</p>
<h2>4. Does an early diagnosis help?</h2>
<p>For most neurodegenerative disorders, there is a phase that may last for decades in which brain changes are taking place but the patient either remains asymptomatic or develops symptoms without the full expression of the disease. RBD, in that scenario, is an early sign of those disorders. This provides an opportunity to study how the disease progresses in the brain and to develop therapies that could either slow this process or prevent it from happening. </p>
<p>At this time, there are no approved therapies to prevent the onset of these neurodegenerative diseases in those with REM sleep behavior disorder. There are, however, medications such as melatonin and clonazepam that may improve the symptoms. We also recommend measures to avoid injury, such as removing breakable objects from the room, protecting windows and padding floors. </p>
<p>Patients who are affected by REM sleep behavior disorder may choose to participate in research. Proper treatment of the disease can help prevent injury and improve quality of life.</p><img src="https://counter.theconversation.com/content/201527/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anelyssa D'Abreu receives funding from ARDRAF </span></em></p>REM sleep behavior disorder is characterized by acting out dreams, which may include shouting, kicking and punching during sleep.Anelyssa D'Abreu, Associate Professor of Neurology, University of VirginiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1908702023-02-23T13:15:04Z2023-02-23T13:15:04ZImagination makes us human – this unique ability to envision what doesn’t exist has a long evolutionary history<figure><img src="https://images.theconversation.com/files/510729/original/file-20230216-24-yo82dh.jpg?ixlib=rb-1.1.0&rect=102%2C53%2C3346%2C2522&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Your brain can imagine things that haven't happened or that don't even exist.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/constellation-of-you-royalty-free-image/487364203">agsandrew/iStock via Getty Images Plus</a></span></figcaption></figure><p>You can easily picture yourself riding a bicycle across the sky even though that’s not something that can actually happen. You can envision yourself doing something you’ve never done before – like water skiing – and maybe even imagine a better way to do it than anyone else.</p>
<p>Imagination involves creating a mental image of something that is not present for your senses to detect, or even something that isn’t out there in reality somewhere. Imagination is one of the key abilities that make us human. But where did it come from?</p>
<p><a href="https://scholar.google.com/citations?user=Ury0hsMAAAAJ&hl=en&oi=ao">I’m a neuroscientist</a> who studies how children acquire imagination. I’m especially interested in the neurological mechanisms of imagination. Once we identify what brain structures and connections are necessary to mentally construct new objects and scenes, scientists like me can look back over the course of evolution to see when these brain areas emerged – and potentially gave birth to the first kinds of imagination.</p>
<h2>From bacteria to mammals</h2>
<p>After <a href="https://doi.org/10.1038/s41586-019-1436-4">life emerged on Earth</a> around 3.4 billion years ago, organisms gradually became more complex. Around 700 million years ago, neurons organized into <a href="https://doi.org/10.1242/jeb.110692">simple neural nets</a> that then <a href="https://doi.org/10.1101/gr.874803">evolved into the brain and spinal cord</a> around 525 million years ago.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510737/original/file-20230216-20-wy383x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Velociraptor chasing a furry critter" src="https://images.theconversation.com/files/510737/original/file-20230216-20-wy383x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510737/original/file-20230216-20-wy383x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510737/original/file-20230216-20-wy383x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510737/original/file-20230216-20-wy383x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510737/original/file-20230216-20-wy383x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510737/original/file-20230216-20-wy383x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510737/original/file-20230216-20-wy383x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It was to mammals’ advantage to hide out while cold-blooded dinosaurs hunted during the day.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/velociraptor-chasing-a-rat-sized-mammal-royalty-free-illustration/168839736">Daniel Eskridge/Stocktrek Images via Getty Images</a></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1111/j.1469-185X.2009.00094.x">Eventually dinosaurs evolved around 240 million</a> years ago, with <a href="https://doi.org/10.1038/s41586-022-04963-z">mammals emerging a few million years later</a>. While they shared the landscape, dinosaurs were very good at catching and <a href="https://doi.org/10.1080/02724634.2022.2144337">eating small, furry mammals</a>. Dinosaurs were cold-blooded, though, and, like modern cold-blooded reptiles, could only move and hunt effectively <a href="https://doi.org/10.1126/science.1253143">during the daytime when it was warm</a>. To avoid predation by dinosaurs, mammals stumbled upon a solution: <a href="https://doi.org/10.1016/j.ympev.2014.05.016">hide underground during the daytime</a>.</p>
<p>Not much food, though, grows underground. To eat, mammals had to travel above the ground – but the safest time to forage was at night, when dinosaurs were less of a threat. <a href="https://doi.org/10.1038/s41586-022-04963-z">Evolving to be warm-blooded</a> meant mammals could move at night. That solution came with a trade-off, though: Mammals had to eat a lot more food than dinosaurs per unit of weight <a href="https://doi.org/10.1111/brv.12280">in order to maintain their high metabolism</a> and to support their constant inner body temperature around 99 degrees Fahrenheit (37 degrees Celsius).</p>
<p>Our mammalian ancestors had to find <a href="https://doi.org/10.1126/science.1061967">10 times more food</a> during their short waking time, and they had to find it in the dark of night. How did they accomplish this task?</p>
<p>To optimize their foraging, mammals developed a new system to efficiently memorize places where they’d found food: linking the part of the brain that records sensory aspects of the landscape – how a place looks or smells – to the part of the brain that controls navigation. They encoded features of the landscape in the neocortex, the outermost layer of the brain. They encoded navigation in the entorhinal cortex. And the <a href="https://doi.org/10.1038/s41593-018-0189-y">whole system was interconnected</a> by the brain structure called the hippocampus. <a href="https://doi.org/10.1002/hipo.20205">Humans still use this memory system</a> for remembering objects and past events, such as your car and where you parked it.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510740/original/file-20230216-14-qjt96p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="two bits of human brain are highlighted, one on each side" src="https://images.theconversation.com/files/510740/original/file-20230216-14-qjt96p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510740/original/file-20230216-14-qjt96p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510740/original/file-20230216-14-qjt96p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510740/original/file-20230216-14-qjt96p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510740/original/file-20230216-14-qjt96p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510740/original/file-20230216-14-qjt96p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510740/original/file-20230216-14-qjt96p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An interior brain structure called the hippocampus helps synthesize different kinds of information to create memories.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/hippocampus-of-the-brain-illustration-royalty-free-illustration/1220616079">Sebastian Kaulitzki/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1016/j.conb.2020.03.014">Groups of neurons</a> in the neocortex encode these memories of objects and past events. Remembering a thing or an episode <a href="https://doi.org/10.1037/a0017937">reactivates the same neurons</a> that initially encoded it. All mammals likely can recall and re-experience previously encoded objects and events by reactivating these groups of neurons. This neocortex-hippocampus-based memory system that evolved 200 million years ago became the first key step toward imagination. </p>
<p>The next building block is the capability to construct a “memory” that hasn’t really happened.</p>
<h2>Involuntary made-up ‘memories’</h2>
<p>The simplest form of imagining new objects and scenes happens in dreams. These vivid, bizarre involuntary fantasies are associated in people with the rapid eye movement (REM) stage of sleep.</p>
<p>Scientists hypothesize that species whose rest includes periods of REM sleep <a href="https://doi.org/10.1038/nrn2716">also experience dreams</a>. Marsupial and placental mammals do have REM sleep, but the egg-laying mammal the echidna does not, suggesting that this stage of the sleep cycle <a href="https://www.worldcat.org/title/317118257">evolved after these evolutionary lines diverged</a> 140 million years ago. In fact, recording from specialized neurons in the brain called <a href="https://doi.org/10.1146/annurev.neuro.31.061307.090723">place cells</a> demonstrated that animals can “dream” of going <a href="https://doi.org/10.7554/eLife.06063">places they’ve never visited before</a>.</p>
<p>In humans, solutions found during dreaming can <a href="https://doi.org/10.1038/nature02223">help solve problems</a>. There are numerous examples of scientific and engineering solutions spontaneously visualized during sleep.</p>
<p>The neuroscientist Otto Loewi dreamed of an experiment that proved nerve impulses are <a href="https://www.nobelprize.org/prizes/medicine/1936/loewi/facts/">transmitted chemically</a>. He immediately went to his lab to perform the experiment – later receiving the Nobel Prize for this discovery.</p>
<p>Elias Howe, the inventor of the first sewing machine, claimed that the main innovation, placing the thread hole near the tip of the needle, <a href="https://dreamsocial.co/famous-dreams-sewing-machine/">came to him in a dream</a>. </p>
<p>Dmitri Mendeleev described seeing in a dream “<a href="https://doi.org/10.1038/35046170">a table where all the elements fell into place as required</a>. Awakening, I immediately wrote it down on a piece of paper.” And that was the periodic table.</p>
<p>These discoveries were enabled by the same mechanism of involuntary imagination first acquired by mammals 140 million years ago.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/510741/original/file-20230216-14-qmauaf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="young professionals looking at glass wall with post-it notes" src="https://images.theconversation.com/files/510741/original/file-20230216-14-qmauaf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/510741/original/file-20230216-14-qmauaf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/510741/original/file-20230216-14-qmauaf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/510741/original/file-20230216-14-qmauaf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/510741/original/file-20230216-14-qmauaf.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/510741/original/file-20230216-14-qmauaf.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/510741/original/file-20230216-14-qmauaf.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Intentionally brainstorming ideas depends on being able to control your imagination.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/diverse-businesspeople-smiling-while-having-a-royalty-free-image/1453986826">Goodboy Picture Company/E+ via Getty Images</a></span>
</figcaption>
</figure>
<h2>Imagining on purpose</h2>
<p>The difference between voluntary imagination and involuntary imagination is analogous to the difference between voluntary muscle control and muscle spasm. Voluntary muscle control allows people to deliberately combine muscle movements. Spasm occurs spontaneously and cannot be controlled.</p>
<p>Similarly, voluntary imagination allows people to deliberately combine thoughts. When asked to mentally combine two identical right triangles along their long edges, or hypotenuses, you envision a square. When asked to mentally cut a round pizza by two perpendicular lines, you visualize four identical slices.</p>
<p>This deliberate, responsive and reliable capacity to combine and recombine mental objects is called prefrontal synthesis. It relies on the ability of the prefrontal cortex located at the very front of the brain to control the rest of the neocortex.</p>
<p>When did our species acquire the ability of prefrontal synthesis? Every artifact dated before 70,000 years ago could have been made by a creator who lacked this ability. On the other hand, starting about that time there are various archeological artifacts unambiguously indicating its presence: composite figurative objects, such as <a href="https://doi.org/10.1038/425007a">lion-man</a>; <a href="https://doi.org/10.1016/j.jas.2007.11.006">bone needles with an eye</a>; <a href="https://doi.org/10.1016/j.jas.2011.04.001">bows and arrows</a>; <a href="https://doi.org/10.1016/j.jhevol.2012.03.003">musical instruments</a>; <a href="https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/gea.20163">constructed dwellings</a>; <a href="https://doi.org/10.1177/0392192107077649">adorned burials suggesting the beliefs in afterlife</a>, and many more. </p>
<p>Multiple types of archaeological artifacts unambiguously associated with prefrontal synthesis appear simultaneously around 65,000 years ago in multiple geographical locations. This abrupt change in imagination has been characterized by historian Yuval Harari as the “<a href="https://www.penguin.co.uk/books/437186/sapiens-by-yuval-noah-harari/9781784873646">cognitive revolution</a>.” Notably, <a href="https://doi.org/10.1016/j.ajhg.2009.05.001">it approximately coincides with</a> the largest <a href="https://doi.org/10.1086/375120"><em>Homo sapiens</em>‘ migration out of Africa</a>.</p>
<p><a href="https://doi.org/10.1098/rspb.2009.1473">Genetic analyses suggest</a> that a few individuals acquired this prefrontal synthesis ability and then spread their genes far and wide by eliminating other contemporaneous males with the use of an imagination-enabeled strategy and newly developed weapons.</p>
<p>So it’s been a journey of many millions of years of evolution for our species to become equipped with imagination. Most nonhuman mammals have potential for imagining what doesn’t exist or hasn’t happened involuntarily during REM sleep; only humans can voluntarily conjure new objects and events in our minds using prefrontal synthesis.</p><img src="https://counter.theconversation.com/content/190870/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrey Vyshedskiy does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>By learning what parts of the brain are crucial for imagination to work, neuroscientists can look back over hundreds of millions of years of evolution to figure out when it first emerged.Andrey Vyshedskiy, Professor of Neuroscience, Boston UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1907062022-09-21T09:41:41Z2022-09-21T09:41:41ZQuality of sleep matters for your health, not just the duration – new study<figure><img src="https://images.theconversation.com/files/485565/original/file-20220920-3857-b2boni.jpg?ixlib=rb-1.1.0&rect=0%2C18%2C6281%2C4156&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/lack-sleep-concept-portrait-tired-young-2015030525">Prostock-studio/Shutterstock</a></span></figcaption></figure><p>The American National Sleep Foundation recommends that adults get <a href="https://www.sleepfoundation.org/how-sleep-works/how-much-sleep-do-we-really-need#:%7E:text=National%20Sleep%20Foundation%20guidelines1,to%208%20hours%20per%20night.">seven to nine hours</a> sleep each night. Many people fall short of this because they restrict their sleep to make way for a change in their life, such as having a new baby, taking on a new job that starts much earlier, or moving to a new home that is further from work. Our <a href="https://academic.oup.com/sleep/advance-article/doi/10.1093/sleep/zsac222/6702165">latest research</a> shows the detrimental effect this can have on some people’s health – some, but not all. </p>
<p>Our study, published in the journal Sleep, shows that adults who restrict their sleep by two or more hours each night are more likely to suffer a respiratory illness, but only in those reporting poor sleep quality. Adults who don’t get the recommended amount of sleep but report getting a good night’s sleep seem to be protected from respiratory illness, including colds, flu and COVID.</p>
<p>Good sleep quality is associated with a stage of sleep known as “slow-wave sleep”. </p>
<p>There are four sleep stages, distinguished by patterns of brain activity, eye movements and muscle tone. On a normal night’s sleep, these four stages cycle every 90 minutes or so. Stages one to three are characterised as non-rapid eye movement sleep (non-REM) and stage four is REM sleep, where your eyes move rapidly behind your eyelids. Non-REM sleep comprises light sleep in stages one and two through to deep sleep in stage three. This deep sleep in stage three is slow-wave sleep.</p>
<p>Slow-wave sleep helps you feel refreshed when you wake up and is linked to how people rate their sleep quality.</p>
<h2>Individual sleep needs matter</h2>
<p>Research shows that adults who usually get less than seven to nine hours of sleep are more likely to suffer ill health. <a href="https://pubmed.ncbi.nlm.nih.gov/34779405/">Obesity, type 2 diabetes</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/28477772/">cardiovascular disease</a> and respiratory infection are all more common in habitual short sleepers – those sleeping less than six hours a night. </p>
<p>These findings provide a solid foundation for the one-size-fits-all sleep duration recommendation. Yet sleeping for seven to nine hours each night is probably not necessary for everyone to achieve optimal health. People may differ in their sleep needs.</p>
<figure class="align-center ">
<img alt="Man in army uniform lying on bed." src="https://images.theconversation.com/files/485567/original/file-20220920-21-dak48c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485567/original/file-20220920-21-dak48c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485567/original/file-20220920-21-dak48c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485567/original/file-20220920-21-dak48c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485567/original/file-20220920-21-dak48c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485567/original/file-20220920-21-dak48c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485567/original/file-20220920-21-dak48c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Basic training is an ideal time to study the effects of restricted sleeping on health.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/closeup-shot-soldier-sleeping-bed-1754856239">Wirestock Creators/Shutterstock</a></span>
</figcaption>
</figure>
<p>Our new research was inspired by the <a href="https://pubmed.ncbi.nlm.nih.gov/22215923/">findings of a 2012 study</a> showing that pneumonia risk was increased among short sleepers (less than five hours sleep a night). However, the risk of pneumonia was only increased in short sleepers who perceived they had inadequate sleep. The risk of getting pneumonia was not increased in short-sleepers who reported adequate sleep.</p>
<p>In our study, we wanted to know whether sleep restriction increases the risk of getting a respiratory infection and whether good quality sleep protects against respiratory infection during a time of sleep restriction. </p>
<p>Civilians entering basic military training offered us an opportunity to answer these questions under standardised living and working conditions, such as diet and physical activity. Sleep restriction during military training is largely because of early morning awakening.</p>
<h2>Testing in military recruits</h2>
<p>We recruited 1,318 healthy adults (68% males) and asked them to report their sleep duration and quality during civilian life and at the start and end of 12 weeks of training. We defined sleep restriction as a two-or-more-hour reduction in sleep each night compared with civilian life. Respiratory infections were diagnosed by a doctor.</p>
<p>We found that sleep restriction increases respiratory infection, but only in those with poor quality sleep.</p>
<p>On average, recruits slept two hours less during military training than in civilian life. Despite this, over half of those with sleep restriction rated their sleep as good quality.</p>
<p>Recruits who experienced sleep restriction during training were three times more likely to suffer respiratory infection. This finding remained after taking into account factors that influence the risk of respiratory infection, such as season and smoking. But that wasn’t the end of the story.</p>
<p>Further analysis of the data revealed that sleep restriction only increased respiratory infection in recruits reporting poor sleep quality. Good sleep quality was associated with protection against respiratory infection.</p>
<p>The next step is to investigate whether improving sleep quality translates to reduced respiratory infection in those who can’t afford the recommended seven to nine hours of sleep each night.</p>
<h2>Ways to improve your sleep quality</h2>
<p>Here are five ways to <a href="https://sleepeducation.org/healthy-sleep/healthy-sleep-habits/">improve your sleep quality</a> that may boost your resistance to respiratory infections:</p>
<ul>
<li>Adopt a consistent sleep schedule (similar bed and wake time), including weekends.</li>
<li>Avoid large meals, caffeine and alcohol close to bedtime.</li>
<li>Ensure the bed and pillow are comfortable and that the room is cool, dark and quiet.</li>
<li>Establish a relaxing bedtime routine. Go screen-free 30 minutes before bedtime and go to bed when you feel sleepy. </li>
<li>Exercise during the day as it may help you fall asleep.</li>
</ul><img src="https://counter.theconversation.com/content/190706/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Neil Walsh receives funding from MOD, UK. </span></em></p>Even during periods of restricted sleep, people who report good sleep quality are three times less likely to get a respiratory infection.Neil Walsh, Professor, Applied Physiology, Liverpool John Moores UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1890232022-08-25T18:00:51Z2022-08-25T18:00:51ZRapid eye movements in sleeping mice match where they are looking in their dreams, new research finds<figure><img src="https://images.theconversation.com/files/480907/original/file-20220824-14-42pff1.jpg?ixlib=rb-1.1.0&rect=0%2C67%2C1732%2C1560&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Do your eyes play a role in where you look in your dreams?</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/you-are-being-watched-royalty-free-image/1256110077">PM Images/DigitalVision via Getty Images</a></span></figcaption></figure><p>Does rapid eye movement during sleep reveal where you’re looking at in the scenery of dreams, or are they simply the result of random jerks of our eye muscles? Since the <a href="https://doi.org/10.1126/science.118.3062.273">discovery of REM sleep in the early 1950s</a>, the significance of these rapid eye movements has intrigued and fascinated scores of scientists, psychologists and philosophers. <a href="https://www.ninds.nih.gov/health-information/patient-caregiver-education/brain-basics-understanding-sleep#2">REM sleep</a>, as the name implies, is a period of sleep when your eyes move under your closed eyelids. It’s also the period when you experience vivid dreams.</p>
<p>We are researchers who study how the brain <a href="https://www.hhmi.org/scientists/massimo-scanziani">processes sensory information</a> during <a href="https://scholar.google.com/citations?user=xLflzyAAAAAJ&hl=en">wakefulness and sleep</a>. In our <a href="https://www.science.org/doi/10.1126/science.abp8852">recently published study</a>, we found that the eye movements you make while you sleep may reflect where you’re looking in your dreams.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/rMHus-0wFSo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Dreams occur during the REM stage of sleep.</span></figcaption>
</figure>
<h2>Measuring dreams</h2>
<p>Past <a href="https://doi.org/10.1037/h0048189">studies</a> <a href="https://doi.org/10.1001/archpsyc.1962.01720040001001">have</a> <a href="https://doi.org/10.1038/224613a0">attempted</a> to address this question by monitoring the eye movements of people as they slept and waking them up to ask what they were dreaming. The goal was to find a possible connection between the content of a dream just before waking up (say, a car coming in from the left) and the direction the eyes moved at that moment.</p>
<p>Unfortunately, these studies have led to contradictory results. It could be that some participants inaccurately reported dreams, and it’s technically difficult to match a given eye movement to a specific moment in a self-reported dream. </p>
<p>We decided to bypass the problem of dream self-reporting. Instead, we used a more objective way to measure dreams: the electrical activity of a sleeping mouse brain.</p>
<p><a href="https://doi.org/10.1016/j.conb.2021.08.004">Mice, like humans and many other animals</a>, also experience REM sleep. Additionally, they have a sort of internal compass in their brains that gives them a sense of <a href="http://www.scholarpedia.org/article/Head_direction_cells">head direction</a>. When the mouse is awake and running around, the electrical activity of this internal compass precisely reports its head direction, or “heading,” as it moves in its environment. </p>
<p>Interestingly, a <a href="https://doi.org/10.1038/nn.3968">previous study</a> showed that this internal compass is active during REM sleep. But instead of reporting the actual, fixed head direction of the motionless sleeping mouse, the internal compass kept moving as if the mouse were awake, running around in the virtual environment of its dreams.</p>
<p>Eye movements and head movements are <a href="https://doi.org/10.7554/eLife.57458">tightly coupled</a> <a href="https://doi.org/10.1016/j.cub.2020.04.042">during wakefulness</a>. This means that when people and mice shift their gaze, their heads and eyes turn in the same direction. We reasoned that if eye movements during REM sleep reveal gaze shifts in the world of dreams, those eye movements should occur at the same time and in the same direction as changes in heading in the sleeping mouse’s brain. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/480664/original/file-20220823-8395-tz6whm.jpg?ixlib=rb-1.1.0&rect=36%2C25%2C1780%2C1073&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up of person's closed eyes looking to the left and to the right under their eyelids" src="https://images.theconversation.com/files/480664/original/file-20220823-8395-tz6whm.jpg?ixlib=rb-1.1.0&rect=36%2C25%2C1780%2C1073&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/480664/original/file-20220823-8395-tz6whm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=366&fit=crop&dpr=1 600w, https://images.theconversation.com/files/480664/original/file-20220823-8395-tz6whm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=366&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/480664/original/file-20220823-8395-tz6whm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=366&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/480664/original/file-20220823-8395-tz6whm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=459&fit=crop&dpr=1 754w, https://images.theconversation.com/files/480664/original/file-20220823-8395-tz6whm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=459&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/480664/original/file-20220823-8395-tz6whm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=459&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Your eyes may be watching something in your dreams when they move during sleep.</span>
<span class="attribution"><span class="source">Massimo Scanziani</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>To test this hypothesis, we measured rapid eye movements, or <a href="https://eyewiki.aao.org/Saccade">saccades</a>, when mice were awake and mapped this to the electrical activity of their brain’s internal compass. We then monitored the eye movements of sleeping mice during REM sleep with miniature cameras placed in front of both eyes. Because mice often do not completely close their eyelids while asleep, this allowed us to precisely measure the direction of their eye movements. As when the mice were awake, we recorded the electrical activity of their brain’s internal compass to decode changes in heading during REM sleep.</p>
<p>Strikingly, we discovered that eye movement direction in sleeping mice precisely matched changes in heading direction, very much like gaze shifts in mice that are awake. This meant that eye movements during REM sleep may disclose gaze shifts in the virtual world of dreams, providing a window into the cognitive processes occurring in the dreaming brain.</p>
<h2>The dreaming brain</h2>
<p>Our study shows that, during REM sleep, the part of the brain that controls the sense of head direction coordinates with the part that controls eye movements. This finding may just be the tip of the iceberg on how distinct parts of the brain function together as a whole during sleep. </p>
<p>If other brain areas also work together during REM sleep, like those responsible for sensory perception, emotion or sense of place, this overall coordination between parts may well be the basis for vivid and realistic dream experiences.</p>
<p>When you are awake, your <a href="http://www.scholarpedia.org/article/Head_direction_cells">sense of head direction</a> relies on information gathered from several areas of the brain involved with your sense of balance and sight, among others, which are active when you move around. Our study brings up an important question: What does your sense of head direction rely on during REM sleep, when you aren’t moving? </p>
<p>Our next steps are to figure out what moves the brain’s internal compass during REM sleep, how it moves with the eyes and how different senses work together to generate the realistic experience of dreams.</p><img src="https://counter.theconversation.com/content/189023/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Yuta Senzai has received funding from the Japan Society for the Promotion of Science.</span></em></p><p class="fine-print"><em><span>Massimo Scanziani receives funding from the National Institute of Health and the Howard Hughes Medical Institute</span></em></p>Why your eyes move during the REM stage of sleep has puzzled scientists for years. Researchers measured mice brains to look for a possible explanation.Yuta Senzai, Postdoctoral Scholar in Physiology, University of California, San FranciscoMassimo Scanziani, Professor of Physiology, University of California, San FranciscoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1791562022-03-18T11:28:02Z2022-03-18T11:28:02Z‘Sleeping on it’ helps you better manage your emotions and mental health – here’s why<figure><img src="https://images.theconversation.com/files/453020/original/file-20220318-13-ulamgg.jpg?ixlib=rb-1.1.0&rect=44%2C0%2C4901%2C3257&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A bad sleep can make you more reactive to stressful situations the next day.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/people-bedtime-rest-concept-indian-man-1917162575">Syda Productions/ Shutterstock</a></span></figcaption></figure><p>Instead of lying awake worrying, we’re often told to “sleep on it” when making decisions both big and small. And there’s actually a scientific basis for this advice. Sleep can influence our response to emotional situations, and helps us to manage our mental health.</p>
<p>To understand why sleep and emotions are so connected, it’s important to first understand what happens in the brain when we encounter something emotive.</p>
<p>Two main brain regions <a href="https://www.sciencedirect.com/science/article/pii/0149763494000534">interact to create emotional responses</a>. The first is the limbic system, which is located deep in our brain. This acts as our emotion centre, quickly evaluating a situation and helping us to decide how to react. Historically, this region may have been important for <a href="https://deepblue.lib.umich.edu/bitstream/handle/2027.42/31354/0000265.pdf?sequence=1">humanity’s survival</a>, as it helps us react quickly in certain situations – if we encounter a dangerous predator, for example. </p>
<p>But most of the time we need to adjust our initial emotional response. This is where the second region – the prefrontal cortex – comes in. Located just behind our forehead, the prefrontal cortex helps us to increase or decrease our emotional responses as necessary. So if we see a predator (such as a bear) in the zoo, the prefrontal cortex tells us we don’t need to panic because it’s in an enclosure. </p>
<p>These regions need to be well-connected in order to effectively generate and adjust our emotional responses. This is where sleep comes in. When we’re sleep deprived, <a href="https://www.sciencedirect.com/science/article/pii/S0960982207017836#bib6">the connections between these areas weaken</a>, making the reaction in the limbic system stronger. Sleep loss not only increases our reaction to stressful events during the day, it also makes these reactions harder to change. This may be particularly pronounced <a href="https://www.frontiersin.org/articles/10.3389/fnbeh.2012.00025/full">if you lose REM (rapid eye movement) sleep</a>. </p>
<p>Studies show that getting poor sleep makes us more likely to choose <a href="https://www.sciencedirect.com/science/article/abs/pii/S002239561730777X">less effective ways of managing our emotions</a> which could have a knock-on effect for our mental health. Imagine you’re experiencing a difficult work problem. If you’re well rested, you are more likely to be able to <a href="https://link.springer.com/article/10.3758/s13421-012-0256-7">effectively problem solve</a>, fixing the issue. But if you’re sleep deprived, you might <a href="https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/smi.3057">avoid dealing with the problem</a>. Over time, this could have a negative effect on wellbeing.</p>
<figure class="align-center ">
<img alt="A stressed woman screams at her computer in a busy office." src="https://images.theconversation.com/files/453021/original/file-20220318-15-14lqlji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453021/original/file-20220318-15-14lqlji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453021/original/file-20220318-15-14lqlji.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453021/original/file-20220318-15-14lqlji.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453021/original/file-20220318-15-14lqlji.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453021/original/file-20220318-15-14lqlji.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453021/original/file-20220318-15-14lqlji.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Poor sleep makes us less able to manage our emotions.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/emotional-business-lady-shouting-her-laptop-653550538">Alex from the Rock/ Shutterstock</a></span>
</figcaption>
</figure>
<p>Sleep is also crucial for processing and consolidating memories from our day. When we have emotional experiences, sleep both helps us remember these events and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2890316/?__hstc=52210678.a0ddae8e24bce7c0af0efdd41a653140.1454889600079.1454889600080.1454889600081.1&__hssc=52210678.1.1454889600082&__hsfp=3972014050">remove the associated feelings</a>. This happens in REM sleep, when activity in most brain regions is similar to when we’re awake. By reactivating memories during REM sleep, the associated feelings can be removed from the content of the memory. This is why “sleeping on it” really can help you feel better in the morning. Indeed, studies have shown that, over time, improving sleep can lead to <a href="https://doi.org/10.1111/jsr.13451">less anxiety</a>, <a href="https://www.sciencedirect.com/science/article/pii/S1087079221001416">depression, and stress</a>, and <a href="https://jeps.efpsa.org/articles/10.5334/jeps.434/">increased life satisfaction</a>.</p>
<h2>A good night’s sleep</h2>
<p>If you want to keep your emotions and mental health in check, here are the best ways to get a <a href="https://www.nhs.uk/live-well/sleep-and-tiredness/how-to-get-to-sleep/">good night’s sleep</a>: </p>
<ol>
<li><p><strong>Maintain a consistent bedtime and wake time</strong> – even on your days off. This helps your body clock get into a routine, improving your sleep. Having a big shift in sleep time between your work and free days is known as “<a href="https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1011.9782&rep=rep1&type=pdf">social jetlag</a>”, which can be associated with <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6397070/">increased anxiety</a>. </p></li>
<li><p><strong>Seek out natural light in the morning and avoid blue light in the evening.</strong> Our body clock is strongly affected by light. It impacts a part of the brain called the supra-chiasmatic nucleus, which releases a sleep hormone called melatonin. Getting natural light in the morning helps us to suppress melatonin, which <a href="https://orbi.uliege.be/bitstream/2268/171514/1/Gabel_CI_2013.pdf">improves our mood and makes us feel more alert</a>. The blue light found in electronic devices also <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1600-079X.2011.00970.x">minimises melatonin</a>. This means that using electronics in the evening can result in it taking longer for us to feel sleepy. So we recommend that you turn them off or set them to “night time mode” an hour before you go to bed. </p></li>
<li><p><strong>Avoid certain substances</strong> – such as alcohol, caffeine and nicotine. Caffeine and nicotine are stimulants, which can interfere with our body’s <a href="https://onlinelibrary.wiley.com/doi/pdf/10.1111/ajad.12291?casa_token=TwGeoMomWv8AAAAA:gjXLell1o2buRFt7twVAndu-GIE27Njt65JCuGDxAkl6pHUGI1vju9JTWrOal3obT7inAnP6i1CHt4fg">drive to sleep</a>. It’s best to avoid these, particularly in the afternoon and evening as our body gets ready for sleep. Alcohol also changes the structure of our sleep, making us more likely to wake up <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6707127/">during the night</a>. Studies also show using alcohol daily can decrease sleep quality, especially for <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6554008/">people with anxiety</a>. </p></li>
<li><p><strong>Allow yourself time to wind down before bed.</strong> Make sure your bedroom is comfortable, cool, quiet and dark to minimise chances of being disturbed. Before bed, try using relaxation or mindfulness techniques, which have been linked with both <a href="https://doi.org/10.1111/nyas.13996">better sleep quality</a> and better <a href="https://www.sciencedirect.com/science/article/pii/S0272735815300623">overall mental health</a>. </p></li>
</ol>
<p>Getting a good night’s sleep can work wonders for improving our mental health. But it doesn’t stop there. Sleeping well can also improve our <a href="https://www.nature.com/articles/nrn2762">memory</a>, <a href="https://academic.oup.com/sleep/article/38/12/1935/2417960?login=false">attention</a> and other <a href="https://wires.onlinelibrary.wiley.com/doi/pdf/10.1002/wcs.52?casa_token=IE4BddseQZ8AAAAA%3AHN-TiESS6SCCuDTyPoLj-ZLxl4CwcVBZV9I5Irwq7AIAH-YC7LV0GdLszvAImlQE5ntHh1aDGAi51NkI">thought processes</a>. It also benefits several aspects of our physical health, including our <a href="https://onlinelibrary.wiley.com/doi/pdfdirect/10.1038/oby.2012.62">weight</a> and <a href="https://doi.org/10.1016/j.cpcardiol.2005.07.002">heart</a>, making sleep an important priority for all aspects of our wellbeing.</p><img src="https://counter.theconversation.com/content/179156/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joanne Bower does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sleep and mental health have a well established relationship.Joanne Bower, Lecturer in Psychology, University of East AngliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1769772022-02-22T19:10:00Z2022-02-22T19:10:00ZNew survey shows your relationship status tallies with how well you sleep<figure><img src="https://images.theconversation.com/files/447437/original/file-20220221-19-iruu6e.jpg?ixlib=rb-1.1.0&rect=84%2C8%2C5523%2C3724&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-feet-couple-on-bed-318022337">Shutterstock</a></span></figcaption></figure><p>A <a href="https://cdn.publisher.gn1.link/sleepscience.org.br/pdf/v15nspea10.pdf">new survey</a> of Australian adults has found your relationship status can impact how well you sleep. </p>
<p>We know based on <a href="https://psycnet.apa.org/record/2016-57347-017">previous research</a> that sleeping next to someone can help you sleep better – but this is the first study to look at how the type of relationship you’re in might impact your sleep. </p>
<p>We found that people who live with a regular partner tend to fall asleep faster than people who have occasional or casual partners, or who are single. It’s not all bad news for people who aren’t in an ongoing relationship though – the amount of sleep people got overnight wasn’t related to relationship status. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/how-the-brain-tunes-in-to-unfamiliar-voices-while-youre-sleeping-and-why-it-matters-175018">How the brain tunes in to unfamiliar voices while you're sleeping – and why it matters</a>
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</em>
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<h2>Perchance to dream and stay healthy</h2>
<p>It’s generally <a href="https://pubmed.ncbi.nlm.nih.gov/29073412/">recommended</a> you should get seven to nine hours of sleep a night. However, about 40% of Australians <a href="https://pubmed.ncbi.nlm.nih.gov/28346149/">report</a> inadequate sleep. </p>
<p>Not getting enough sleep, or having poor quality sleep, can lead to a range of health problems – such as <a href="https://pubmed.ncbi.nlm.nih.gov/28477772/">poor heart health</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/30179863/">stomach problems</a>, <a href="https://psycnet.apa.org/record/2017-04295-001">poor mental health</a>, and a greater risk of <a href="https://pubmed.ncbi.nlm.nih.gov/33383522/">accident or injury</a>. </p>
<p>Lots of things can affect how well you sleep – like work worries, family responsibilities and health. Existing research also tells us sleeping next to someone can impact our sleep. Due to a range of psychological and evolutionary factors, such as the need for strong social bonds to feel safe, it seems sleeping next to someone <a href="https://www.frontiersin.org/articles/10.3389/fpsyt.2020.00583/full">results in better sleep</a>, and how well you sleep is <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2950886/">linked with your relationship quality</a>. Getting along well with your partner might lead to a better night of sleep – and vice versa! </p>
<p>However, no previous research investigated how relationship status might affect your sleep. We <a href="https://cdn.publisher.gn1.link/sleepscience.org.br/pdf/v15nspea10.pdf">asked nearly 800 Australian adults</a> about their relationship status and to rate their sleep using a shorter version of the <a href="https://www.sciencedirect.com/science/article/abs/pii/0165178189900474">Pittsburgh Sleep Quality Index</a>, which has been verified as a valid sleep measure.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/447463/original/file-20220221-18-spb52z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="older couple jump on bed with joy" src="https://images.theconversation.com/files/447463/original/file-20220221-18-spb52z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/447463/original/file-20220221-18-spb52z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/447463/original/file-20220221-18-spb52z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/447463/original/file-20220221-18-spb52z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/447463/original/file-20220221-18-spb52z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/447463/original/file-20220221-18-spb52z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/447463/original/file-20220221-18-spb52z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Couples that sleep well together, well, you know …</span>
<span class="attribution"><a class="source" href="https://image.shutterstock.com/image-photo/love-lives-forever-senior-couple-600w-1062165887.jpg">Shutterstock</a></span>
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<h2>Casual partners keep us up at night</h2>
<p>Our <a href="https://cdn.publisher.gn1.link/sleepscience.org.br/pdf/v15nspea10.pdf">study</a>, to be published in the March edition of the <a href="https://www.sciencedirect.com/journal/sleep-science">Sleep Science</a> journal, finds it takes people who have casual or occasional partners just over ten minutes longer to fall asleep than people who live with a regular partner. </p>
<p>Ten minutes might not sound like a long time – but <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3208841/">studies show</a> just four to eight minutes can be the difference between people with insomnia (seen as hyperarousal with physiological measures like increased metabolic rate, higher body temperature, altered heart rate and activity in the brain) and healthy sleepers. </p>
<p>When we break this down by gender in our study, we see women are much more likely to be affected by relationship status than men. Men fall asleep just as quickly when they have a casual partner compared with a regular, live-in partner.</p>
<p>These differences are only seen when we look at what is called “sleep latency” – the amount of time it takes from turning off the light to when you fall asleep. The other main measure – the total amount of sleep overnight – does not change depending on relationship status. People in our study in relationships (regardless of living situation) also report higher post-sex emotional satisfaction, and more frequent orgasms.</p>
<p>So, while you might feel like your sleep is worse because it takes a little longer to get to sleep, we don’t expect this to play out as major changes to daytime fatigue or sleepiness for people who are single or in casual relationships.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/447436/original/file-20220221-21-1qb38zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="two women in bed sheets" src="https://images.theconversation.com/files/447436/original/file-20220221-21-1qb38zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/447436/original/file-20220221-21-1qb38zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/447436/original/file-20220221-21-1qb38zp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/447436/original/file-20220221-21-1qb38zp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/447436/original/file-20220221-21-1qb38zp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/447436/original/file-20220221-21-1qb38zp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/447436/original/file-20220221-21-1qb38zp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Relationship status seems to have a greater impact on women’s sleep.</span>
<span class="attribution"><a class="source" href="https://image.shutterstock.com/image-photo/delighted-lesbians-feeling-happiness-while-600w-1933037432.jpg">Shutterstock</a></span>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-do-we-wake-around-3am-and-dwell-on-our-fears-and-shortcomings-169635">Why do we wake around 3am and dwell on our fears and shortcomings?</a>
</strong>
</em>
</p>
<hr>
<h2>Why is it so?</h2>
<p>A few things could explain why relationship status impacts sleep. </p>
<p>People who are in casual (or new) relationships might have greater physiological arousal (<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6135532/">racing hearts, breathing faster</a>), which can make it <a href="https://pubmed.ncbi.nlm.nih.gov/14998240/">harder to fall asleep</a>. People in new relationships that are still at the casual stage might experience more excitement or anxiety when sleeping next to their new partner – or they might be worrying about the status of their relationship. </p>
<p>On the other hand, being in an ongoing relationship may be associated with feelings of physical and emotional security, which can <a href="https://journals.sagepub.com/doi/abs/10.1177/1948550616662128">reduce physiological arousal</a> – and improve sleep. It’s possible we find it easier to sleep next to someone we trust because it is an evolutionary adaptation. That is, we feel safer from predators when sleeping in an environment we perceive to be “<a href="https://www.researchgate.net/publication/223347112_Sleeping_under_the_risk_of_predation">secure</a>”.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-this-love-or-an-arrhythmia-your-heart-really-can-skip-a-beat-when-youre-in-love-176537">Is this love ... or an arrhythmia? Your heart really can skip a beat when you're in love</a>
</strong>
</em>
</p>
<hr>
<h2>Now to bed … or beds</h2>
<p>If you were to go to the doctor and tell then you’re having trouble sleeping, chances are they would recommend strategies like improving your <a href="https://www.sleephealthfoundation.org.au/good-sleep-habits.html#:%7E:text=Go%20to%20another%20darkened%20room,being%20frustrated%20and%20not%20sleeping">sleep habits</a> or <a href="https://www.sleepfoundation.org/insomnia/treatment/cognitive-behavioral-therapy-insomnia">cognitive behavioural therapy</a> for insomnia. But these strategies don’t consider your relationship status. </p>
<p>Our findings suggest doctors could consider your relationship status as they work out how to help you get a better night’s sleep.</p>
<p>The next step for this research area is to understand how sleep changes when people are in the same bed as their partner or not. People in casual relationships may find falling asleep easier when they sleep alone, whereas people who live with their partners may not – we just don’t know yet. We also need objective data – from wearables or overnight brain activity monitoring – rather than surveys.</p><img src="https://counter.theconversation.com/content/176977/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Madeline Sprajcer does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>People – particularly women – take a little longer to fall asleep when they are next to a casual partner or single.Madeline Sprajcer, Lecturer in Psychology, CQUniversity AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1660062021-08-18T13:33:19Z2021-08-18T13:33:19ZBeing chased, losing your teeth or falling down? What science says about recurring dreams<figure><img src="https://images.theconversation.com/files/415867/original/file-20210812-20-14a9lhf.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1351%2C665&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In some cases, recurring dreams that emerge during childhood can even persist into adulthood. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/">(Shutterstock)</a></span></figcaption></figure><p>Having the same dream again and again is a well-known phenomenon — nearly <a href="https://psycnet.apa.org/record/1996-98816-016">two-thirds of the population</a> report having recurring dreams. Being chased, finding yourself naked in a public place or in the middle of a natural disaster, losing your teeth or forgetting to go to class for an entire semester are typical recurring scenarios in these dreams.</p>
<p>But where does the phenomenon come from? The science of dreams shows that recurring dreams may reflect unresolved conflicts in the dreamer’s life.</p>
<p>Recurring dreams <a href="https://doi.org/10.1023/A:1021152411010">often occur during times of stress</a>, or over long periods of time, sometimes several years or even a lifetime. Not only do these dreams have the same themes, they can also repeat the same narrative night after night. </p>
<p>Although the exact content of recurring dreams is unique to every individual, there are <a href="https://doi.org/10.1525/aa.1958.60.6.02a00110">common themes among individuals</a> and even among cultures and in different periods. For example, being chased, falling, being unprepared for an exam, arriving late or trying to do something repeatedly are among <a href="http://dreamscience.ca/en/documents/publications/_2003_Nielsen_Reprint_D_13_211-235_TDQ.pdf">the most prevalent scenarios</a>.</p>
<figure class="align-center ">
<img alt="A woman appears to levitate near a cliff" src="https://images.theconversation.com/files/410225/original/file-20210707-27-18yhy6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410225/original/file-20210707-27-18yhy6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410225/original/file-20210707-27-18yhy6z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410225/original/file-20210707-27-18yhy6z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410225/original/file-20210707-27-18yhy6z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410225/original/file-20210707-27-18yhy6z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410225/original/file-20210707-27-18yhy6z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Not all recurring dreams have a negative connotation. Some, such as being able to fly, can even have a euphoric effect.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>The majority of recurring dreams have negative content involving emotions such as fear, sadness, anger and guilt. More than half of recurring dreams involve a situation where the dreamer is in danger. But some recurring themes can also be positive, even euphoric, such as dreams where we discover new rooms in our house, erotic dreams or where we fly.</p>
<p>In some cases, recurring dreams that begin in childhood can persist into adulthood. These dreams may disappear for a few years, reappear in the presence of a new source of stress and then disappear again when the situation is over.</p>
<h2>Unresolved conflicts</h2>
<p>Why does our brain play the same dreams over and over again? Studies suggest that dreams, in general, help us <a href="https://doi.org/10.1037/a0016570">regulate our emotions</a> and adapt to stressful events. Incorporating emotional material into dreams may allow the dreamer to process a painful or difficult event.</p>
<p>In the case of recurrent dreams, repetitive content could represent an unsuccessful attempt to integrate these difficult experiences. <a href="https://www.proquest.com/docview/2490256841?pq-origsite=gscholar&fromopenview=true">Many theories</a> agree that recurring dreams are related to unresolved difficulties or conflicts in the dreamer’s life.</p>
<p>The presence of recurrent dreams has also been associated with <a href="https://doi.org/10.1037/0022-3514.50.3.612">lower levels of psychological well-being</a> and the presence of <a href="https://www.semanticscholar.org/paper/Dream-Content%2C-Dream-Recurrence-and-Well-Being%3A-A-a-Zadra-O%27Brien/af492efdd0bcdee15c4b5d743df9deb530e2daa0">symptoms of anxiety and depression</a>. These dreams tend to <a href="https://doi.org/10.1023/A:1021152411010">recur during stressful situations</a> and cease when the person <a href="https://psycnet.apa.org/record/1996-98816-016">has resolved their personal conflict</a>, which indicates improved well-being.</p>
<p>Recurrent dreams often metaphorically reflect the emotional concerns of the dreamers. For example, <a href="https://archive.org/details/dreamsnightmares0000hart_k4s6">dreaming about a tsunami</a> is common following trauma or abuse. This is a typical example of a metaphor that can represent emotions of helplessness, panic or fear experienced in waking life.</p>
<figure class="align-center ">
<img alt="Panicked man runs with his computer under his arm" src="https://images.theconversation.com/files/410226/original/file-20210707-21-drq5zk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410226/original/file-20210707-21-drq5zk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410226/original/file-20210707-21-drq5zk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410226/original/file-20210707-21-drq5zk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410226/original/file-20210707-21-drq5zk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410226/original/file-20210707-21-drq5zk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410226/original/file-20210707-21-drq5zk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Some people, during a stressful situation or when faced with a new challenge, may repeatedly dream that they are coming in late or unprepared for a math test, even years after they set foot in a school.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Similarly, being inappropriately dressed in one’s dream, being naked or not being able to find a toilet can all represent scenarios of embarrassment or modesty.</p>
<p><a href="https://psycnet.apa.org/record/2011-11210-004">These themes can be thought of as scripts</a> or ready-to-dream scenarios that provide us with a space where we can digest our conflicting emotions. The same script can be reused in different situations where we experience similar emotions. This is why some people, when faced with a stressful situation or a new challenge, may dream they’re showing up unprepared for a math exam, even years after they have set foot in a school. Although the circumstances are different, a similar feeling of stress or desire to excel can trigger the same dream scenario again.</p>
<h2>A continuum of repetition</h2>
<p>William Domhoff, an American researcher and psychologist, proposes the concept of a <a href="https://dreams.ucsc.edu/Library/domhoff_2000b.html">continuum of repetition in dreams</a>. At the extreme end, traumatic nightmares directly reproduce a lived trauma — one of the main symptoms of post-traumatic stress disorder.</p>
<p>Then there are recurring dreams where the same dream content is replayed in part or in its entirety. Unlike traumatic dreams, recurring dreams rarely replay an event or conflict directly but reflect it metaphorically through a central emotion.</p>
<p>Further along the continuum are the recurring themes in dreams. These dreams tend to replay a similar situation, such as being late, being chased or being lost, but the exact content of the dream differs from one time to the next, such as being late for a train rather than for an exam.</p>
<p>Finally, at the other end of the continuum, we find certain dream elements recurring in the dreams of one individual, such as characters, actions or objects. All these dreams would reflect, at different levels, an attempt to resolve certain emotional concerns.</p>
<p>Moving from an intense level to a lower level on the continuum of repetition is often a sign that a person’s psychological state is improving. For example, in the content of traumatic nightmares <a href="https://www.jstor.org/stable/43853181">progressive and positive changes</a> are often observed in people who have experienced trauma as they gradually overcome their difficulties.</p>
<h2>Physiological phenomena</h2>
<p>Why do the themes tend to be the same from person to person? One possible explanation is that some of these scripts have been preserved in humans due to the evolutionary advantage they bring. By <a href="https://doi.org/10.1017/S0140525X00004015">simulating a threatening situation</a>, the dream of being chased, for example, provides a space for a person to practise perceiving and escaping predators in their sleep.</p>
<figure class="align-center ">
<img alt="A young woman in bed holds her cheeks" src="https://images.theconversation.com/files/410227/original/file-20210707-15-16ptuyb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410227/original/file-20210707-15-16ptuyb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410227/original/file-20210707-15-16ptuyb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410227/original/file-20210707-15-16ptuyb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410227/original/file-20210707-15-16ptuyb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410227/original/file-20210707-15-16ptuyb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410227/original/file-20210707-15-16ptuyb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Some recurring dreams, such as losing one’s teeth, may be related to clenching one’s teeth during sleep or dental discomfort upon waking.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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</figure>
<p>Some common themes may also be explained, in part, by physiological phenomena that take place during sleep. A 2018 study by a research team in Israel found that dreaming of <a href="https://doi.org/10.3389/fpsyg.2018.01812">losing one’s teeth</a> was not particularly linked to symptoms of anxiety but rather associated to teeth clenching during sleep or dental discomfort upon waking.</p>
<p>When we sleep, our brain is not completely cut off from the outside world. It continues to perceive external stimuli, such as sounds or smells, or internal body sensations. That means that other themes, such as not being able to find a toilet or being naked in a public space, could actually be spurred by the need to urinate during the night or by wearing loose pyjamas in bed.</p>
<p>Some physical phenomena specific to REM sleep, the stage of sleep when we dream the most, could also be at play. In REM sleep, our muscles are paralyzed, which could provoke dreams of having heavy legs or being paralyzed in bed.</p>
<p>Similarly, some authors have proposed that dreams of <a href="https://doi.org/10.1176/ajp.134.12.1335">falling or flying are caused by our vestibular system</a>, which contributes to balance and can reactivate spontaneously during REM sleep. Of course, these sensations are not sufficient to explain the recurrence of these dreams in some people and their sudden occurrence in times of stress, but they probably play a significant role in the construction of our most typical dreams.</p>
<h2>Breaking the cycle</h2>
<p>People who experience a recurring nightmare have in some ways become stuck in a particular way of responding to the dream scenario and anticipating it. Therapies have been developed to try to resolve this recurrence and break the vicious cycle of nightmares.</p>
<p>One technique is to visualize the nightmare while awake and then rewrite it, that is, to modify the narrative by <a href="https://doi.org/10.1037/drm0000031">changing one aspect, for example, the end of the dream</a> to something more positive. <a href="https://www.academia.edu/6707271/Lucid_Dreaming_as_a_Treatment_for_Recurrent_Nightmares">Lucid dreaming</a> may also be a solution.</p>
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À lire aussi :
<a href="https://theconversation.com/the-ability-to-control-dreams-may-help-us-unravel-the-mystery-of-consciousness-52394">The ability to control dreams may help us unravel the mystery of consciousness</a>
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<p>In lucid dreams we become aware that we are dreaming and can sometimes influence the content of the dream. Becoming lucid in a recurring dream might allow us to think or react differently to the dream and thereby alter the repetitive nature of it.</p>
<p>However, not all recurring dreams are bad in themselves. They can even be helpful insofar as they are informing us about our personal conflicts. Paying attention to the repetitive elements of dreams could be a way to better understand and resolve our greatest desires and torments.</p><img src="https://counter.theconversation.com/content/166006/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Claudia Picard-Deland has received funding from the Natural Sciences and Engineering Research Council of Canada. </span></em></p><p class="fine-print"><em><span>Tore Nielsen has received funding from the Natural Sciences and Engineering Research Council of Canada. </span></em></p>Dreams help us regulate our emotions and adapt to stressful events. Repetitive content may represent an unsuccessful attempt to integrate difficult experiences.Claudia Picard-Deland, Candidate au doctorat en neurosciences, Université de MontréalTore Nielsen, Professor of Psychiatry, Université de MontréalLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1582372021-04-01T09:42:41Z2021-04-01T09:42:41ZSleeping octopuses might experience fleeting dreams – new study<figure><img src="https://images.theconversation.com/files/392813/original/file-20210331-15-1rvmuh7.jpg?ixlib=rb-1.1.0&rect=54%2C60%2C3886%2C2781&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Octopuses might be able to dream.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-view-common-octopus-vulgaris-1340447465">Shutterstock/Henner Damke</a></span></figcaption></figure><p>A couple of years ago an octopus named Heidi was filmed <a href="https://www.youtube.com/watch?v=0vKCLJZbytU">changing colours as she slept</a>. The footage shows her flickering from a ghostly shade of white to yellow and then turning a deep shade of burgundy before morphing into a mottled green pattern. </p>
<p>The video went viral. Millions were instantly mesmerised by Heidi in her slumber, particularly because the narrator speculates that she’s having a vivid dream – dreaming that she’s hunting and eating a crab, like a snoozing dog chasing “dream rabbits”.</p>
<p>Was Heidi really hunting “dream crabs”? Or was she simply experiencing a muscle twitch that controls her colour-changing skin cells? The video footage is only one piece of the puzzle. We need to know more about an octopus’s sleep patterns to understand what was causing Heidi’s colourful slumber.</p>
<p>Now, a second piece of the puzzle has been revealed. <a href="https://doi.org/10.1016/j.isci.2021.102223">New research</a> has found that these colour-changing patterns in snoozing octopuses are characteristic of two alternating sleep states – a quiet sleep state and an active sleep state. </p>
<h2>Sleeping with the octopuses</h2>
<p>During quiet sleep, octopuses are motionless; their skin is pale and their eyes are narrowed to tightly shut slits. Active sleep is strikingly different – characterised by changes in skin colour and texture as well as flicker movements of the eye, contracting suckers on the arms and muscle twitches on the body.</p>
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<img alt="An octopus in active sleep." src="https://images.theconversation.com/files/392812/original/file-20210331-15-1g2wmo1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/392812/original/file-20210331-15-1g2wmo1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=903&fit=crop&dpr=1 600w, https://images.theconversation.com/files/392812/original/file-20210331-15-1g2wmo1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=903&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/392812/original/file-20210331-15-1g2wmo1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=903&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/392812/original/file-20210331-15-1g2wmo1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1135&fit=crop&dpr=1 754w, https://images.theconversation.com/files/392812/original/file-20210331-15-1g2wmo1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1135&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/392812/original/file-20210331-15-1g2wmo1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1135&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">An octopus in active sleep.</span>
<span class="attribution"><a class="source" href="https://media.eurekalert.org/multimedia_prod/pub/media/259549.jpg">Sylvia L. S. Madeiros</a></span>
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<p>Octopus neuroscientist and leader of the study Sylvia Medeiros caught four wild octopuses, <em>Octopus insularis</em>, in the tropical waters of northern Brazil. She transported them to her lab at the Federal University of Rio Grande do Norte in Natal. There, she watched them snooze. </p>
<p>While sleeping, the octopuses mostly remained in quiet sleep but transitioned into brief bursts of active sleep. Active sleep states typically occurred after a long period of quiet sleep – generally longer than six minutes – and the two sleep states would repeat in a cyclical pattern at 30 to 40 minute intervals.</p>
<p>To confirm the activity states were really sleep, Medeiros and colleagues measured the snoozing octopuses’ arousal thresholds using different stimulation tests. For instance, they presented them with a live crab moving on a video screen or they thumped the aquarium wall with a rubber hammer to create vibrations in the water. The results of these tests suggested the octopuses were indeed sleeping, showing little to no response compared to when they were in an alert state.</p>
<h2>Animal sleep</h2>
<p>According to <a href="https://profiles.stanford.edu/philippe-mourrain">neurobiologist Philippe Mourrain</a> at Stanford University, there has been no evidence of a single species that does not sleep. But until recently, it was thought only mammals and birds show distinct sleep states. </p>
<p>Increasing evidence has demonstrated that animals other than birds and mammals, such as <a href="https://science.sciencemag.org/content/352/6285/590">reptiles</a>, <a href="https://www.nature.com/articles/s41586-019-1336-7">fish</a>, <a href="https://jeb.biologists.org/content/222/1/jeb174862">cuttlefish</a> – the rounder cousin of the octopus – and now <a href="https://doi.org/10.1016/j.isci.2021.102223">octopuses</a> show distinct sleep states. Importantly, these states are similar to what we see in humans.</p>
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<figcaption><span class="caption">Heidi the octopus sleeping.</span></figcaption>
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<p>In humans, rapid eye movement (REM) sleep features the eyes moving rapidly, the heart rate increasing and breathing becoming irregular. Non-REM sleep is characterised by deeper sleep and less dreaming.</p>
<p>Evidence of similar sleep patterns in distantly related animals might offer clues about the origins of sleep, which could help us better understand its biological function – a widely debated topic among neuroscientists. </p>
<p>In mammals, one popular theory of why sleep evolved, particularly REM sleep, is it <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6491889/">helps them control</a> their body temperature. Another popular theory is that it plays a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3768102/">role in memory retention</a> and is a result of high intelligence and brain activity. Finding similar patterns of REM-like sleep in animals that aren’t warm-blooded like reptiles, fish and cephalopods, casts doubt on the first theory, as these animals do not internally control their body temperature.</p>
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<strong>
Read more:
<a href="https://theconversation.com/clever-cuttlefish-show-advanced-self-control-like-chimps-and-crows-155795">Clever cuttlefish show advanced self-control, like chimps and crows</a>
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<p>Despite the similarities between the sleep states of octopuses and vertebrates, including humans, it’s unlikely their sleep patterns were established in a common ancestor. Octopuses and their <a href="https://www.britannica.com/animal/cephalopod">cephalopod</a> cousins split from the vertebrate lineage more than 550 million years ago. They shared a common ancestor that resembled a flatworm with a very simple nervous system. </p>
<p>It’s more likely that these similar sleep patterns evolved independently in these two animal groups, through a process called convergent evolution – where animals evolve similar traits in response to similar pressures in their environment. The question remains, however, what drove the octopus to exhibit distinct sleep states?</p>
<h2>Dream a little dream</h2>
<p>In humans, vivid dreaming occurs during REM sleep. The features exhibited by octopuses during their active sleep states suggests these large-brained molluscs might be experiencing a similar phenomenon to dreaming. But unlike REM sleep in humans, active sleep in octopuses is short, ranging from seconds to one minute. </p>
<p>So, if an octopus is dreaming, it’s unlikely they would experience elaborate and complex plots as we do. Rather, an octopus dream would be fleeting like a <a href="https://www.bustle.com/articles/194546-how-to-use-boomerang-in-instagram-stories-with-the-new-update">Boomerang story</a> on Instagram or a GIF.</p>
<p>According to a <a href="https://doi.org/10.1016/j.cub.2010.10.045">study at Harvard Medical School</a>, dreaming in humans promotes learning because it allows the brain to make important connections between new information and past experiences. Could octopuses dream to better remember what they’ve learned?</p>
<p>It’s a tempting idea – we know that <a href="https://onlinelibrary.wiley.com/doi/10.1111/brv.12651">octopuses are sophisticated learners</a>, so perhaps dreaming helps them optimise their learning abilities. At this stage, however, it is just speculation. We cannot confirm whether octopuses dream, because they can’t verbally report their dreams.</p>
<p>But nothing is impossible in science. New techniques are helping neuroscientists pinpoint hot spots in the human brain that fire up when we dream. By monitoring the brain waves of sleeping volunteers researchers can help identify the signature of a dreaming brain. Perhaps such techniques could be adapted to monitor the brain of a snoozing octopus. It’s always important to dream big.</p><img src="https://counter.theconversation.com/content/158237/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alexandra Schnell receives funding from the Royal Society. </span></em></p>Colour-changing patterns in snoozing octopuses are characteristic of two alternating sleep states.Alexandra Schnell, Research Fellow in Behavioural Ecology, Darwin College, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1418052020-07-01T14:19:49Z2020-07-01T14:19:49ZPasha 70: Why have I been having weird dreams during the pandemic?<figure><img src="https://images.theconversation.com/files/345001/original/file-20200701-159815-pn76w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">shutterstock</span> </figcaption></figure><p>Sleep is incredibly important for the body and mind. When we sleep our immune system makes antibodies, which help fight off pathogens. That’s obviously vital during a health crisis. But many people have been having disrupted sleep and weird dreams in recent times. </p>
<p>In today’s episode of Pasha, Dale Rae, Director of Sleep Science and a senior researcher at the faculty of Health Sciences at the University of Cape Town, discusses why it’s so necessary to sleep well and why the coronavirus is upsetting some people’s rest. </p>
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<p><strong>Photo:</strong>
“Nightmare concept showing a boy on bed facing giant monster in the dark land” By Tithi Luadthong <a href="https://www.shutterstock.com/image-illustration/nightmare-concept-showing-boy-on-bed-1486924805">Shutterstock</a></p>
<p><strong>Music</strong>
“Happy African Village” by John Bartmann, found on <a href="http://freemusicarchive.org/music/John_Bartmann/Public_Domain_Soundtrack_Music_Album_One/happy-african-village">FreeMusicArchive.org</a> licensed under <a href="https://creativecommons.org/publicdomain/zero/1.0/">CC0 1</a>.</p>
<p>“Nobody Sleep” by Paolo Pavan found on <a href="https://freemusicarchive.org/music/Paolo_Pavan/The_Swing_of_Things_1107/Nobody_Sleep">Free Music Archive</a> licensed under <a href="http://creativecommons.org/licenses/by-nc-sa/4.0/">Attribution-NonCommercial-ShareAlike License.</a></p><img src="https://counter.theconversation.com/content/141805/count.gif" alt="The Conversation" width="1" height="1" />
Why is the coronavirus affecting my sleep and dreams?Ozayr Patel, Digital EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1385622020-05-29T00:30:06Z2020-05-29T00:30:06ZJourney to the land of lockdown dreams<figure><img src="https://images.theconversation.com/files/335841/original/file-20200518-83384-a0n5eh.jpg?ixlib=rb-1.1.0&rect=0%2C9%2C1597%2C926&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Still from the film _Dreams_ by Japanese director Akira Kurosawa.</span> <span class="attribution"><span class="source">Warner Bros.</span></span></figcaption></figure><p>As the Covid-19 crisis has unfolded, <a href="https://www.statista.com/chart/21240/enforced-covid-19-lockdowns-by-people-affected-per-country/">billions of people in the world</a> have learned just what the word “lockdown” means. As the days stretched into weeks and even months, sleep was one of the rare escapes from confinement – but maybe not even then. Ask around and you will probably find that others in your circle of friends and family feel the same way: while locked down, our dreams can seem more intense, and even more troubling. But why should this be? </p>
<p>Throughout our lives, sleep provides the brain with crucial time needed to rebuild, repair, and prepare for the next day. Hippocrates himself thought that a good night’s sleep was key to good health, along with a healthy diet, exercise and a fulfilling sex life. Our current knowledge substantiates this: sleep plays a role in many major physiological processes, including eliminating waste, boosting immunity, consolidating memory and even maintaining positive mood. A good night’s sleep really does wonders.</p>
<p>Yet our obligations – our pastimes, even – are often detrimental to our sleep. Those who must get up early each day to drive an hour to work frequently miss out on some sleep. Massive amounts of screen time lead to chronic sleep restriction, with longer-term consequences, including raising rates of obesity, diabetes risk and high blood pressure. Even a small daily sleep deficit affects our concentration and attention, and this deficit is only partially offset by sleeping more over the weekend.</p>
<h2>Longer nights, deeper sleep</h2>
<p>The residents of France emerged from the country’s lockdown on May 11, many having spent 55 straight days inside. They emerged to find a city streets strangely quiet, as if in a dream. Under lockdown, many had been able to savour a pleasure usually reserved for weekends or retirement: an extra hour of sleep. Those able to work from home no longer have a daily commute, and could rest a little longer. Nights in the city were also quieter, with fewer cars and motorbikes to disturb the silence – in the morning, you can even hear birdsong in the heart of Paris. And the less interrupted our sleep is, the better we remember of our dreams.</p>
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<p>The extra hour of morning sleep we have during lockdown is chiefly rapid eye movement (REM) sleep, where the bulk of dreaming takes place. The longest episodes of REM sleep occur at the end of the night, and can last between 30 and 60 minutes. This means people living under lockdown dream more, as they might when on holiday, and their dreams are longer, <a href="https://presse.inserm.fr/en/why-does-the-brain-remember-dreams/11156/">as was shown recently by Perrine Ruby</a>, a research fellow at the Lyon Neuroscience Research Centre.</p>
<p>But is there anything unusual about these dreams?</p>
<h2>The stuff our dreams are made of</h2>
<p>Outside of lockdown, what are our REM-state dreams like? Large surveys of dreams show that the content of our night-time adventures is fairly ordinary, visual and auditory. Dreams are filled with emotions, but they are more often negative (fear, anger, sadness) than positive. Although we frequently have human interactions, they’re only rarely of a sexual nature. The content of our dreams is largely sourced from our daily lives: we see our loved ones and colleagues, move through familiar settings, go about our work and rehash our day-to-day worries.</p>
<p>Ordinary events from the previous day or two feature heavily, but in a troubled and somewhat dramatized form. The majority of our dreams follow this continuity between the dream and the real world, although we sometimes dream of worlds we’ve never seen and actions we’ve never taken. Who hasn’t experienced the thrill of flying in dreams? These eccentricities are rare, yet they make a lasting impression and lend the word “dream” its extraordinary connotation.</p>
<p>According to Freud, dreams in lockdown should feature the things we lack. Deprived our of freedom of movement and our loved ones, we might dream of open spaces, social events or the kinds of food we can no longer eat. Research has shown that this may not be the case, however. For example, in a 1970s study, California researcher Bill Dement restricted subjects’ water intake for 48 hours to see if they would start <a href="https://www.ncbi.nlm.nih.gov/pubmed/13563767">dreaming of fountains</a>. They did not.</p>
<p>So, what do we dream of in lockdown?</p>
<h2>What we dream of in lockdown</h2>
<p>It’s important to note up front that we are in the realms of anecdote and clinical experience rather than hard science. For that, we will have to wait for the results of properly regulated studies currently underway.</p>
<p>As can be expected, the content of dreams in lockdown varies. Recent daily life and those close to us have always been an intrinsic part of our dreams, and while dreams in lockdown sometimes feature idyllic countryside escapes, the threat of the virus has invaded our days (and, for doctors, our work in the hospital) and so has also invaded our dreamscapes.</p>
<p>Over the course of the lockdown, the masked faces and blue scrubs of hospital staff have started to appear in our patients’ dreams. Many people – and by no means just those experiencing the most stress – wake up suddenly at night feeling as if they’re choking, have a fever, or have barely escaped some catastrophe. Bad dreams are common in stressful situations, and lend credibility to a recent theory that one of the purposes of dreams is to virtually simulate threats so as to be able to <a href="https://www.ncbi.nlm.nih.gov/pubmed/18325788">better face them during the day</a>.</p>
<p>Almost all medical students at the Sorbonne University dream of failing their competitive exams the day before. In their dreams, they show up late, are suddenly struck with appendicitis, can’t find their way to the exam room, can’t understand the questions, or don’t know the answers. Yet we have demonstrated that the <a href="https://www.ncbi.nlm.nih.gov/pubmed/25108280">more they fail in dreams, the better they perform on the exam</a>. It is if, after such a nightmare, students were less stressed under real conditions, or were able to anticipate, like chess players, the twists fate might have in store.</p>
<p>Dreams of difficulties and failure abound in all professions: before an important stage debut, actors dream of forgetting their lines; the day before the Olympics, athletes dream of losing their running shoes; taxi drivers find themselves on unknown streets, or far from destinations.</p>
<p>And when a virus threatens humanity, we dream of the virus. In this way, too, we are fighting it.</p><img src="https://counter.theconversation.com/content/138562/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Isabelle Arnulf received funding from Plan National Maladies Rares, Fondation Kleine-Levin syndrome, Académie des Sciences, IHU@ICM, Société Française de Médecine et de Recherche sur le Sommeil, FUI Banque Publique France, and UCB Pharma.</span></em></p>Dreams that are more vivid, more frequent and more striking… Lockdown seems to trouble our nights as well as our days, and there’s reason to believe that’s not just a figment of our imagination.Isabelle Arnulf, Neurologue, professeur de médecine, Institut du Cerveau et de la Moelle épinière - U1127, InsermLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1356092020-04-14T14:21:15Z2020-04-14T14:21:15ZWhy do we dream?<figure><img src="https://images.theconversation.com/files/326828/original/file-20200409-152855-1ye7wfe.jpg?ixlib=rb-1.1.0&rect=26%2C37%2C3567%2C2576&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/lucid-dreaming-series-background-design-human-266440211">agsandrew/Shutterstock</a></span></figcaption></figure><p>Although science knows <a href="https://theconversation.com/what-is-going-on-in-your-brain-when-you-sleep-39723">what dreams are</a>, it is <a href="https://theconversation.com/was-freud-right-about-dreams-after-all-heres-the-research-that-helps-explain-it-60884">still not known exactly why we dream</a>, although plenty of theories exist. </p>
<iframe id="noa-web-audio-player" style="border: none" src="https://embed-player.newsoveraudio.com/v4?key=x84olp&id=https://theconversation.com/why-do-we-dream-135609&bgColor=F5F5F5&color=d8352a&playColor=d8352a" width="100%" height="110px"></iframe>
<p>Dreams are patterns of sensory information that occur when the brain is in a resting state – as in asleep. It is generally assumed that dreams only occur during rapid eye movement (REM) sleep – this is when the brain appears to be in an active state but the individual is asleep and in a state of paralysis. But <a href="https://www.nature.com/articles/srep30932">studies</a> have shown that they can also happen outside of REM. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/books/NBK11121/">Research</a> from sleep studies, for example, shows that REM-related dreams tend to be more <a href="https://sleepcouncil.org.uk/advice-support/sleep-hub/sleep-disorders/vivid-dreams/">fantastical, more colourful and vivid</a> whereas non-REM dreams are more concrete and usually characterised in black and white. <a href="https://www.nature.com/articles/nn.4545">Recent studies</a> <a href="https://books.google.co.uk/books?hl=en&lr=&id=b0aIDwAAQBAJ&oi=fnd&pg=PR11&dq=the+neuroscience+of+sleep+and+dreams&ots=qbODZ3adQl&sig=TPNT54zZyOR3OOJathElv9d3W4M&redir_esc=y#v=onepage&q=the%20neuroscience%20of%20sleep%20and%20dreams&f=false">on dreaming</a> show that during a dream (and in particular a REM-related dream) the emotional centre of the brain is highly active whereas the logical rational centre of the brain is slowed. This can help explain why these dreams are more emotive and surreal. </p>
<p>Evolutionary theory suggests <a href="https://psycnet.apa.org/record/2015-23047-005">the purpose of dreams</a> is to learn, in a safe way, how to deal with challenging or threatening situations. Whereas the “memory consolidation” theory suggests that dreams are a byproduct of reorganising memory in response to what has been learned throughout the day. </p>
<p>Both theories have at least one thing in common – during times of stress and anxiety we either dream more or remember our dreams more often, as a way of coping with challenging circumstances and new information.
This is also in line with another theory of dreaming – <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3330663/">the mood regulatory function of dreams theory</a>, where the function of dreams is to problem-solve emotional issues.</p>
<h2>Anxiety and stress dreams</h2>
<p>While there is no evidence that we dream more when we are stressed, <a href="https://www.researchgate.net/profile/Michael_Schredl/publication/47541043_Nightmare_frequency_in_patients_with_primary_insomnia/links/5687b01b08ae051f9af57f0a/Nightmare-frequency-in-patients-with-primary-insomnia.pdf">research shows</a> we are more likely to remember our dreams because our sleep is poorer and we tend to wake in the night more frequently. </p>
<p><a href="https://www.sciencedirect.com/science/article/abs/pii/S1389945715009053">Studies show</a> the dreams of people with insomnia (a disorder largely characterised by stress) contain more negative emotion and are more focused on the self, in a negative light. Also, the dreams of people with insomnia tend to focus on current life stressors, anxieties and can leave an individual with a low mood the following day. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/326138/original/file-20200407-60103-107m9tc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/326138/original/file-20200407-60103-107m9tc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/326138/original/file-20200407-60103-107m9tc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/326138/original/file-20200407-60103-107m9tc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/326138/original/file-20200407-60103-107m9tc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/326138/original/file-20200407-60103-107m9tc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/326138/original/file-20200407-60103-107m9tc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">‘And then I was sitting on top of a palm tree in a white plastic chair.’</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/contemporary-art-collage-vacation-summer-mood-1461477758">Evgeniya Porechenskaya/Shutterstock</a></span>
</figcaption>
</figure>
<p>Outside of insomnia, <a href="https://www.amazon.co.uk/Twenty-four-Hour-Mind-Dreaming-Emotional/dp/0199896283">research has found</a> that people who are depressed, while going through a divorce, appear to dream differently compared to those who are not depressed. They rate their dreams as more unpleasant. Interestingly though the study found that those depressed volunteers who dreamt of their ex-spouse were more likely to have recovered from their depression a year later compared to those that did not dream of the ex-spouse. Participants whose dreams changed over time, to become less angry and more pragmatic, also showed the greatest improvements. The question is why?</p>
<p>Although our senses are dampened during sleep (with vision being completely absent), strong sensory information, such as an alarm, will be registered and in some cases incorporated into the dream itself. We also know that during times of stress we are more vigilant to threat (on cognitive, emotional and behavioural levels), so it stands to reason that we are more likely to incorporate internal and external signals into our dreams, as a way to manage them. And this may account for these changes in our dreams, when we are anxious, depressed or sleeping badly. </p>
<h2>How to sleep better</h2>
<p>The current thinking is stress reduction before bed and good sleep management – such as keeping a consistent sleep routine, using the bedroom only for sleep, making sure the bedroom is cool, dark, quiet and free from anything arousing – will reduce awakenings at night and so the frequency of stress-related negative dreams. </p>
<p>That said, using a technique called <a href="https://theconversation.com/could-we-one-day-heal-the-mind-by-taking-control-of-our-dreams-60886">Imagery Rehearsal Therapy</a> (IRT), mainly used for treating nightmares in people with post-traumatic stress disorder, it appears stress and anxiety associated with nightmares and bad dreams as well as the frequency of bad dreams can be reduced. This is achieved by re-imagining the ending of the dream or the context of the dream, making it less threatening. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/326147/original/file-20200407-66040-pb7hkq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/326147/original/file-20200407-66040-pb7hkq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/326147/original/file-20200407-66040-pb7hkq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/326147/original/file-20200407-66040-pb7hkq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/326147/original/file-20200407-66040-pb7hkq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/326147/original/file-20200407-66040-pb7hkq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/326147/original/file-20200407-66040-pb7hkq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The night I became a pink unicorn.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/contemporary-art-collage-lady-vintage-watermelon-1461477755">Evgeniya Porechenskaya/Shutterstock</a></span>
</figcaption>
</figure>
<p>There is also <a href="https://www.tandfonline.com/doi/abs/10.1080/15402000902762360%208.">evidence</a> that IRT is effective for <a href="https://pdfs.semanticscholar.org/df5d/92ed9f1830dea20a46c763bbc92e4aa911ff.pdf">reducing nightmares in children</a>. Although IRT is thought to be successful by giving the dreamer a sense of control over the dream, this hasn’t been well studied in people who are stressed or anxious. </p>
<p>That said, <a href="https://www.tandfonline.com/doi/abs/10.1080/15402002.2020.1739688">a recent study</a> showed that teaching people with insomnia to be aware while they were dreaming and <a href="https://theconversation.com/im-a-lucid-dream-researcher-heres-how-to-train-your-brain-to-do-it-118901">to control the dream</a>, as it occurs – known as <a href="https://www.theatlantic.com/health/archive/2014/04/the-ways-to-control-dreaming/360032/">lucid dreaming training</a> – not only reduced their insomnia symptoms but also reduced their symptoms of anxiety and depression. Perhaps then the key is to manage the dreams as opposed to trying to manage the stress – especially in uncertain times.</p><img src="https://counter.theconversation.com/content/135609/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Ellis is director of Sleep Research and Consulting Limited. He has received funding from Health Education England North East, Public Health England, Calms, Irish Rugby Football Union, NIHR, ESRC, Wellcome Trust, Sleep Council, UCB Pharma, NHS Education Scotland, NHS Wales. He has consulted to UCB Pharma, Eisai, Sanofi Aventis, Vermillion Press, Unmind and Third City.</span></em></p>During times of stress and anxiety we either dream more or remember our dreams more often, as a way of coping with challenging circumstances and new information.Jason Ellis, Professor of Sleep Science, Northumbria University, NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1242352019-10-11T13:03:57Z2019-10-11T13:03:57ZBlue light isn’t the main source of eye fatigue and sleep loss – it’s your computer<figure><img src="https://images.theconversation.com/files/296496/original/file-20191010-188807-u4v7v7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">While blue light has been blamed for sleep loss, it's not the only bad light.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-front-computer-screen-dark-night-11514280?src=BLyrJPAqyFp0jEYxevcAxA-1-6">Chaoss/Shuttterstock.com</a></span></figcaption></figure><p>Blue light has gotten a bad rap, <a href="https://www.forbes.com/sites/fionamcmillan/2018/08/11/how-blue-light-damages-cells-in-your-eyes/">getting blamed for loss of sleep and eye damage</a>. Personal electronic devices <a href="https://doi.org/10.3389/fpubh.2015.00233">emit more blue light than any other color</a>. Blue light has a short wavelength, which means that it is high-energy and can damage the delicate tissues of the eye. It can also pass through the eye to the retina, the collection of neurons that converts light into the signals that are the foundation of sight.</p>
<p>Laboratory studies have shown that prolonged exposure to high-intensity blue light <a href="https://www.sciencedirect.com/science/article/pii/S1011134409000025?via%3Dihub">damages retinal cells</a> in mice. But, epidemiological <a href="https://doi.org/%2010.1016/j.ophtha.2004.10.047">studies on real people</a> tell a different story. </p>
<p>As an <a href="https://scholar.google.com/citations?user=thGgi2UAAAAJ&hl=en">assistant professor at The Ohio State University</a> College of Optometry, I teach and conduct vision research, including work with retinal eye cells. I also see patients in the college’s teaching clinics. Often, my patients want to know how they can keep their eyes healthy despite looking at a computer screen all day. They often ask about “blue-blocking” spectacle lenses that they see advertised on the internet. </p>
<p>But when it comes to protecting your vision and keeping your eyes healthy, blue light isn’t your biggest concern.</p>
<h2>Built-in protection</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/296516/original/file-20191010-188814-2yoh66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/296516/original/file-20191010-188814-2yoh66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/296516/original/file-20191010-188814-2yoh66.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/296516/original/file-20191010-188814-2yoh66.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/296516/original/file-20191010-188814-2yoh66.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/296516/original/file-20191010-188814-2yoh66.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/296516/original/file-20191010-188814-2yoh66.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Sunlight has more blue light than your computer.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-portrait-beautiful-african-american-woman-387806866?src=W0qyo74vYxTxbsOSZ4sWfw-1-13">miamgesphotography/Shutterstock.com</a></span>
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<p>One way to think about blue light and potential retinal damage is to consider the Sun. <a href="https://www.intechopen.com/books/biofuels-economy-environment-and-sustainability/the-possibility-of-future-biofuels-production-using-waste-carbon-dioxide-and-solar-energy">Sunlight</a> is mostly blue light. On a sunny afternoon, it’s nearly <a href="https://doi.org/10.7554/eLife.15392">100,000 times brighter</a> than your computer screen. Yet, few human studies have found <a href="https://jamanetwork.com/journals/jamaophthalmology/fullarticle/268111">any link</a> between sunlight exposure and the development of age-related macular degeneration, a retinal disease that leads to loss of central vision.</p>
<p>If being outside on a sunny afternoon likely doesn’t damage the human retina, then neither can your dim-by-comparison tablet. A theoretical study recently <a href="https://doi.org/10.1038/eye.2015.261">reached the same conclusion</a>.</p>
<p>So, why the disconnect between blue light’s effects on rodent eyes and human eyes?</p>
<p>Human eyes are different than rodent eyes. We have protective elements, such as <a href="https://doi.org/10.1038/sj.eye.6702780">macular pigments</a> and the natural blue-blocking ability of the <a href="https://doi.org/10.1113/jphysiol.1988.sp016935">crystalline lens</a>. These structures absorb blue light before it reaches the delicate retina. </p>
<p>That doesn’t mean you should throw away those sunglasses; they provide benefits beyond protecting your eyes from the Sun’s blue light. For example, wearing sunglasses <a href="https://doi.org/%2010.1074/jbc.M114.554410">slows down the development of cataracts</a>, which cloud vision.</p>
<h2>Feeling the blues</h2>
<p>Just because blue light isn’t harming your retina doesn’t mean your electronic devices are harmless, or that blue light doesn’t affect your eyes. Because of its wavelength, blue light does <a href="https://doi.org/10.1523/JNEUROSCI.21-16-06405.2001">disrupt healthy sleep physiology</a>. <a href="https://doi.org/10.1126/science.1067262">Blue-light-sensitive</a> cells, known as known as intrinsically photosensitive retinal ganglion cells, or ipRGCs, play a key role here, because they tell the brain’s master clock how light it is in the environment. That means, when you look at a brightly lit screen, these cells help set your internal clock for daytime-level alertness. </p>
<p>But these cells are sensitive to colors beyond blue because they also receive input from <a href="https://www.physiology.org/doi/full/10.1152/physrev.00013.2010?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed">other retinal neurons</a> that are sensitive to the entire color spectrum. </p>
<p>Therefore, eliminating blue light alone doesn’t cut it when it comes to improving sleep; you need to dim all colors.</p>
<p>As for your tired eyes after a long day spent staring at your computer – another common complaint I hear from my patients – blue light isn’t solely to blame for that, either. A recent study demonstrated that cutting blue light alone <a href="https://doi.org/10.1097/OPX.0000000000001318">did not improve</a> people’s reported comfort after a long computer session any more than simply dimming the screen. </p>
<h2>Does blocking the blue make sense?</h2>
<p>Many patients want to know if they should buy certain products they have seen advertised to block out blue light. Based on research, the short answer is “no.” </p>
<p>First, the truth is that any bright light too close to bedtime interferes with sleep.</p>
<p><a href="https://doi.org/10.1073/pnas.1418490112">Mounting evidence</a> suggests that, compared to reading a paperback, screen time before bed increases the time it takes to fall asleep. It also robs you of restorative rapid-eye-movement sleep, dulls focus and diminishes brain activity the next day. Holding your phone close to your eyes with the lights on likely <a href="https://doi.org/10.1038/srep11325">exacerbates the problem</a>.</p>
<p>Second, the products that my patients ask about do not block out much blue light. The leading blue-blocking anti-reflective coating, for example, <a href="https://doi.org/10.1097/OPX.0000000000001393">blocks only about 15%</a> of the blue light that screens emit.</p>
<p>You could get the same reduction just by holding your phone another inch from your face. Try it now and see if you notice a difference. No? Then it shouldn’t surprise you that a recent meta-analysis concluded that blue-blocking lenses and coatings have <a href="https://doi.org/10.1111/opo.12406">no significant effect</a> on sleep quality, comfort at the computer, or retinal health.</p>
<h2>What really works</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/296512/original/file-20191010-188823-19v26go.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/296512/original/file-20191010-188823-19v26go.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/296512/original/file-20191010-188823-19v26go.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/296512/original/file-20191010-188823-19v26go.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/296512/original/file-20191010-188823-19v26go.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/296512/original/file-20191010-188823-19v26go.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/296512/original/file-20191010-188823-19v26go.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Computers cause eye strain because people don’t blink as often when staring at a screen.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-woman-taking-off-glasses-tired-1075401764?src=kSqTmRfglJpQ53eQzQoDGQ-1-18">fizkes/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>There are ways to make your screen viewing more comfortable and more conducive to sleep. </p>
<p>First, turn off your electronic devices before bed. The <a href="https://www.aap.org/en-us/about-the-aap/aap-press-room/Pages/American-Academy-of-Pediatrics-Announces-New-Recommendations-for-Childrens-Media-Use.aspx">American Academy of Pediatrics</a> recommends that bedrooms be “screen-free” zones for children, but we should all heed this advice. Outside of the bedroom, when you do look at your screens, lower the brightness. </p>
<p>As for eye strain, ensure that you have the appropriate glasses or contact lens prescription. Only an optometrist or ophthalmologist can give you this information.</p>
<p>You also need to take care of the surface of your eyes. We don’t just look at our computer screens, we stare at them. In fact, our <a href="https://doi.org/10.1007/s00417-003-0786-6">blink rate plummets</a> from about 12 blinks a minute to six. As a result, tears evaporate off the eyes, and they don’t accumulate again until we step away from the screen and start blinking. This causes inflammation on the eye’s surface. That’s why your eyes feel dry and tired after a day spent at the computer. I counsel my patients to take two steps to ensure that their eyes stay moist during long computer sessions.</p>
<p>First, follow the “20-20-20” rule. The <a href="https://www.aoa.org/documents/infographics/SYVM2016Infographics.pdf">American Optometric Association</a> defines this rule as taking a 20-second break every 20 minutes to look at something 20 feet in the distance. This will allow your eyes to blink and relax. There are many apps available to help remind you to follow this rule.</p>
<p>Second, use a lubricating eye drop before extended computer use. This tactic will reinforce the body’s natural tears and keep the eye’s surface hydrated. But, avoid those “get-the-red-out” drops. They contain drugs that cause long-term redness and preservatives that may <a href="https://www.sjeyeassociates.com/the-dangers-of-redness-relief-eye-drops/">damage the outer layers of the eye</a>. I have found that artificial tears labeled “preservative free” often work best.</p>
<p>Based on my research, my advice is don’t believe the hype about blue light and don’t waste your money on products you don’t need. Instead, keep screens out of your bedroom and dim them before bedtime and keep your eyes lubricated. And don’t forget to blink!</p>
<p>[ <em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/124235/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Phillip Yuhas receives funding from the National Institutes of Health and the Ohio Lions Eye Research Foundation. He is a member of the American Optometric Association, the Ohio Optometric Association, the American Academy of Optometry, and the Association for Research in Vision and Ophthalmology. </span></em></p>Blue light has been getting blamed for sleep interruption and eye strain. But the facts are that any bright light interferes with sleep, and computers themselves cause eye strain, an eye doctor says.Phillip Yuhas, Assistant Professor of Optometry, The Ohio State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1211252019-09-04T06:03:30Z2019-09-04T06:03:30ZCurious Kids: why are some people affected by sleep paralysis?<figure><img src="https://images.theconversation.com/files/289562/original/file-20190827-184217-65osi.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4256%2C2803&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sleep paralysis is when you wake up but feel like you can't move. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/asian-boy-sleeping-disorder-bad-dream-120060874">Shutterstock</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em>If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au.</em> </p>
<hr>
<blockquote>
<p><strong>Why are some people affected by sleep paralysis? – Tess, age 13.</strong></p>
</blockquote>
<hr>
<p>Falling asleep is a bit like flicking off a light switch. One moment we are awake, but then the switch is flicked and we fall asleep. </p>
<p>That’s how it’s supposed to work, anyway. But sometimes, the switch gets a bit “sticky” and the light flickers between being awake and asleep. This is what happens with sleep paralysis – when you wake up but feel like you can’t move. </p>
<p>To answer your question, you’re more likely to experience sleep paralysis if: </p>
<ul>
<li>someone <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/jsr.12282">in your family</a> has it;</li>
<li>you don’t get <a href="https://www.dovepress.com/relationships-between-sleep-paralysis-and-sleep-quality-current-insigh-peer-reviewed-fulltext-article-NSS">enough sleep</a> or you have changed your regular sleep pattern</li>
<li>you are a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4958367/">shift worker</a>;</li>
<li>it seems to be more common when you <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4958367/">sleep on your back</a> (but we don’t know why);</li>
<li>you are <a href="https://www.dovepress.com/relationships-between-sleep-paralysis-and-sleep-quality-current-insigh-peer-reviewed-article-NSS">stressed</a> or taking <a href="https://n.neurology.org/content/52/6/1194.long">certain medicines</a>;</li>
<li>you have a sleep disorder such as <a href="https://www.nature.com/articles/s41582-019-0226-9">narcolepsy</a> (which is where you <a href="https://www.sleephealthfoundation.org.au/pdfs/Narcolepsy.pdf">fall asleep suddenly and uncontrollably</a> when it’s not really sleep time, like in class).</li>
</ul>
<p>Many people experience sleep paralysis at some stage, and it’s usually first noticed in teenagers. It can affect men or women. </p>
<p>Overall, though, there’s still a lot scientists don’t know about sleep paralysis and why some people are more prone to it than others.</p>
<p>Here’s a bit about what we do know. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-where-do-dreams-come-from-105130">Curious Kids: Where do dreams come from?</a>
</strong>
</em>
</p>
<hr>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/290449/original/file-20190902-175696-1gm8sre.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/290449/original/file-20190902-175696-1gm8sre.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/290449/original/file-20190902-175696-1gm8sre.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/290449/original/file-20190902-175696-1gm8sre.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/290449/original/file-20190902-175696-1gm8sre.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/290449/original/file-20190902-175696-1gm8sre.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/290449/original/file-20190902-175696-1gm8sre.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/290449/original/file-20190902-175696-1gm8sre.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sleep paralysis can feel like something is sitting on you and stopping you from moving.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Our brain is half asleep</h2>
<p>In the olden days, some people called sleep paralysis the “<a href="https://en.wikipedia.org/wiki/Night_hag">Night Hag</a>” and said it felt like a spooky witch or demon was sitting on your chest. Now we know it is quite a common sleep problem or what doctors call a <a href="https://www.sleepfoundation.org/articles/sleep-and-parasomnias">parasomnia</a>, caused by a little brain hiccup. And thankfully, it usually doesn’t last very long. </p>
<p>With sleep paralysis, some parts of your brain are awake and still active but other parts are fast asleep. </p>
<p>The sleeping part is the section of the brain that <a href="https://www.jneurosci.org/content/32/29/9785.long">tells the muscles to relax while we sleep</a> so we don’t act out our dreams. Evolution probably gave us that trick because acting out dreams can be harmful to yourself or others (although this trick doesn’t always work and some people do <a href="https://www.mayoclinic.org/diseases-conditions/rem-sleep-behavior-disorder/symptoms-causes/syc-20352920">act out their dreams</a>). </p>
<p>Sleep paralysis can feel pretty strange and scary, at least until you realise what is happening. </p>
<h2>Sleep paralysis often doesn’t need treatment</h2>
<p>If you are unable to move or speak for a few seconds or minutes when falling asleep or waking up, then it is likely that you have what doctors call “<a href="http://sleepeducation.org/sleep-disorders-by-category/parasomnias/sleep-paralysis/overview-facts">isolated recurrent sleep paralysis</a>”. </p>
<p>If you sometimes experience sleep paralysis, here are some things you can try at home:</p>
<ul>
<li>make sure you <a href="https://www.sleepfoundation.org/excessive-sleepiness/support/how-much-sleep-do-we-really-need">get enough sleep</a> </li>
<li>try to reduce stress in your life, especially just before bedtime</li>
<li>try a different sleeping position (especially if you sleep on your back)</li>
</ul>
<p>See your doctor if sleep paralysis continually prevents you from getting a good night’s sleep. </p>
<p>Your doctor may ask about how you’re feeling, your health history and if your family has had sleep problems. They may tell you to go to a specialist sleep doctor who can investigate further. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-what-happens-in-our-bodies-when-we-sleep-94301">Curious Kids: What happens in our bodies when we sleep?</a>
</strong>
</em>
</p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au</em></p><img src="https://counter.theconversation.com/content/121125/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Danny Eckert receives funding from the NHMRC, Cooperative Research Centre funding and industry partnerships. He is affiliated with the Research Committee for the Australasian Sleep Association. </span></em></p>Sleep paralysis – when you wake up but feel like you can’t move – seems to be more common if you sleep on your back. But we don’t know why.Danny Eckert, Director, Adelaide Institute for Sleep Health, Professor, College of Medicine and Public Health, Flinders University, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1202822019-08-12T19:58:43Z2019-08-12T19:58:43ZCurious Kids: why don’t people fall out of bed when they are sleeping?<figure><img src="https://images.theconversation.com/files/284234/original/file-20190716-173329-m1hcrj.jpg?ixlib=rb-1.1.0&rect=351%2C27%2C5655%2C3980&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Even when we are asleep, we can still feel if we are comfortable and our 'sixth sense' is working to let us know where we are in our beds.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/little-african-american-girl-sleeping-bed-610536542?src=xJyUn1n8LZjp3uRJcnpFRA-1-23&studio=1">www.shuttershock.com </a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em>If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au.</em> </p>
<hr>
<blockquote>
<p><strong>How do people know not to fall out of their beds when they are sleeping? – Louisa, age five.</strong></p>
</blockquote>
<hr>
<p>You might think that when we sleep we are completely unconscious and we have no idea what is happening around us. But that isn’t quite true. </p>
<p>When we’re sleeping, our bodies and brains are still working to keep us healthy and happy. We also still have some idea of where we are.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-what-happens-in-our-bodies-when-we-sleep-94301">Curious Kids: What happens in our bodies when we sleep?</a>
</strong>
</em>
</p>
<hr>
<p>Our body knows how it is moving and where it is because of a sense called “<a href="https://en.wikipedia.org/wiki/Proprioception">proprioception</a>”. It’s like a “sixth sense” that helps your body know where it is in the world and where all the parts of your body are in relation to each other. </p>
<p>When we are awake, this sixth sense stops us from walking into things or falling over. </p>
<p>You might think that it would switch off when we’re sleeping. But because our bodies still work while we’re sleeping, our sixth sense is still working too. </p>
<p>Even though we are asleep, we can still feel if we are comfortable and our sixth sense is working to let us know where we are in our beds. This helps us know not to fall out. </p>
<p>But the system doesn’t always work very well when we are young. This is why kids fall out of bed sometimes. </p>
<p>We get better at this as we get older, so older children and adults are less likely to fall out of bed. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/286887/original/file-20190805-36358-92ajcq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/286887/original/file-20190805-36358-92ajcq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=428&fit=crop&dpr=1 600w, https://images.theconversation.com/files/286887/original/file-20190805-36358-92ajcq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=428&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/286887/original/file-20190805-36358-92ajcq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=428&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/286887/original/file-20190805-36358-92ajcq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=538&fit=crop&dpr=1 754w, https://images.theconversation.com/files/286887/original/file-20190805-36358-92ajcq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=538&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/286887/original/file-20190805-36358-92ajcq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=538&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Our bodies and brains are still working when we sleep.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/adorable-little-child-girl-sleeping-bed-415126918?src=cj16E3IwH203imAC9Vm_mw-1-12&studio=1">Shutterstock</a></span>
</figcaption>
</figure>
<h2>The different stages of sleep</h2>
<p>Our sleep isn’t the same the whole night through. It goes through different stages, from light sleep to deep sleep and back again. </p>
<p>One special stage of sleep, where we have our most exciting dreams, is called REM sleep. REM stands for rapid eye movement. That’s when our eyes are moving around to try to see everything that is happening while we are dreaming. </p>
<p>During this stage, our brain sends a message to our body to stop moving to make it less likely we will get up or fall out of bed.</p>
<p>If our body didn’t send this message to our brain, we would act out our dreams!</p>
<h2>Message not recieved</h2>
<p>Some people’s brains don’t send this message and these people do act out their dreams. This is called “rapid eye movement behaviour disorder”. It is very rare.</p>
<p>There are stories of people with this disorder doing things like patting imaginary cats or hurting themselves by trying to jump out of bed while they’re still asleep. Most of them wake up not knowing they did anything unusual until someone tells them. </p>
<p>Sleep is very important to help us grow big and strong. Our bodies and brains are still working while we are asleep to heal any injuries and help keep us happy and healthy. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-where-do-dreams-come-from-105130">Curious Kids: Where do dreams come from?</a>
</strong>
</em>
</p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au</em></p><img src="https://counter.theconversation.com/content/120282/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alex Agostini does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Our body knows how it is moving and where it is because of a sense called proprioception, a ‘sixth sense’ that helps your body know where it is in the world. And it works even while you’re asleep.Alex Agostini, Post doctoral research fellow, University of South AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1174652019-06-06T17:31:11Z2019-06-06T17:31:11ZDoes hitting the snooze button really help you feel better?<figure><img src="https://images.theconversation.com/files/277264/original/file-20190530-69095-1y3yjyz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">How many times do you hit snooze before getting out of bed?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/unrecognisable-male-going-touch-snooze-button-1101503465?src=6QxGaxMA0bscEUOAnUpQrg-1-3">DGLimages</a></span></figcaption></figure><p>To sleep or to snooze? You probably know the answer, but you don’t prefer it.</p>
<p>Most of us probably use the snooze function on our alarm clocks at some point in our lives. Just a few more minutes under the covers, a time to gather our thoughts, right? </p>
<p>While such snoozing might seem harmless, it may not be. For starters, it is important to understand why we are using the snooze button in the first place. For some it’s a habit that started early on. But for many, it can signal a significant problem with sleep. <a href="http://doi.org/10.1111/j.1468-5884.2011.00463.x">Poor sleep has been shown to be associated</a> with a number of health disorders including high blood pressure, memory problems and even weight control.</p>
<p>I’m a <a href="https://scholar.google.com/citations?hl=en&user=P-nOtiwAAAAJ">facial pain specialist</a> and have extensively studied sleep and how it impacts painful conditions. With testing, we discover that many of our chronic pain patients also suffer with various sleep disorders. </p>
<h2>What does normal sleep look like?</h2>
<p>If one is tired when the alarm goes off, is it helpful to use the snooze button? While there are no scientific studies that address this topic specifically, the answer is probably not. Our natural body clock regulates functions through what’s known as <a href="https://doi.org/10.1210/er.2016-1083">circadian rhythms</a> – physical, mental and behavioral changes that follow a daily cycle. </p>
<p>Most adults require approximately seven and a half to eight hours of good sleep per night. This enables us to spend adequate time in the <a href="https://www.elsevier.com/books/principles-and-practice-of-sleep-medicine/kryger/978-1-4160-6645-3">stages of sleep</a> known as nonrapid eye movement sleep (NREM) and rapid eye movement sleep (REM). </p>
<p>[<em>Get the best of The Conversation, every weekend.</em> <a href="https://theconversation.com/us/newsletters/weekly-highlights-61?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=weeklybest">Sign up for our weekly newsletter</a>.]</p>
<p>We tend to cycle from the three stages of NREM into REM sleep four to six times per night. The first portion of the night is mostly NREM deep sleep and the last portion consists of mostly REM sleep. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/277270/original/file-20190530-69075-l2ebbq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/277270/original/file-20190530-69075-l2ebbq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=426&fit=crop&dpr=1 600w, https://images.theconversation.com/files/277270/original/file-20190530-69075-l2ebbq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=426&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/277270/original/file-20190530-69075-l2ebbq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=426&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/277270/original/file-20190530-69075-l2ebbq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=535&fit=crop&dpr=1 754w, https://images.theconversation.com/files/277270/original/file-20190530-69075-l2ebbq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=535&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/277270/original/file-20190530-69075-l2ebbq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=535&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The stages of sleep.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/cycles-sleep-1198377799?src=5rPgRX6MJHQngIzrKZyRRA-1-2">arka38/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Good sleep is important</h2>
<p>Maintaining this well-defined structure is important for good, restful sleep. If this process is disturbed, we tend to awaken still feeling tired in the morning. </p>
<p><a href="https://doi.org/10.1378/chest.14-0970">A number of factors</a> can affect the sleep cycles. For example, if a person is not breathing well during sleep (snoring or sleep apnea), this will disturb the normal sequences and cause the individual to awaken feeling unrestored. Sleep quality can be diminished by the use of electronic devices, tobacco or alcohol in the evening. Even eating too close to bedtime can be problematic. </p>
<p>The use of snooze buttons often starts during the teenage years, when our circadian rhythms are altered somewhat, causing us to want to stay up later and get up later in the morning. Delaying getting out of bed for nine minutes by hitting the snooze is simply not going to give us any more restorative sleep. In fact, it may serve to confuse the brain into starting the process of secreting more neurochemicals that cause sleep to occur, according to some hypotheses. </p>
<p>Bottom line: It’s probably best to set your alarm for a specific time and get up then. If you are consistently tired in the morning, consult with a sleep specialist to find out why.</p><img src="https://counter.theconversation.com/content/117465/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steven Bender does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>You are tired. Would nine more minutes really hurt? Is hitting the snooze button a good idea? Should you just get out of bed? Or is snoozing a sign of a more serious medical issue?Steven Bender, Clinical Assistant Professor of Oral and Maxillofacial Surgery, Texas A&M UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1025272018-10-05T11:44:55Z2018-10-05T11:44:55ZThe best foods to eat for a good night’s sleep<figure><img src="https://images.theconversation.com/files/239145/original/file-20181003-52691-1akb3jw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Sleep has become widely recognised as playing <a href="https://theconversation.com/what-is-going-on-in-your-brain-when-you-sleep-39723">a really important role</a> in our overall health and wellness – alongside diet, stress management and exercise.</p>
<p>Recently, researchers have been learning more about how poor sleep influences our dietary choices, as well as how diet influences sleep quality. <a href="https://theconversation.com/how-a-lack-of-sleep-affects-your-brain-and-personality-66604">Not sleeping for long enough</a> or poor quality sleep are associated with increased food intake, a less healthy diet and <a href="https://www.ncbi.nlm.nih.gov/pubmed/24051052">weight gain</a>. <a href="https://www.ncbi.nlm.nih.gov/pubmed/30151232">Lack of sleep</a> also leads to increased snacking and overeating. And it causes us to want to eat foods <a href="https://www.ncbi.nlm.nih.gov/pubmed/30151232">high in fat and carbohydrates</a> – with increased chemical rewards to the brain when we do eat these foods. </p>
<p>Essentially, poor sleep <a href="https://theconversation.com/does-a-lack-of-sleep-really-make-children-overweight-heres-the-science-74478">drives your body to find high energy foods</a> to keep you awake which makes fighting the cravings for unhealthy foods very difficult to resist. But, on the other hand, when we have slept well our appetite hormones are at a normal level. We don’t crave unhealthy food so much – and we can make better choices about what to eat.</p>
<h2>The science of sleep</h2>
<p>All cultures around the world have traditions about which foods promote sleep. <a href="https://www.ncbi.nlm.nih.gov/pubmed/22652369">Foods</a> such as milk, chamomile, kiwi fruit and tart cherries, have all been said to work wonders for a good night’s sleep. Given how much the food we eat affects us on a day-to-day basis, it is not surprising that our diet plays such a big role in our quality of sleep. What we eat also has a big impact on our organ function, immune system, hormone production and brain function. </p>
<p>A really important hormone that controls our sleep patterns is <a href="https://www.ncbi.nlm.nih.gov/pubmed/30148726">melatonin</a>. Melatonin is produced in the brain and the amount of melatonin you produce and how efficiently our brain uses it is affected by our diet. One of the biggest influence on our melatonin levels appears to be our <a href="https://www.ncbi.nlm.nih.gov/pubmed/25407790">intake of a type of protein</a> called <a href="https://www.ncbi.nlm.nih.gov/pubmed/27934652">tryptophan</a>. Tryptophan is an essential amino acid – the building blocks of proteins. Essential amino acids are a group which our bodies cannot make, it can only be sourced through diet. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/239146/original/file-20181003-52672-bq1te4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/239146/original/file-20181003-52672-bq1te4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/239146/original/file-20181003-52672-bq1te4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/239146/original/file-20181003-52672-bq1te4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/239146/original/file-20181003-52672-bq1te4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/239146/original/file-20181003-52672-bq1te4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/239146/original/file-20181003-52672-bq1te4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Eating and drinking for better sleep is about more than just avoiding caffeine.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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</figure>
<p>Other nutrients that appear to be helpful for sleep include B vitamins and magnesium. This is because they help tryptophan to be <a href="https://www.ncbi.nlm.nih.gov/pubmed/30151232">more available in the body</a>. If your diet is lacking tryptophan, B vitamins or magnesium. It is very likely that your melatonin production and secretion will be affected and your <a href="https://www.ncbi.nlm.nih.gov/pubmed/22652369">sleep quality will be poorer</a>. </p>
<h2>Eat to sleep</h2>
<p>It stands to reason then that following overly restrictive diets or diets that put you at risk of nutrient deficiencies can really affect your sleep. But by increasing your intakes of foods rich in specific nutrients, it may well help to promote better sleep quality and duration. </p>
<p><a href="https://www.bbcgoodfood.com/howto/guide/how-get-good-nights-sleep">Dairy foods</a>, for example, can be great at helping you sleep. Not only is dairy an excellent source of tryptophan, but it also contains magnesium and B vitamins which help to promote the activity and availability of tryptophan. Nuts, like dairy, also contain all the nutrients known to promote increase melatonin production and support its release.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/239147/original/file-20181003-52660-q44ucv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/239147/original/file-20181003-52660-q44ucv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/239147/original/file-20181003-52660-q44ucv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/239147/original/file-20181003-52660-q44ucv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/239147/original/file-20181003-52660-q44ucv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/239147/original/file-20181003-52660-q44ucv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/239147/original/file-20181003-52660-q44ucv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">‘To dreams made of milk’</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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<p><a href="http://time.com/5077404/fish-omega-3-sleep/">Fish is a great source of tryptophan</a> and B vitamins. Fish with bones, such as sardines, will also provide magnesium. Including fish in your diet regularly may help to promote healthy melatonin production when you need it. Pulses, beans and lentils also contain <a href="https://www.myfooddata.com/articles/high-tryptophan-foods.php">high amounts of tryptophan</a> and B vitamins. Adding some tofu or paneer to a vegetable stew or curry can also help to increase your likelihood of having a great night’s sleep. You could also add in some soya – which is another good source of tryptophan – to optimise your sleep potential. </p>
<p>And if you’re still struggling to sleep, it might be that you’d benefit from some meat. Meat of all kinds contains all the essential ingredients for a good night’s sleep. So if you can’t nod off at night, maybe think about adding some lean meat to your diet. </p>
<p>If you find yourself hungry before bed, for the ideal bed time snack, try a glass of semi-skimmed or skimmed milk, a small banana or a few nuts – all of which can really help to improve your sleep and your willpower the next day. It’s also worth pointing out that it takes <a href="http://www.bbc.co.uk/guides/z282p39">around an hour</a> for the tryptophan in foods to reach the brain, so don’t wait until just before bedtime to have your snack. And it’s also advisable to have a balanced diet that includes plenty of foods that are high in tryptophan throughout the day to optimise your chances of a good night’s sleep.</p><img src="https://counter.theconversation.com/content/102527/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sophie Medlin does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A dietician recommends her top foods for a peaceful sleep.Sophie Medlin, Lecturer in Nutrition and Dietetics, King's College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/935342018-06-20T08:26:16Z2018-06-20T08:26:16ZWhat lies behind ghosts, demons and aliens – according to sleep researchers<figure><img src="https://images.theconversation.com/files/223618/original/file-20180618-85845-15vgp4a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Captblack76/Shutterstock.com</span></span></figcaption></figure><p>If you believe in the paranormal you might not be surprised if you hear stories of deceased loved ones appearing during the night, huge explosions heard just as someone is drifting off with no obvious cause, and other peculiar occurrences. But what if you don’t?</p>
<p>My interest in the paranormal started with an impromptu coffee with a colleague, <a href="https://theconversation.com/profiles/christopher-french-168769">Chris French</a>, who researches reports of paranormal experiences. He told me stories of countless people who had recounted such events. These experiences tended to start while lying in bed. Then something unusual would happen – perhaps a demon would appear or the environment would seem strange or there would be a sensed presence. The person having this experience might also report being glued to their mattress, tarmacked into the bed, totally unable to move. </p>
<p>It’s unsurprising that people who experience such things might interpret them as paranormal. But certain phenomena such as <a href="https://global.oup.com/academic/product/sleep-paralysis-9780199313808?q=brian%20sharpless&lang=en&cc=us">sleep paralysis</a> provide an alternative to paranormal explanations for such occurrences. Hence my interest in the subject, as a sleep researcher. </p>
<h2>Sleep paralysis</h2>
<p>When we sleep, we cycle through different stages. We start the night in non-rapid eye movement (NREM) sleep – which gets progressively deeper. We then cycle back until we hit rapid eye movement (REM) sleep. During REM sleep we are most likely to have vivid dreams. At this stage we are also paralysed, perhaps as a safety mechanism to stop us acting out our dreams so that we don’t end up attempting to fly. </p>
<p>But during sleep paralysis, features of REM sleep continue into waking life. Those who experience it will feel awake yet might experience dream-like hallucinations and struggle to move. This experience is pretty common, occurring in around 8% of people (although <a href="https://www.sciencedirect.com/science/article/pii/S1087079211000098?via%3Dihub">estimates vary dramatically</a> depending on who we are asking). It’s even possible to <a href="https://www.ncbi.nlm.nih.gov/pubmed/1621022">induce sleep paralysis</a> in some people, by disrupting their sleep in specific ways.</p>
<p>Certain researchers, French among them, believe that this explains a huge number of paranormal accounts. Information about sleep paralysis is finally seeping into <a href="https://www.huffingtonpost.co.uk/entry/kendall-jenner-sleep-paralysis_us_580a2833e4b0cdea3d86e413">public awareness</a>, but we now need to understand more about this common complaint. </p>
<p>Our preliminary work, which I recount in my new book <a href="https://bloomsbury.com/uk/nodding-off-9781472946188/">Nodding Off: The science of sleep from cradle to grave</a>, hints at possible <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/jsr.12282">genetic and environmental explanations</a> for why some people are more likely than others to experience sleep paralysis. This now needs to be replicated using much larger samples. Reviewing the literature, we have also highlighted a host of other <a href="http://www.smrv-journal.com/article/S1087-0792(17)30112-0/abstract">variables associated with this common experience</a>, including stress, trauma, psychiatric difficulties and physical illnesses. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/223620/original/file-20180618-85854-xl2b58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/223620/original/file-20180618-85854-xl2b58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/223620/original/file-20180618-85854-xl2b58.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/223620/original/file-20180618-85854-xl2b58.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/223620/original/file-20180618-85854-xl2b58.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/223620/original/file-20180618-85854-xl2b58.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/223620/original/file-20180618-85854-xl2b58.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The worst dreams.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/afraid-young-woman-hiding-white-blanket-106535048?src=oHbLZiN9CMU_8X-qIuLZiw-1-23">Creativa Images/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Exploding head syndrome</h2>
<p>Sleep paralysis aside, how else are sleep researchers helping to explain paranormal experiences? People sometimes describe experiencing huge explosions during the night which simply can’t be explained. There is no sign that a shelf has fallen down or a car has backfired. There is no one playing the electric guitar next to their head. </p>
<p>Again, this can be linked to our sleep - this time explained by “<a href="http://www.smrv-journal.com/article/S1087-0792(14)00022-7/abstract">exploding head syndrome</a>”, a term <a href="https://www.sciencedirect.com/science/article/pii/S0140673688925512?via%3Dihub">coined relatively recently</a> by the neurologist JMS Pearce. When we fall asleep, the reticular formation of the brainstem (a part of our brain involved in consciousness) typically starts to inhibit our ability to move, see and hear things. When we experience a “bang” in our sleep this might be because of a <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1468-2982.2007.01522.x">delay in this process</a>. Instead of the reticular formation shutting down the auditory neurons, they might fire at once. </p>
<p>As with sleep paralysis, this phenomenon is also under-researched. For this very reason, in 2017 my colleagues and I joined forces with <a href="http://www.sciencefocus.com/article/mind/qa-sleep-paralysis-and-exploding-head-syndrome">BBC Focus</a> and <a href="http://briansharpless.com/index.html">Brian Sharpless</a>, a leading expert on this phenomenon, to collect data on this topic. </p>
<h2>Imps and ghouls</h2>
<p>Finally, what might scientists make of precognitive dreams? We might dream of a friend we haven’t seen for years only to have them call us the very next day. French thinks science can provide an explanation for this too. Referencing work by John Allen Paulos that focuses on probabilities, <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.117.8727&rep=rep1&type=pdf">he explains</a> how such an occurrence may be surprising on any single day, but over time, quite likely to occur. </p>
<p>Researching my book, I spoke to Mrs Sinclair, who is 70, and lives alone. She told me about what she had thought was a ghost living in her house, an imp throttling her during the night and other things that had left her petrified. Having scientific explanations provided her with immense comfort and she no longer believes in paranormal explanations for the things that she experienced. </p>
<p>Our hope is that scientific explanations of paranormal experiences might help others by lowering anxiety. Decreasing anxiety has also been <a href="http://www.smrv-journal.com/article/S1087-0792(17)30112-0/pdf">hypothesised</a> as a potential method by which to reduce sleep paralysis. So, perhaps providing more information about these unusual experiences might even mean that things are less likely to go bump in the night.</p><img src="https://counter.theconversation.com/content/93534/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alice M. Gregory is Professor of Psychology at Goldsmiths, University of London. Her book Nodding Off: The Science of Sleep from Cradle to Grave, on which this article is based, was published by Bloomsbury in June, 2018. She has provided guidance and educational content for babysleep.com, a website partially supported by Johnson and Johnson, who do not have any influence over content and do not advertise on it. She has previously received funding to support her work from multiple sources including the MRC, ESRC, Leverhulme Trust and the British Academy. </span></em></p>Sleep paralysis and exploding head syndrome can help explain things that go bump in the night.Alice M Gregory, Professor of Psychology, Goldsmiths, University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/919592018-03-08T11:44:07Z2018-03-08T11:44:07ZWant better sex? Try getting better sleep<figure><img src="https://images.theconversation.com/files/208694/original/file-20180302-65544-1e7umuo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sleep affects sex, and sex affects sleep. It's important to pay attention to both. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/side-view-beautiful-young-couple-sleeping-499192603?src=yH4KX0edA356PgbPhELeKA-1-4">VGstockstudio/Shutterstock.com </a></span></figcaption></figure><p><a href="https://www.cdc.gov/media/releases/2016/p0215-enough-sleep.html">One in 3 American adults</a> do not get enough sleep. Sexual issues are also common, with as many as <a href="https://link.springer.com/article/10.1007/s11920-996-0006-2">45 percent of women and 31 percent of men</a> having a concern about their sex life. While these might seem like distinct concerns, they are actually highly related. </p>
<p>How are sleep and sex related? I’ll state the obvious: We most commonly sleep and have sex in the same location – the bedroom. Less obvious but more important is that lack of sleep and lack of sex share some common underlying causes, including stress. Especially important, lack of sleep can lead to sexual problems and a lack of sex can lead to sleep problems. Conversely, a good night’s sleep can lead to a greater interest in sex, and orgasmic sex can result in a better night’s sleep.</p>
<p>I am a sex educator and researcher who has published several studies on the effectiveness of self-help books in enhancing sexual functioning. I have also written two sexual self-help books, both based in research findings. My latest book, “<a href="http://drlauriemintz.com/books/becoming-cliterate/">Becoming Cliterate: Why Orgasm Equality Matters – and How to Get It</a>,” is aimed at empowering women to reach orgasm. More pertinent to the connection between sleep and sex, my first book, “<a href="http://drlauriemintz.com/books/a-tired-womans-guide-to-passionate-sex/">A Tired Woman’s Guide to Passionate Sex</a>,” was written to help the countless women who say they are too exhausted to be interested in sex. </p>
<h2>The effect of sleep on sex among women</h2>
<p>The reason I wrote a book for women who are too tired for sex is because women are disproportionately affected by both sleep problems and by low sexual desire, and the relationship between the two is indisputable. <a href="https://sleepfoundation.org/sleep-topics/women-and-sleep">Women are more likely than men to have sleep problems</a>, and <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1471-0528.2002.01002.x/full">the most common sexual complaint that women bring to sex therapists and physicians is low desire</a>. Strikingly, being too tired for sex is the top reason that women give for their loss of desire. </p>
<p>Conversely, getting a good night’s sleep can increase desire. <a href="http://onlinelibrary.wiley.com/doi/10.1111/jsm.12858/full">A recent study</a> found that the longer women slept, the more interested in sex they were the next day. Just one extra hour of sleep led to a 14 percent increase in the chances of having a sexual encounter the following day. Also, in this same study, more sleep was related to better genital arousal. </p>
<p>While this study was conducted with college women, those in other life stages have even more interrelated sleep and sex problems. Menopause involves a complicated interaction of biological and psychological issues that are associated with both sleep and sex problems. Importantly, <a href="http://online.liebertpub.com/doi/pdf/10.1089/jwh.2009.1800">a recent study</a> found that among menopausal women, sleep problems were directly linked to sexual problems. In fact, sleep issues were the only menopausal symptom for which such a direct link was found. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/208730/original/file-20180302-65544-z1986.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/208730/original/file-20180302-65544-z1986.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/208730/original/file-20180302-65544-z1986.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/208730/original/file-20180302-65544-z1986.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/208730/original/file-20180302-65544-z1986.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/208730/original/file-20180302-65544-z1986.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/208730/original/file-20180302-65544-z1986.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Motherhood is great, but the demands of a new baby can exhaust a new mother. Sleep can become more appealing than sex as a result.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-mother-holding-her-newborn-child-329743067?src=f1ribZpMHQnw-hVqRW2jGg-1-13">FamVeld/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>Interrelated sleep and sexual issues are also prevalent <a href="https://sleepfoundation.org/sites/default/files/Poll%20Release%20-%20FINAL.pdf">among mothers</a>. Mothers of new babies are the least likely to get a good night’s sleep, mostly because they are caring for their baby during the night. However, ongoing sleep and sexual issues for mothers are often caused by having too much to do and the associated stress. Women, who are married with school-age children and working full time, are the most likely to report insomnia. Still, part-time working moms and moms who don’t work outside the home report problems with sleep as well.</p>
<p>While fathers also struggle with stress, there is <a href="https://www.ncbi.nlm.nih.gov/pubmed/10825779">evidence</a> that stress and the <a href="http://www.apa.org/news/press/releases/stress/2010/gender-stress.pdf">resulting sleepless nights</a> dampen women’s sexual desire more than they do men’s. Some of this is due to hormones. Both <a href="https://www.ncbi.nlm.nih.gov/pubmed/9415946">insufficient sleep</a> and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2703719/">stress</a> result in the release of cortisol, and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880087/">cortisol decreases testosterone</a>. Testosterone plays a major role in the sex drive of women and men. Men have significantly more testosterone than women. So, thinking of testosterone as a tank of gas, the cortisol released by stress and lack of sleep might take a woman’s tank to empty, yet only decrease a man’s tank to half full. </p>
<h2>The effect of sleep on sex among men</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/208731/original/file-20180302-65547-kslsni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/208731/original/file-20180302-65547-kslsni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/208731/original/file-20180302-65547-kslsni.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/208731/original/file-20180302-65547-kslsni.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/208731/original/file-20180302-65547-kslsni.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/208731/original/file-20180302-65547-kslsni.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/208731/original/file-20180302-65547-kslsni.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Even young men can lose interest in sex if they are sleep-deprived.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/front-view-tired-man-sleeping-on-339327623?src=SqCH9BDwf03dBpL7NNHsjA-1-32">Antonio Guillem/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>Although lack of sleep and stress seems to affect women’s sexual functioning more than men’s, men still suffer from interrelated problems in these areas. <a href="https://jamanetwork.com/journals/jama/fullarticle/1029127">One study</a> found that, among young healthy men, a lack of sleep resulted in decreased levels of testosterone, the hormone responsible for much of our sex drive. <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1743-6109.2009.01372.x/full">Another study</a> found that among men, sleep apnea contributed to erectile dysfunction and an overall decrease in sexual functioning. Clearly, among men, lack of sleep results in diminished sexual functioning. </p>
<p>I could not locate a study to prove this, as it stands to reason that the reverse is also true. That is, it seems logical that, as was found in the <a href="http://onlinelibrary.wiley.com/doi/10.1111/jsm.12858/full">previously mentioned study among women</a>, for men a better night’s sleep would also result in better sexual functioning.</p>
<h2>The effect of sex on sleep</h2>
<p>While sleep (and stress) have an effect on sex, the reverse is also true. That is, sex affects sleep (and stress). <a href="https://www.cnn.com/2017/06/01/health/sex-sleep-kerner/index.html">According to sex expert Ian Kerner</a>, too little sex can cause sleeplessness and irritability. Conversely, there is some <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2703719/">evidence</a> that the stress hormone cortisol decreases after orgasm. There’s also <a href="https://www.cqu.edu.au/cquninews/stories/research-category/2016/can-sex-be-repositioned-as-a-sleep-therapy">evidence</a> that oxytocin, the “<a href="https://www.psychologytoday.com/basics/oxytocin">love hormone</a>” that is released after orgasm, results not only in increased feelings of connection with a partner, but in better sleep. </p>
<p>Additionally, <a href="https://www.cnn.com/2017/06/01/health/sex-sleep-kerner/index.html">experts claim</a> that sex might have gender-specific effects on sleep. Among women, orgasm increases estrogen, which leads to deeper sleep. Among men, the hormone prolactin that is secreted after orgasm results in sleepiness.</p>
<h2>Translating science into more sleep and more sex</h2>
<p>It is now clear that a hidden cause of sex problems is sleeplessness and that a hidden cause of sleeplessness is sex problems. This knowledge can lead to obvious, yet often overlooked, cures for both problems. Indeed, experts have suggested that <a href="http://online.liebertpub.com/doi/pdf/10.1089/jwh.2009.1800">sleep hygiene can help alleviate sexual problems</a> and that <a href="https://www.cqu.edu.au/cquninews/stories/research-category/2016/can-sex-be-repositioned-as-a-sleep-therapy">sex can help those suffering from sleep problems</a>. </p>
<p>Perhaps, then, it is no surprise that both sleep hygiene suggestions and suggestions for enhanced sexual functioning have some overlap. For example, <a href="https://www.cnn.com/2017/06/01/health/sex-sleep-kerner/index.html">experts suggest</a> sticking to a schedule, both for sleep and for sexual encounters. They also recommend decreasing smartphone usage, both before bed and when spending time with a partner. The bottom line of these suggestions is to make one’s bedroom an exclusive haven for the joys of both sleep and sex.</p><img src="https://counter.theconversation.com/content/91959/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Laurie Mintz does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Research demonstrates a two-way relationship between sleep problems and sexual problems, as well as between satisfying sex and sound sleep. If you want better sex, you need better sleep.Laurie Mintz, Professor of Psychology, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/813292017-09-05T20:08:17Z2017-09-05T20:08:17ZCurious Kids: Why do our brains freak us out with scary dreams?<figure><img src="https://images.theconversation.com/files/180155/original/file-20170728-5404-2f34yj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dreams are like a forest walkway: there's no clear sense of direction and you can easily get lost.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/ollierb/14758863162/in/photostream/">ollierb/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p><em>This is an article from <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!</em> </p>
<hr>
<blockquote>
<p><strong>Why do our brains freak us out with scary dreams? – Niamh, 8, Newcastle.</strong></p>
</blockquote>
<p>Great question, Niamh.</p>
<p>Getting a fright from a dream is very normal. But our brains don’t have a secret plan to freak us out with nightmares.</p>
<p>In the olden days, many people believed dreams were a window to another world. People lived two inseparable lives: one in a waking world and the other in a dream world. </p>
<p>They believed the dream world contained a mixture of the past and the future, gods and goddesses, and helped people find purpose with their lives. These dreams often revealed new people and ideas, which explains why some people found them scary. Others saw them as a sign or a prophesy from the gods. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/180485/original/file-20170801-766-gyvwbi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/180485/original/file-20170801-766-gyvwbi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/180485/original/file-20170801-766-gyvwbi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/180485/original/file-20170801-766-gyvwbi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/180485/original/file-20170801-766-gyvwbi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/180485/original/file-20170801-766-gyvwbi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/180485/original/file-20170801-766-gyvwbi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/180485/original/file-20170801-766-gyvwbi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The dreamcatcher is a Native American invention used to protect people while they sleep.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/bsheets/294218008/">bsheets/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>When scientists first studied dreams, around 200 years ago, they thought dreams were a special type of story that brains told themselves. Scientists thought it was a special language where ideas and emotions were explained using symbols and signs. Different parts of the brain would talk with other parts in this dream state. </p>
<p>If your house was damaged, for example, it was supposed to represent the dreamer, and the brain was trying to tell you that you or your ego had been damaged. Dr Sigmund Freud, seen by many as the founder of psychoanalysis, wrote a very famous book about dreams called “<a href="https://pdfs.semanticscholar.org/a342/beb8bc59dc106f7a7f3f4336a00c0a61ba2f.pdf">The Interpretation of Dreams</a>” in 1900.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/180483/original/file-20170801-12621-762qqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/180483/original/file-20170801-12621-762qqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/180483/original/file-20170801-12621-762qqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/180483/original/file-20170801-12621-762qqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/180483/original/file-20170801-12621-762qqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/180483/original/file-20170801-12621-762qqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/180483/original/file-20170801-12621-762qqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/180483/original/file-20170801-12621-762qqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sigmund Freud wrote a very famous book about dreams called The Interpretation of Dreams.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/Category:Sigmund_Freud#/media/File:Sigmund_Freud_1926.jpg">Wikimedia</a></span>
</figcaption>
</figure>
<p>About 100 years ago, people started to explain things more thoroughly using science and technology. This brought a different way of understanding why things happen. But it doesn’t mean the way other people thought about dreams was necessarily wrong.</p>
<p>There are two main types of sleep, according to scientists, and dreams occur during a stage called REM sleep (Rapid Eye Movement).</p>
<p>REM sleep is when we are most likely to dream. It is called REM because people quickly flick their eyes back and forward while they sleep. </p>
<p>If you watch cats or dogs sleeping, you will sometimes see their eyes moving and their paws twitching. This indicates they are in REM sleep and probably dreaming. But we don’t really know what cats and dogs dream about because they can’t tell us.</p>
<iframe src="https://giphy.com/embed/HhRGUdBJ5RVT2" width="100%" height="270" frameborder="0" class="giphy-embed" allowfullscreen=""></iframe>
<p><a href="https://giphy.com/gifs/dreaming-cat-HhRGUdBJ5RVT2"></a></p>
<p>The other main type of sleep is non-REM sleep, called deep sleep or Slow Wave Sleep (SWS). In this type, people sleep very deeply. But they don’t typically report dreaming. If you try to wake them, they’re often slow and confused. </p>
<p>For the last 50 years, some scientists believed that dreaming was the way brains decide what to keep and what to throw away each day. In a sense, it’s like cleaning your room: your brain decides what you’ll need to know and tosses the unimportant stuff into the bin.</p>
<p>Scientists think young people find it harder to separate the waking and dreaming worlds and often <a href="https://en.wikipedia.org/wiki/Dream">confuse the two</a>.</p>
<p>Filmmakers have taken this confusion to the screen again and again over the years. There are many movies about how dreams can scare and confuse us. </p>
<p>As you can see, lots of people wonder why dreams are scary. The truth is that we don’t know for sure. </p>
<p>What we do know is that all people dream, and all people think dreams can be weird, scary and puzzling at times. We share the ability to dream with all <a href="https://en.wikipedia.org/wiki/Sleep_in_non-human_animals">warm-blooded animals</a>, so it likely has an important function in keeping us healthy. </p>
<p>I suspect everyone tries to make sense of their dreams — even scientists. But we still can’t see inside someone else’s brain to see what they are dreaming about. And that’s probably a good thing.</p>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:</em></p>
<p><em>* Email your question to curiouskids@theconversation.edu.au
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* Tell us on <a href="https://twitter.com/ConversationEDU">Twitter</a> by tagging <a href="https://twitter.com/ConversationEDU">@ConversationEDU</a> with the hashtag #curiouskids, or
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p><em>Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/81329/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Drew Dawson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Niamh, age 7, wants to know why we have scary dreams. But after 200 years of study, dreams are still very much a mystery.Drew Dawson, Director, Appleton Institute, CQUniversity AustraliaLicensed as Creative Commons – attribution, no derivatives.