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Each dream has its own brain scan ‘signature’. mondi

An open book: the next chapter of ‘reading’ dreams

You may have read last week that a team of researchers has developed, for the first time, a way to detect the contents of people’s dreams. But what can we glean from this research?

During the same week that US president Barack Obama announced the US$100 million Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative to unlock the mysteries of consciousness, neuroscientists at the ATR Computational Neuroscience Laboratories in Kyoto, Japan reported images seen in sleep based solely on functional Magnetic Resonance Image (fMRI) scans of brain activity.

And while this all sounds very cool and futuristic, how can these findings be applied to clinical settings?

The groundwork

The team behind the Science study had previously developed computer algorithms that learn fMRI brain activity patterns when participants are looking at specific objects.

As shown in the video below, by decoding the fMRI scans alone, they could predict what visual stimulus the person was observing.

A visual reconstruction from real-time brain scans.

The team demonstrated that a similar technique can be applied to sleeping participants while dreaming and, as a result, can help to decode their dreams.

Sleeping on the job

How did the study unfold?

Three volunteers slept in MRI machines for three-hour sessions over the course of ten days.

As it is difficult to maintain sleep lying in a noisy MRI machine, researchers did not study lengthy, rapid eye movement (REM) sleep dreams, but investigated hypnagogic (the period just before deep sleep) imagery.

library chic

These are short, dream-like hallucinations that we remember when drifting in and out of sleep, typically during light sleep, such as during an afternoon nap on the couch.

The researchers woke subjects, asked them to report anything they had seen, then told them to go back to sleep.

After gathering approximately 200 of these verbal reports of hypnagogic imagery from each subject, individual visual components were extracted (such as “house” or “woman”) and grouped into broader categories (such as “building” or “female”).

When the participants were awake, the researchers then presented them with photos corresponding to each category and recorded the relevant fMRI activity.

The computer algorithm soon learnt the specific brain activity “signatures” with different image categories for each participant.

The researchers then applied the computer algorithm to the participant’s fMRI scans just before a second round of dream-reporting.

They were able to predict the content of the three participants’ hypnagogic imagery with an incredible 60% accuracy.

Waking up to the importance of dreaming

This research provides incredible insight into a phenomena that can be exceptionally vivid and lifelike while occurring, only to fade away into glimmers of vague impressions as we wake.

Until now, there was scientific debate as to whether dreams occurred during sleep at all, with some postulating dreams were recollections from short awakenings or even confabulations (inaccurate recollections) on awakening.

A number of theories attempt to explain why we dream in the first place, and those looking for insights into “dream symbolism” can yield tens of thousands of results with only a few keystrokes.


While dream symbolism has been considered important for centuries, and was popularised by Freud in the 1950s, research into dream contents took a back seat to the discovery of REM and non-REM sleep.

But a recent resurgence in dream interpretation has seen it suggested as a clinical tool; for instance, as a way to treat depression.

Being able to accurately dictate the sensory and emotional contents of dreams using brain scans, rather than relying solely on a person’s memory, will help this field flourish further.

Exploring the unconscious

The technique used in this study might reveal details about dreams that happened, but that we don’t remember.

The authors argued some fMRI patterns that corresponded with reported images, but also contained related but not reported items (such as a street with a car), “may indicate unreported but actual contents during sleep”.

One current debate in the field is whether we dream all night long and just lack the ability to recall the content on awakening.

Such techniques applied to REM and non-REM sleep may shed light on these fundamental issues of dreaming and our understanding of consciousness.

With this amazing research and the announcement of the new $100 million BRAIN Initiative in the US, very exciting possibilities lay ahead.

But rest assured: this is still quite far from putting your dreams up on a screen, so your nocturnal visions will remain private - for the time being anyway.

Further reading:
Explainer: what is dreaming?

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