tag:theconversation.com,2011:/au/topics/chemical-messengers-19612/articlesChemical messengers – The Conversation2016-08-16T03:08:58Ztag:theconversation.com,2011:article/636922016-08-16T03:08:58Z2016-08-16T03:08:58ZParasitic flies, zombified ants, predator beetles – insect drama on Mexican coffee plantations<figure><img src="https://images.theconversation.com/files/134030/original/image-20160814-25467-iyspqn.jpg?ixlib=rb-1.1.0&rect=0%2C543%2C1648%2C1112&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Azteca ants, unsung heroes of coffee pest control.</span> <span class="attribution"><span class="source">Kate Mathis</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Ants are voracious predators and often very good at defending plants from herbivores. People have taken advantage of this quirk for centuries. In fact, using ants in orange groves is one of the <a href="http://www.jstor.org/stable/1310713">first recorded pest control practices</a>, dating back to A.D. 304 in China.</p>
<p>In southern Mexico, Azteca ants are frequently found on coffee plantations. They live in giant nests built into the sides of the hardwood trees farmers plant to shade the delicate coffee plants below. The ants feast on sugary nectar, either directly from extrafloral nectary structures on the shade trees or indirectly from nectar excreted by aphids living on the coffee plants. In return the ants remove other insects to protect the plants. The Azteca ants are highly territorial and very aggressive, which makes them great at controlling coffee pests. They’re particularly skilled in eliminating one of the coffee’s most damaging pests, <a href="https://www.youtube.com/watch?v=czg1FjGBJqc">the coffee berry borer</a>.</p>
<p>My colleagues and I are <a href="http://doi.org/10.1525/bio.2010.60.7.8">studying how these ants are at the center</a> of a complex web of organisms that are important to coffee management. In the process, we serendipitously discovered a brand new species that may be integral to the ants’ success.</p>
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<span class="caption">Coffee plantation Finca Irlanda in Chiapas, Mexico.</span>
<span class="attribution"><span class="source">Kate Mathis</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<h2>Ants must deal with parasitizing flies</h2>
<p>For the last six years, I’ve been examining the dynamics between these beneficial ants and one of their most deadly natural enemies, phorid fly parasitoids.</p>
<p>On the surface, it’s hard to imagine that phorid flies could have a big impact on a mighty Azteca colony made up of millions of workers. For one, these flies are small, approximately the size of a pinhead. Also, it takes only a fraction of a second for an adult phorid fly to parasitize an ant by laying its egg in the ant’s body. </p>
<p>But these parasitoids are definitely bad news for the ants. Once a phorid fly injects its egg into the ant, the fly larva slowly makes its way into the ant’s head, ultimately consuming the contents and killing the ant in the process. Then it decapitates the ant and uses the head as a pupal case. Once fully mature, the adult fly will emerge from the ant’s mouth parts to begin the cycle again.</p>
<p>This gruesome process isn’t even the worst of it for the ants. Phorid flies aren’t just a death sentence for a parasitized individual ant, they also negatively affect the function of the ant colony as a whole. When ant workers discover phorid flies nearby, they freeze in place or hide, preventing them from collecting food or properly maintaining their nest.</p>
<h2>Enter: A mysterious beetle</h2>
<p>It was during an experiment in the field, watching phorid flies parasitize ants, that I first noticed the beetles.</p>
<p>I had hypothesized that phorid flies usurp the ants’ own complex chemical communication system to locate their victims; I was testing extracts from different ant glands to determine what chemicals the flies might use as a beacon to find their ant hosts.</p>
<p>I had dissected and extracted the Pygidial gland sac of the ants, which houses their alarm pheromone. The ants secrete this chemical blend whenever they’re injured or discover an intruder to the nest. (It’s quite pungent, and smells vaguely of blue cheese.) I was finding that the <a href="http://doi.org/10.1007/s10905-010-9247-3">phorid flies are attracted to these alarm compounds</a>. Shortly after the chemicals are released into the air, the flies arrive to inspect the immediate area where the scent is strongest. Annoyingly, I was also finding that tiny beetles were apt to crash the party, landing in my observation area with the ants.</p>
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<span class="caption">Beetles discovered in phorid rearing chambers after eating ants.</span>
<span class="attribution"><span class="source">Kate Mathis</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>A year or so later, I was working on another phorid fly-rearing experiment in my tiny lab space at the Finca Irlanda research station in Chiapas, Mexico. My lab consisted of a few shelves and a small work table in a poorly screened-in porch area. The experiments involved taking parasitized ants and keeping them alive in tiny chambers with small air holes until the phorid flies could fully develop and hatch.</p>
<p>But everything was going extremely poorly. Over and over again, I would check on my parasitized ants only to find them missing, and in their place, once again, the tiny beetles. It seemed these intruders were entering my lab, accessing the rearing chambers via the air holes and eating the ants.</p>
<p>This is when I realized something interesting was happening and started formulating questions. What were these beetles? Are they finding the ants the same way the phorid flies do? Are they only eating parasitized ants? If so, why?</p>
<h2>Predation that could help the colony</h2>
<p>Since Azteca ants are so aggressive, it seemed unlikely that a beetle would be able to effectively prey on healthy worker ants twice its size. Myrmecophillic (“ant associated” or literally “ant-loving”) beetles use a wide range of strategies to live closely with such dangerous creatures as ants. Some mimic the smell or look of ants, others use particularly swift movements to outmaneuver them and others use ant-repellent secretions to create a protective force field around themselves. In each of these cases, the beetles take some kind of resource from the ant, whether it’s food from the colony’s stores, or safe nesting space, or simply eating the ants themselves.</p>
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<figcaption><span class="caption">Beetles attacking parasitized ants (painted white) while ignoring healthy ants (painted green).</span></figcaption>
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<p>It occurred to me that the myrmecophillic beetles associated with Azteca might be exploiting the state of the parasitized ants in order to prey on them. Even more intriguingly, this might be a case where predation is ultimately not a bad thing for the ants as a group. Parasitized ants are already almost certainly going to die. And their deaths result in more phorid flies, which is bad for the ant colony. </p>
<p>But if a beetle eats a parasitized ant, the developing phorid fly is also consumed. By eating only parasitized ants, these beetles may be reducing the number of phorid flies that successfully develop – which could actually benefit the ant colony.</p>
<p>So I got to work conducting experiments that would untangle what’s going on. I used synthetic versions of the Azteca alarm pheromone chemicals to confirm the beetles were indeed using the alarm pheromone to find the ants, regardless of whether they were in my screened-in lab space or the center of a field of coffee. I set out various traps of parasitized, healthy or injured ants to see if the beetles would prey on only the parasitized ants (they did). </p>
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<span class="caption">Painted ants and beetles in the behavioral observation arena. Large beetle visitor on the notebook was not included in the experiments.</span>
<span class="attribution"><span class="source">Kate Mathis</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>I also took parasitized ants and healthy ants, painted them different colors and placed them in an arena with the beetles to observe what they would do. Healthy ants were highly aggressive toward the beetles, whereas the parasitized ants were extremely docile. When the beetles tried to attack healthy ants, they were swiftly rebuffed. But when they attacked parasitized ants, the ant essentially stood still <a href="http://doi.org/10.1098/rspb.2016.1281">as the beetle ate it alive</a>.</p>
<p>Meanwhile, specimens of the beetles were being transported to a beetle expert for identification. As it turned out, they were <a href="http://www.ncbi.nlm.nih.gov/pubmed/24871169">a completely new species</a>, the first from their genus to ever be recorded from Mexico. With my collaborators, I chose to name the species <em>Myrmedonota xipe</em> for the Aztec god Xipe Totec. This deity was worshiped via human sacrifices in an act meant to symbolize the casting-off of the old to bring new growth and prosperity to all – an apt metaphor for the beetles’ role in Azteca ant colonies.</p>
<p>When many people think of agriculture, they imagine only the farmer’s crop. But, my colleagues’ and my work shows that a complex web of interactions between many species of insects can provide important ecosystem services, like pest control, in agroecosystems. This particular story shows just a piece of the puzzle, where the Azteca ants are benefiting the coffee, and the beetles are helping keep the phorid flies from stopping that.</p><img src="https://counter.theconversation.com/content/63692/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kate Mathis receives funding from the National Science Foundation and National Institutes of Health. </span></em></p>Azteca ants are self-appointed protectors of coffee plants on Mexican plantations. But they have a lot to contend with from other insects.Kate Mathis, Research Associate in Ecology & Evolutionary Biology, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/569212016-06-12T19:40:47Z2016-06-12T19:40:47ZChemical messengers: how hormones change through menopause<figure><img src="https://images.theconversation.com/files/121128/original/image-20160504-5832-1neogn5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some women breeze through perimenopause and never have a symptom, whereas others have a horrid time. </span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-230712769.html">Rob Bayer/Shutterstock</a></span></figcaption></figure><p>Every woman who reaches midlife will experience menopause when her ovaries eventually run out of eggs. </p>
<p>The <a href="http://www.nature.com/articles/nrdp20154">average age</a> of natural menopause in Australia is 51 years. But around 10% of women experience menopause before the age of 45, and 1% before 40. Early menopause can be spontaneous, or due to surgical removal of both ovaries, or brought on by treatments such as chemotherapy. </p>
<p>After menopause, the ovaries are no longer able to produce the sex hormones essential for reproduction. As a result, blood levels of oestrogen and progesterone are very low. </p>
<p>Blood levels of testosterone don’t change with natural menopause, but decline in the decade leading up to the menopause. Women who have had their ovaries surgically removed have lower testosterone levels than other women. </p>
<p>The months surrounding menopause are called the perimenopause. It’s a period of hormonal chaos that generally lasts about two years. Women may experience perimenopausal symptoms that at times reflect high oestrogen levels due to the ovaries working harder: sore swollen breasts, heavy bleeding, periods closer together. </p>
<p>At other times they may have symptoms of low oestrogen due to the ovaries running down: missed periods, hot flushes, night sweats, lowered mood, anxiety and sleep disturbances.</p>
<p>Some women breeze through perimenopause and never have a symptom, whereas others have a horrid time. </p>
<h2>Symptoms</h2>
<p>Most symptoms that follow menopause are due to low oestrogen. The most common are hot flushes and night sweats, which affect <a href="http://www.med.monash.edu.au/sphpm/womenshealth/docs/bulletin/december-2014.pdf">three-quarters</a> of post-menopausal women and are severely bothersome for one in three women. </p>
<p>Most women will have hot flushes and night sweats <a href="http://www.ncbi.nlm.nih.gov/pubmed/26450529">for an average of</a> 4.5 years after their menopause, although many women have symptoms into their 60s. Contrary to some beliefs, <a href="http://www.ncbi.nlm.nih.gov/pubmed/26926325">women in developing and developed countries</a> experience hot flushes and night sweats; they’re not symptoms of westernisation. </p>
<p>Other common symptoms of perimenopause and menopause include mood changes (anxiety and depressed mood), vaginal dryness resulting in painful intercourse, frequent urination and sexual dysfunction, particularly lowered libido. </p>
<p>Women start to lose <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2869543/">bone</a> around two years before menopause. This accelerates during perimenopause, and slows about two to seven years after menopause. Low body weight is a major risk factor for bone loss at this time. </p>
<p>Menopause-related bone loss occurs because the fall in oestrogen production accelerates bone breakdown, which is not compensated for by bone formation. Bone loss can, however, be prevented or reversed by oestrogen therapy. </p>
<p>Menopause also results in metabolic changes that may predispose women to heart disease and diabetes.</p>
<h2>Treatment</h2>
<p>Severe menopausal symptoms can be debilitating. Moderate to severely bothersome hot flushes and night sweats are associated with <a href="http://www.maturitas.org/article/S0378-5122(15)00706-9/abstract">lowered personal and general well-being</a> and an <a href="http://www.maturitas.org/article/S0378-5122(16)30018-4/abstract">impaired ability to work</a>. </p>
<p>Thankfully, women can choose from a range of effective hormonal and non-hormonal treatments to alleviate symptoms. Her choice will be based on how bothered she is by the symptoms, her current health status and her personal expectations. </p>
<p>Menopausal hormone therapy is the most effective treatment option, but comes with an increased risk of some cancers if used for extended periods. However, it is <a href="http://www.nejm.org/doi/full/10.1056/NEJMp1514242">internationally accepted</a> that for most women within ten years of menopause and or who are less than 60 years of age, the benefits of menopausal hormone therapy outweigh the risks. </p>
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<p>Unfortunately, myths of the dangers of menopausal hormone therapy have been widely and inappropriately propagated, resulting in many women with severe symptoms <a href="http://www.ncbi.nlm.nih.gov/pubmed/26240945">not receiving effective treatment</a>. It has also prompted some women to resort to <a href="https://theconversation.com/trick-or-treat-alternative-therapies-for-menopause-18007">complementary therapies</a> that lack proven efficacy, and untested and unregulated <a href="https://theconversation.com/natural-hormone-therapy-no-panacea-for-menopause-symptoms-25869">compounded hormone therapy</a>. </p>
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<p>Compounded hormones are promoted as being “bioidentical”, but they are made using the same hormones used in approved menopausal hormone therapy. There is no evidence that compounded hormone therapy is more or less safe than approved therapies, although it is usually more expensive and the hormonal blood levels cannot be predicted.</p>
<p>Non-hormonal treatment options to reduce hot flushes and night sweats include <a href="http://www.tandfonline.com/doi/pdf/10.3109/13697137.2014.929651">low-dose antidepressants</a> the anti-epliepsy medicine <a href="http://www.nps.org.au/medicines/brain-and-nervous-system/antiepileptic-medicines/gabapentin">gabapentin</a> and the neuropathic pain drug <a href="https://www.nlm.nih.gov/medlineplus/druginfo/meds/a605045.html">pregabalin</a>. But none are as effective as standard dose hormone therapy. Other <a href="http://www.queoncology.com">potential non-hormonal therapies</a> to alleviate hot flushes are being investigated. </p>
<p><a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3556367/">Hypnosis</a> and <a href="http://www.ncbi.nlm.nih.gov/pubmed/24144959">cognitive behaviour therapy</a> have been shown to have some benefit for hot flushes and night sweats. However, quality clinical studies have not shown yoga, exercise or <a href="http://annals.org/article.aspx?articleid=2481811">acupuncture</a> to be more effective than placebo therapy. </p>
<hr>
<p><em>This article is part of an occasional series, <a href="https://theconversation.com/au/topics/chemical-messengers">Chemical Messengers</a>, on hormones and the body.</em></p><img src="https://counter.theconversation.com/content/56921/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Susan Davis has received honoraria from Abbott and Pfizer. She receives funding from the NHMRC, the National Breast Cancer Foundation, the Grollo-Ruzenne Foundation, the Bupa Health Foundation and Lawley Pharmaceuticals. She is affiliated with the International Menopause Society, the Endocrine Society and the Australasian Menopause Society. </span></em></p>Every woman who reaches midlife will experience menopause when her ovaries eventually run out of eggs. So what’s happening with her hormones?Susan Davis, Chair of Women's Health, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/523052016-03-29T19:07:00Z2016-03-29T19:07:00ZChemical messengers: how pregnancy hormones affect the body<figure><img src="https://images.theconversation.com/files/114397/original/image-20160309-22114-qp4t9c.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">What are the hormones that cause cravings during pregnancy?</span> <span class="attribution"><span class="source">from www.shutterstock.com.au</span></span></figcaption></figure><blockquote>
<p>The breasts go first, and then the waist and then the butt. Nobody ever tells you that you get a butt when you get pregnant. – <a href="https://books.google.com.au/books/about/Oh_Baby_I_m_Having_a_Baby.html?id=YNSPNIwcNdAC&redir_esc=y">Elle Macpherson</a>.</p>
</blockquote>
<p>Multiple hormones produced by the mother, placenta and the foetus drive and coordinate the amazing biological changes and development of the baby that occur with conception, foetal growth and birth.</p>
<p>The word “hormone” is <a href="http://www.etymonline.com/index.php?term=hormone">derived from the Greek word</a> “<em>hormon</em>” which means “to urge on or that which sets in motion”. As any mother will tell you, the nine months of pregnancy is quite a journey.</p>
<p>During pregnancy, there are significant changes in the mother including changes to heart and kidney function, increases in body fat and fluid retention, changes in skin and psychological changes, as well as the obvious changes to the uterus and breasts.</p>
<p>Basically, all organs in the mother’s body are required to increase their workload to help with the pregnancy and the development of the baby.</p>
<p>These maternal changes are due to hormones being produced by the mother’s glands and the placenta – hormones such as oestrogen, progesterone, prolactin, renin, human chorionic gonadotropin and human placental lactogen.</p>
<p>We now understand that if a baby develops in an unhealthy uterine environment, this can not only lead to problems at birth, but also increased risks of diseases, such as diabetes and heart disease, when the baby becomes an adult.</p>
<p>The more we understand the changes to the mother’s body, the better the advice will be from health professionals, and the more medical treatment can help when diseases occur, all leading to better outcomes for mother and baby. </p>
<h2>Heart and kidney function</h2>
<p>Throughout pregnancy there is an increase in the amount of blood the heart pumps each minute. Dilation and relaxation of blood vessels, due to hormones such as oestrogen and relaxin, results in a lowering of blood pressure. There is also an increase in kidney blood flow. </p>
<p>Activation of the renin-angiotensin system, an important system to control normal fluid balance and blood pressure, leads to fluid retention in the pregnant mother. This can manifest as ankle and hand swelling. Despite more fluid being retained, the mother’s blood pressure normally does not rise. In fact, it falls due to the dilation of blood vessels as discussed above.</p>
<p>Increases in total blood volume and circulating red cells occur throughout pregnancy. This is due to a stimulation of red cell formation caused by increases in erythropoietin, a hormone secreted by the kidney that controls the number of red cells circulating in the blood.</p>
<h2>Skin changes</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/114406/original/image-20160309-22138-9jsv4j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114406/original/image-20160309-22138-9jsv4j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/114406/original/image-20160309-22138-9jsv4j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114406/original/image-20160309-22138-9jsv4j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114406/original/image-20160309-22138-9jsv4j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114406/original/image-20160309-22138-9jsv4j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114406/original/image-20160309-22138-9jsv4j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114406/original/image-20160309-22138-9jsv4j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Melasma blemish.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Melasma">Wikimedia commons</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>As pregnancy progresses some women notice pigmentation of the skin, often involving the face, called melasma, which fades away generally a few months after the birth.</p>
<p>Melasma is due to increased skin pigmentation produced by the pigment-forming cells (melanocytes). </p>
<p>Small dilated skin blood vessels, thought to be related to the high level of oestrogens, can develop during pregnancy and regress after birth.</p>
<h2>Breast and uterine development</h2>
<p>In preparation for lactation (breast feeding), breast tissue, including milk ducts, areola and nipples, increases in size due to hormones such as oestrogen, prolactin and human placental lactogen. </p>
<p>High oestrogen and progesterone levels during pregnancy inhibit any significant lactation. However, some women notice nipple discharge (colostrum) towards the end of pregnancy.</p>
<p>Following delivery, when levels of hormones such as progesterone fall, breast milk production increases and lactation occurs (the mother’s milk comes in). Prolactin levels remain high during lactation due to ongoing stimulation from suckling.</p>
<p>Placental hormones such as human chronic gonadotropin (the hormone that is detected in urine tests to confirm a pregnancy), human placental lactogen, placental growth hormone, oestrogen and progesterone are produced to maintain the pregnancy. </p>
<p>These hormones encourage foetal and uterine growth, encourage transfer of maternal nutrients for foetal fuel metabolism, and increase blood supply across the placenta to the foetus.</p>
<h2>Increase in body fat</h2>
<p>About half the mother’s weight gain during pregnancy is due to increases in body fat, a fuel source required for the increased demands of pregnancy and in preparation for breastfeeding, although the hormonal mechanisms for these changes are not completely understood. </p>
<p>The ideal weight to gain during pregnancy has <a href="http://c.ymcdn.com/sites/www.chronicdisease.org/resource/resmgr/Womens_Health_Council_GDM/Weight_Gain_in_Pregnancy_Bar.pdf">recently been debated</a>, especially in women who are overweight pre-pregnancy. Too much fat gain in pregnancy can lead to poor maternal and baby outcomes, so careful dietary advice and planning are required. It may be that women store fat more efficiently in pregnancy, so pregnant women <a href="http://onlinelibrary.wiley.com/doi/10.1111/ajo.12398/abstract">don’t really need to be</a> “eating for two”.</p>
<h2>Psychological changes</h2>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/114409/original/image-20160309-22143-1hzzxva.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114409/original/image-20160309-22143-1hzzxva.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/114409/original/image-20160309-22143-1hzzxva.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114409/original/image-20160309-22143-1hzzxva.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114409/original/image-20160309-22143-1hzzxva.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114409/original/image-20160309-22143-1hzzxva.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114409/original/image-20160309-22143-1hzzxva.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114409/original/image-20160309-22143-1hzzxva.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">Some women develop symptoms of depression during pregnancy, not just after it.</span>
<span class="attribution"><span class="source">from www.shutterstock.com</span></span>
</figcaption>
</figure>
<p>Maternal mood changes during pregnancy can range from joy to anxiety to depression related to the expectations of the pregnancy, physical changes, tiredness, difficulty sleeping and worry about the pregnancy, birth and the early post-birth months. </p>
<p>Fluctuating hormone levels can also have impacts on mood. Post-partum depression is well recognised and it should be watched for and managed appropriately. However, some women can develop <a href="https://www.beyondblue.org.au/for-me/pregnancy-and-early-parenthood/mental-health-conditions/depression">symptoms suggestive of depression</a> during pregnancy. Medical help should be sought if these appear.</p>
<h2>Other hormone changes</h2>
<p>Thyroid function alters especially in the first trimester in normal pregnancy and thyroid disease is not uncommon in pregnancy. Maternal iodine requirements increase, leading to pregnant women being advised to take iodine supplements. </p>
<p>Resistance to insulin, the hormone that helps glucose (sugar) metabolism, leads to glucose intolerance in the second half of pregnancy. Gestational diabetes occurs in up to 8% of pregnancies.</p>
<p>Significant changes occur to maternal biology, metabolism and body composition during pregnancy. Maintaining optimal maternal health is very important for a healthy outcome for mother and child.</p><img src="https://counter.theconversation.com/content/52305/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tony O'Sullivan 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>Multiple hormones produced by the mother, placenta and the foetus drive and coordinate the amazing biological changes and development of the baby that occur with conception, foetal growth and birth.Tony O'Sullivan, Head, Department of Endocrinology, St George and Sutherland Hospitals, and UNSW Medicine., UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/424222015-10-01T20:13:31Z2015-10-01T20:13:31ZChemical messengers: how hormones affect our mood<figure><img src="https://images.theconversation.com/files/95483/original/image-20150921-19274-2bzqjv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some women are very sensitive to small shifts in hormones, others aren't. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/gagilas/8117584487/">Petras Gagilas/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>“It’s that time of the month – stay away from her!” </p>
<p>The process of shedding the uterine lining with vaginal bleeding every month has an obvious reproductive focus, but it has also long been linked with changes to mood and behaviour. Unfortunately, this has often been an attempt to consign women to a “biologically” determined place of inferior mental functioning.</p>
<p>In recent times, we have learnt more about the connections between the “reproductive” or gonadal hormones and the brain, and how they affect not only women but men as well. </p>
<p>Gonadal hormones (oestrogen, progesterone and testosterone) are produced by the gonads (the ovaries and testes) in response to other precursor hormones found in the pituitary gland and other brain areas. These gonadal hormones impact brain chemistry and circuitry, and hence influence emotions, mood and behaviour. </p>
<h2>Women’s hormones</h2>
<p>Oestrogen appears to be a “protective” agent in the brain. This may in part explain why some women feel worse, in terms of their mental state, in the low-oestrogen phase of their monthly cycle. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/96894/original/image-20151001-5869-1ke5waq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/96894/original/image-20151001-5869-1ke5waq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=301&fit=crop&dpr=1 600w, https://images.theconversation.com/files/96894/original/image-20151001-5869-1ke5waq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=301&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/96894/original/image-20151001-5869-1ke5waq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=301&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/96894/original/image-20151001-5869-1ke5waq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=378&fit=crop&dpr=1 754w, https://images.theconversation.com/files/96894/original/image-20151001-5869-1ke5waq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=378&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/96894/original/image-20151001-5869-1ke5waq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=378&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A ‘classic’ 28 day cycle – though many women have shorter or longer cycles.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-162580289/stock-vector-menstrual-cycle-hormone-level-average-menstrual-cycle-follicular-phase-ovulation-luteal-phase.html">Tefi/Shutterstock</a></span>
</figcaption>
</figure>
<p>Oestrogen appears to have direct impacts on dopamine and serotonin, the key brain chemicals associated with the development of depression and psychosis. In fact, animal and <a href="http://www.ncbi.nlm.nih.gov/pubmed/18678800">clinical studies</a> show that administering oestradiol (the most potent form of oestrogen) can improve symptoms of psychosis and depression. </p>
<p>The concept of PMS (premenstrual syndrome) has its believers and non-believers. But essentially, there is a group of women who experience significant mental and physical symptoms in the low-oestrogen phase of their cycle every month. </p>
<p>Then there are women with crushing depression once per month that is known as <a href="http://www.med.unc.edu/psych/wmd/mood-disorders/menstrually-related#md_pmdd">premenstrual dysphoric disorder</a> (PMDD). PMDD is a serious, real depression that can rob a woman of her functioning every month. The tricky part is that it’s not always exactly the week before bleeding, nor does it last exactly a week since many women do not have the “classic” 28-day cycle with ovulation at day 14, and bleeding for five days. If life were that simple!</p>
<p>The impact of gonadal hormones on mood is apparent at many other life stages. Around puberty, a time of major hormonal change, many girls experience various mood swings and other changes in mental health. Some women who take certain types of the combined oral contraceptive experience depressive symptoms with irritability, loss of enjoyment and even suicidal thoughts.</p>
<p>Postnatal depression and <a href="http://www.blackdoginstitute.org.au/public/depression/inpregnancypostnatal/postnatalpuerperalpsychosis.cfm">psychosis</a> are key mental illnesses related to childbirth and have a major hormonal component to the onset and course of illness. This is thought to be triggered by the sudden, rapid drop in the high levels of pregnancy hormones shortly after birth.</p>
<p>During the transition to menopause, women experience major hormonal shifts. At this time, they are 14 times more likely than usual to experience depression. This is known as <a href="http://www.med.unc.edu/psych/wmd/mood-disorders/menstrually-related#md_perimen">perimenopausal depression</a>. It affects women differently than other types of depression, causing anger, irritability, poor concentration, memory difficulties, low self-esteem, poor sleep and weight gain.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/95488/original/image-20150921-20435-16zhcu2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/95488/original/image-20150921-20435-16zhcu2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=487&fit=crop&dpr=1 600w, https://images.theconversation.com/files/95488/original/image-20150921-20435-16zhcu2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=487&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/95488/original/image-20150921-20435-16zhcu2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=487&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/95488/original/image-20150921-20435-16zhcu2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=612&fit=crop&dpr=1 754w, https://images.theconversation.com/files/95488/original/image-20150921-20435-16zhcu2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=612&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/95488/original/image-20150921-20435-16zhcu2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=612&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hormones can influence our moods at different stages of life.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-174361181/stock-photo-happy-together-grandmother-with-her-daughter-and-her-granddaughter-outdoor-in-nature.html?src=bf_Yt7mjBIgcJusVoRA0WQ-1-4">Martin Novak/www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>Perimenopausal depression isn’t well recognised and is often poorly treated with standard <a href="https://theconversation.com/some-antidepressants-work-better-than-others-now-we-know-why-17850">antidepressant therapies</a>. Women with this type of depression generally respond better to hormone treatments, but the link between depression and hormones is not often made.</p>
<p>It’s also important to note that trauma and violence can lead to <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3181836/">chronically elevated levels</a> of the stress hormone cortisol, causing significant mental ill health at any time in a woman’s life. High cortisol levels have huge impacts on many brain regions, resulting in rage, suicidal thoughts, obesity and infertility.</p>
<p>There is a great deal of variation in the effects of hormone shifts on mood and behaviour. Some women are very sensitive to small shifts in gonadal hormones; others are not. </p>
<h2>Men’s hormones</h2>
<p><a href="http://www.sciencedirect.com/science/journal/10432760/12/10">Recent research</a> investigating cognition in men suggests that, just like in women, gonadal hormones influence mood and behaviour. In particular, low levels of testosterone can lead to an age-related condition called andropause. </p>
<p>Andropause is sometimes described as the “male menopause”. This is not strictly accurate since unlike female fertility, male fertility does not end abruptly with a fixed hormone decline. Andropause is caused by a significant decline in testosterone levels to below the normal range for young men. This <a href="http://www.growthhormoneigfresearch.com/article/S1096-6374(03)00061-3/abstract">can result</a> in erectile problems, diminished libido, decreased muscle strength and decreased bone mass. </p>
<p>To complicate matters, testosterone is converted to oestradiol (the most potent form of oestrogen) in men. Altered testosterone/oestradiol ratios can cause problems with memory function, depression, irritability, sleep, fatigue and occasionally even <a href="http://www.npjournal.org/article/S1555-4155(08)00522-9/abstract">hot flushes</a>.</p>
<p>There is controversy about how much of these changes are a normal part of ageing. Many other factors such as obesity, diabetes and excessive alcohol consumption can also cause low testosterone levels. So andropause should not be viewed as a disease, but as a clinical syndrome with a great deal of variability. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/96895/original/image-20151001-5873-k73jgi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/96895/original/image-20151001-5873-k73jgi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/96895/original/image-20151001-5873-k73jgi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/96895/original/image-20151001-5873-k73jgi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/96895/original/image-20151001-5873-k73jgi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/96895/original/image-20151001-5873-k73jgi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/96895/original/image-20151001-5873-k73jgi.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">Testosterone levels reduce with age.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-303241304/stock-photo-senior-hands-resting.html?src=GZ9pbd1c2opZCvLnDXfSrg-1-97">carballo/Shutterstock</a></span>
</figcaption>
</figure>
<p>In some men, testosterone-replacement has been used successfully to treat andropause. But this needs to be done under strict medical supervision because of the many potential side effects including prostate problems, elevated cholesterol and increased rage. </p>
<p>A great deal more research is required in both men and women on the role of gonadal hormones and mental health. But the era of splitting the mind from the body should be long gone. </p>
<p><em>This article is part of an occasional series, <a href="https://theconversation.com/au/topics/chemical-messengers">Chemical Messengers</a>, on hormones and the body.</em></p><img src="https://counter.theconversation.com/content/42422/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jayashri Kulkarni receives funding from the NHMRC, ARC, several pharmaceutical companies for clinical trials research. This article is independently written and has no source of funding and no conflict of interest.</span></em></p>In recent times, we have learnt more about the connections between the “reproductive” or gonadal hormones and the brain, and how they affect not only women but men as well.Jayashri Kulkarni, Professor of Psychiatry, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/355452015-09-25T04:20:43Z2015-09-25T04:20:43ZChemical messengers: how hormones make us feel hungry and full<figure><img src="https://images.theconversation.com/files/92377/original/image-20150819-10873-1ee6q7n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Whether or not you feel inclined to eat depends on the balance of the activity between two sets of neurons.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/dskley/6694869343/">Dennis Skley/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>The need to find fuel to generate energy is a profound drive within the biology of all living organisms: we all need food to survive. So it’s not surprising that our bodies have such a complex system to control food intake, driven by hormones. </p>
<p>Hormone levels also change when we lose weight. As much as we battle to trim down via diets and eating patterns, they’re also the reason most of us <a href="https://theconversation.com/weight-loss-and-the-brain-why-its-difficult-to-control-our-expanding-waistlines-3522">will regain the weight</a> we lose – or more. </p>
<p>The body’s system for regulating food intake is coordinated by the hypothalamus, which is located under the midline of the brain, behind the eyes: </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/92970/original/image-20150825-15920-129wajt.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/92970/original/image-20150825-15920-129wajt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/92970/original/image-20150825-15920-129wajt.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=707&fit=crop&dpr=1 600w, https://images.theconversation.com/files/92970/original/image-20150825-15920-129wajt.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=707&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/92970/original/image-20150825-15920-129wajt.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=707&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/92970/original/image-20150825-15920-129wajt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=889&fit=crop&dpr=1 754w, https://images.theconversation.com/files/92970/original/image-20150825-15920-129wajt.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=889&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/92970/original/image-20150825-15920-129wajt.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=889&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>Within the hypothalamus are nerve cells that, when activated, produce the sensation of hunger. They do so by producing two proteins that cause hunger: <a href="http://www.wisegeek.com/what-is-neuropeptide-y.htm">neuropeptide Y</a> (NPY) and <a href="http://medical-dictionary.thefreedictionary.com/agouti-related+peptide">agouti-related peptide</a> (AGRP). </p>
<p>Quite close to these nerve cells is another set of nerves that powerfully inhibit hunger. They produce two different proteins that inhibit hunger: <a href="https://en.wikipedia.org/wiki/Cocaine_and_amphetamine_regulated_transcript">cocaine and amphetamine-regulated transcript</a> (CART) and <a href="http://www.yourhormones.info/hormones/melanocytestimulating_hormone.aspx">melanocyte-stimulating hormone</a> (αMSH).</p>
<p>These two sets of nerve cells initiate and send hunger signals to other areas of the hypothalamus. So, whether you feel inclined to eat or not depends on the balance of the activity between these two sets of neurons. </p>
<p>But what determines which set of neurons dominates at any given time?</p>
<p>The activity is mainly controlled by hormones that circulate in the blood. These come from tissues in various parts of the body that deal with energy intake and storage, including the gut (which receives and digests the food), the fat (which stores the energy) and the pancreas (which makes hormones that are involved in energy storage, such as insulin). </p>
<h2>Hormones in the blood</h2>
<p>Let’s take a closer look at how each of these blood-circulating hormones work. </p>
<p><strong>Ghrelin</strong> is made in the stomach. It stimulates hunger by entering the brain and acting on the neurons in the hypothalamus to increase the activity of the hunger-causing nerve cells and reducing the activity of hunger-inhibiting cells. As the stomach empties, the release of ghrelin increases. As soon as the stomach is filled, it decreases. </p>
<p><strong>Insulin-like peptide 5 (ILP-5)</strong> was found to stimulate hunger in 2014. It is the second circulating hormone to have this effect and is mainly produced in the colon. But we still don’t know its physiological role. </p>
<p><strong>Cholecystokinin (CCK)</strong> is produced in the upper small bowel in response to food and gives a feeling of fullness. It is released soon after food reaches the small bowel. Researchers have found CCK can stop a mouse from eating as soon as it’s injected into the brain.</p>
<p><strong>Peptide YY, glucagon-like peptide 1 (GLP-1), oxyntomodulin and uroguanilin</strong> are all made from the last part of the small bowel and make us feel full. They are released in response to food in the gut. </p>
<p><strong>Leptin</strong> is the most powerful appetite-suppressing hormone and is made in fat cells. It was discovered in 1994. The more fat cells we have, the more leptin the body produces. </p>
<p><strong>Amylin, insulin and pancreatic polypeptide</strong> are made in the pancreas. Studies in the United States have shown that when insulin enters the brain it inhibits hunger, telling the brain “there is enough energy in the body, take a rest”. </p>
<p>Amylin, discovered in 1981, is made in the same cells that make insulin (the beta cells). It has been shown to inhibit food intake. </p>
<p>The exact role of pancreatic polypeptide is not yet known, but there is evidence that it inhibits hunger. </p>
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<p>The hypothalamus also receives signals from pleasure pathways that use <a href="http://www.utexas.edu/research/asrec/dopamine.html">dopamine</a>, <a href="http://www.sciencedaily.com/releases/2005/07/050720065810.htm">endocannabinoids</a> and <a href="http://www.medterms.com/script/main/art.asp?articlekey=5468">serotonin</a> as messengers, which influence eating behaviour.</p>
<p>Once full, the stomach reduces the desire to eat both by lowering ghrelin production and by sending a message to the hypothalamus. Ghrelin levels reach a low around 30 to 60 minutes after eating. </p>
<p>Levels of hormones that make us feel full – CCK, PYY, GLP-1, amylin and insulin – all increase following a meal to reach a peak about 30 to 60 minutes later.</p>
<p>All the hormones then gradually return to their fasting levels three to four hours after a meal.</p>
<h2>How weight loss affects our hormones</h2>
<p>Several studies have found that diet-induced weight loss is <a href="https://theconversation.com/weight-loss-and-the-brain-why-its-difficult-to-control-our-expanding-waistlines-3522">associated with</a> hormone changes that, together, promote weight regain. </p>
<p>Following weight loss, leptin levels decrease profoundly. Other hormonal changes include increases in circulating ghrelin, GIP and pancreatic polypeptide and reductions in PYY and CCK. Almost all of these changes favour regaining lost weight, by increasing hunger, reducing satiety and improving the capacity to store fat. These hormonal changes seem to be present for at least one year after weight loss, leading to a persistent increase in hunger. </p>
<p>These findings suggest suppressing hunger after weight loss – preferably with a replacement of hormones – may help people maintain their new weight. </p>
<p>Several of these agents have recently been approved by different regulatory bodies in the United States, Europe or Canada, but only one – liraglutide – is a version of one of the naturally occurring appetite suppressants (GLP-1). The ideal medication to maintain weight loss would be a long-acting mixture of three or more of the blood-circulating hormones we examined above: leptin, amylin, GLP-1, PYY, CCK and oxyntomodulin. </p>
<p>But producing such a mixture is proving a considerable challenge, so researchers continue to investigate how this might be done. </p>
<p><em>This article is part of an occasional series, <a href="https://theconversation.com/au/topics/chemical-messengers">Chemical Messengers</a>, on hormones and the body.</em></p><img src="https://counter.theconversation.com/content/35545/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joseph Proietto is Chair of The medical Advisory Board for Liraglutide 3mg for Novo Nordisk. He receives funding from the NH&MRC.</span></em></p>Our bodies have a complex system to control food intake, driven by hormones. Hormone levels also change when we gain and lose weight.Joseph Proietto, Professor of Medicine, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/449832015-09-09T04:45:31Z2015-09-09T04:45:31ZChemical messengers: how hormones help us sleep<figure><img src="https://images.theconversation.com/files/92331/original/image-20150819-12421-1sn7w0v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The activities we do during the day – from having a fight with a partner to using our iPhones at night – also affect our hormone levels and, in turn, our quality of sleep.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-194744459/stock-photo-young-beautiful-woman-sleeping-in-bed-in-closeup-shot.html?src=5CZs4Zr5KIdPffy940ybLg-6-20">Jan Faukner/Shutterstock</a></span></figcaption></figure><p>When it comes to motives for getting a good night’s sleep we don’t usually think about our body’s hormones. But sleep allows many of our hormones to replenish so we have the optimal energy, immunity, appetite and coping ability to face the day’s highs and lows.</p>
<p>The activities we do during the day – from having a fight with a partner, using our iPhones at night, running in a race, to travelling overseas – also affect our hormone levels and, in turn, our quality of sleep.</p>
<p>For both men and women, changes in our levels of sex hormones can affect how well we sleep. These differences also change with age. </p>
<p>Understanding the connections between hormones and sleep may help improve your own sleep and well-being. </p>
<h2>What are hormones?</h2>
<p>Our body’s hormones are like <a href="http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Hormonal_(endocrine)_system?open">chemical messages</a> in the bloodstream which cause a change in a particular cell or organ and surrounding tissues. The hormone <a href="http://www.yourhormones.info/Hormones/Adrenaline.aspx">adrenaline</a>, for example, is produced by the adrenal glands (on top of the kidneys) and helps prepare the body’s “fight or flight” response during times of stress. </p>
<p>Hormones control many of the <a href="http://www.pearson.com.au/9781292057200?gclid=CJzzzKGkiccCFdgnvQodjFwHxg">body’s processes</a>, including growth, development, reproduction, responding to stress, metabolism and energy balance.</p>
<p>Hormones are linked with sleep in a number of ways.</p>
<h2>Hormones affect sleep through our stress levels</h2>
<p>Some hormones, such as <a href="http://www.yourhormones.info/Hormones/Adrenaline.aspx">adrenaline</a>, make us feel more alert and prepared for action. This then makes it hard for us to go to sleep. To prevent this effect it’s best to do relaxing activities before bedtime, rather than stressful work tasks or intense exercise.</p>
<p>When stress is long lasting, <a href="http://www.sleepdex.org/acth.htm">adrenocorticotrophic hormone</a> within the pituitary gland (attached to the base of the brain) triggers the release of <a href="http://www.britannica.com/science/cortisone">cortisone</a> and <a href="http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Hormones_-_cortisol_and_corticosteroids">cortisol</a> from the adrenal glands. </p>
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<p>Levels of adrenocorticotrophic hormone tend be higher in people with <a href="https://theconversation.com/explainer-what-is-insomnia-and-what-can-you-do-about-it-36365">insomnia</a> than in good sleepers. This suggests that excessive arousal and ongoing stressors contribute to the insomnia.</p>
<p><a href="http://sock-doc.com/cortisol-and-sleep/">Elite athletes</a> can have difficulty getting to sleep because they tend to have high levels of cortisol throughout the day, including in the evening.</p>
<h2>Hormones released during sleep boost our immune system and make us hungry</h2>
<p>Sleep is a time when several of the body’s hormones are <a href="http://sleepfoundation.org/how-sleep-works/what-happens-when-you-sleep">released</a> into the bloodstream. These include growth hormone, which is essential for growth and tissue repair, including in adults. </p>
<p>Sleep helps to balance our <a href="http://sleepfoundation.org/how-sleep-works/what-happens-when-you-sleep">appetite</a> by maintaining optimal levels of the hormones <a href="http://www.ncbi.nlm.nih.gov/pubmed/17212793">ghrelin and leptin</a>. So, when we get less sleep than normal we may feel an urge to eat more. </p>
<p>Sleep also controls levels of the hormones <a href="http://draliciastanton.com/how-poor-sleep-effects-our-health-hormones-and-weight">insulin and cortisol</a> so that we wake up hungry, prompting us to eat breakfast, and we are prepared for facing daytime stress. </p>
<p>If we get less sleep than normal our levels of <a href="http://draliciastanton.com/how-poor-sleep-effects-our-health-hormones-and-weight">prolactin</a> may get out of balance and we can end up with a weakened immune system, difficulty concentrating and carbohydrate cravings during the day.</p>
<h2>Hormones stop us from having to get up in the night to go to the bathroom</h2>
<p>Changes in hormonal levels during sleep, including higher levels of aldosterone and <a href="https://myhealth.alberta.ca/health/pages/conditions.aspx?hwid=hw211268&">antidiuretic hormone</a>, prevent us from needing to go to the toilet. In children, while the hormonal system is still developing, bedwetting may be partly influenced by low levels of antidiuretic hormone.</p>
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<h2>Hormones make us feel sleepy at night</h2>
<p>Hormone levels also influence the timing of when we feel sleepy and awake – our body clock or sleep-wake cycle. The hormone melatonin is released with <a href="http://draliciastanton.com/how-poor-sleep-effects-our-health-hormones-and-weight">darkness</a> and tells our body it’s time to sleep. This is why being around too much <a href="http://sleepfoundation.org/sleep-topics/melatonin-and-sleep/page/0/1">bright light</a> before bed can affect our sleep as it can stop the release of melatonin. It’s also why it can be hard for night-time <a href="http://www.sleepeducation.com/essentials-in-sleep/shift-work/">shift workers</a> to sleep during the day. </p>
<p>While <a href="http://sleepfoundation.org/sleep-topics/melatonin-and-sleep/page/0/1">artificial melatonin</a> is available, taking the wrong dosage and at the wrong time of day can make things worse, so it’s best used with the guidance of a medical doctor.</p>
<h2>Hormones give us a wake-up call in the morning</h2>
<p>Levels of the hormone <a href="http://sleepfoundation.org/how-sleep-works/what-happens-when-you-sleep">cortisol</a> dip at bedtime and increase during the night, peaking just before waking. This acts like a <a href="http://www.brainfacts.org/across-the-lifespan/stress-and-anxiety/articles/2012/stress-the-role-of-glucocorticoids/">wake-up signal</a>, turning on our appetite and energy. </p>
<p>When we travel <a href="http://www.brainfacts.org/across-the-lifespan/stress-and-anxiety/articles/2012/stress-the-role-of-glucocorticoids/">long distances</a> our body’s sleep-wake cycle takes a while to adjust. So increased cortisol levels and hunger may occur at inappropriate times of the day.</p>
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<h2>For women, changes in sex hormones affect sleep</h2>
<p>The relationship between hormones and the sleep-wake cycle in women is further influenced by the <a href="http://www.hindawi.com/journals/ije/2010/259345/">menstrual cycle</a>. Just before a woman’s period, hormonal changes, including the sudden drop in levels of <a href="http://www.yourhormones.info/Hormones/Progesterone.aspx">progesterone</a>, affect the body’s temperature control, which in turn can reduce the amount of “REM” sleep. This is the stage of sleep when most of our dreams occur. </p>
<p>For women with <a href="http://www.hindawi.com/journals/ije/2010/259345/">severe premenstrual symptoms</a> reduced levels of melatonin before bedtime just before their menstrual period can cause poor sleep, including night-time awakenings or daytime sleepiness.</p>
<p>Changes in hormone levels also contribute to sleeping difficulties during <a href="http://sleepfoundation.org/sleep-topics/pregnancy-and-sleep">pregnancy</a>. Increased progesterone levels can cause daytime sleepiness, particularly in the first trimester. High levels of <a href="https://theconversation.com/the-brain-also-produces-the-sex-hormone-oestrogen-21194">oestrogen</a> and progesterone during pregnancy can also cause nasal swelling and lead to snoring.</p>
<p>During <a href="http://www.sleephealthfoundation.org.au/fact-sheets-a-z/212-menopause-and-sleep.html">menopause</a>, low levels of oestrogen may contribute to sleeping difficulties. Changes in hormone levels mean that body temperature is less stable and there may be increases in adrenaline levels, both of which can affect sleep. </p>
<p>The loss of oestrogen causes body fat to move more to the stomach area, which increases the chances of women having snoring and <a href="https://theconversation.com/health-check-heres-what-you-need-to-know-about-sleep-apnoea-26402">sleep apnoea</a>.</p>
<h2>For men, testosterone levels affect sleep</h2>
<p>For men, levels of <a href="http://www.ncbi.nlm.nih.gov/pubmed/24435056">testosterone</a> are highest during sleep and require at least three hours sleep to reach this peak. Low levels of testosterone in men, which can occur with sleep deprivation, ageing and physical problems, have been associated with a reduction in sleep efficiency and changes to the stages of sleep men experience. </p>
<p>Testosterone can be taken as a <a href="http://www.smrv-journal.com/article/S1087-0792(07)00166-9/">drug</a> but abuse of it can lead to other sleep problems.</p>
<h2>Hormones influence our dreams</h2>
<p>Finally, as we sleep, our hormones, including levels of <a href="https://www.psychologytoday.com/blog/dream-catcher/201108/oxytocin-sleep-and-dreams">oxytocin</a> and <a href="http://www.ncbi.nlm.nih.gov/pubmed/15576884">cortisol</a>, may influence the content of our dreams.</p>
<p>By doing things to promote good sleep, such as reducing stress, engaging in relaxing evening routines before bed, going to bed and getting up at regular times, or seeking professional help for sleeping difficulties, we can facilitate the replenishing activities of our hormones that help us make the most of our day and optimise our well-being.</p>
<p><em>This article is part of an occasional series, <a href="https://theconversation.com/au/topics/chemical-messengers">Chemical Messengers</a>, on hormones and the body. Stay tuned for other articles on hunger, mood and sexual desire.</em></p><img src="https://counter.theconversation.com/content/44983/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jo Abbott 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 allows many of our hormones to replenish so we have the optimal energy, immunity, appetite and coping ability to face the day’s highs and lows.Jo Abbott, Research Fellow / Health Psychologist, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.