brain scans

A drop in activity in our right hemisphere would promote emotions related to anger, both awake or sleeping.

Do you remember what you dreamt of last night?

Was your dream full of negative emotions, tinged with rage? If so, it may well be that your prefrontal cortex’s right side is responsible.

By identifying the brain activity of seventeen healthy adults (ten women and seven men) during sleep, Finnish, Swedish and British scientists identified a marker that would explain why some people are more prone to have bad dreams during the night.

The study, published in the Journal of Neuroscience, claims that less activity in the right hemisphere of the brain would promote feelings of anger when alert – which had already been pointed out in previous work – but also during sleep.

This imbalance is known as alpha frontal asymmetry. The right area of ​​the frontal lobe has been shown to be involved in regulating emotions, according to researchers at the University of Turku, Finland, who authored the study. Less activity in this area, which is characterized by large oscillations of the alpha waves, indicates that these people may be less able to control their anger, including in dreams.


This neural signature was identified by electroencephalogram recordings made during two nights spent in a sleep laboratory.

After five minutes of REM sleep – the state when dreams are most common – the participants were awakened, then invited to describe their dream and assess the emotions they had experienced. The operation was then repeated throughout the night.

Conclusion: in 41% of the dreams reported, the participants declared that they felt angry.

And their brain activity betrayed the same thing. The study shows that there is a similar mechanism at work in different states of consciousness. Experts do not exclude, in the long term, from using brain stimulation techniques in order to modulate the activity of the right part of the prefrontal cortex in people with alpha frontal asymmetry, and to see if this modifies the nature of the emotions in their dreams.

If it needs to be replicated on a larger scale in order to consolidate the results, this study provides additional proof that dreams are not a pure invention of the brain upon waking.

Some people still support this theory, according to a doctor at the Center for Investigation and Research on Sleep at the CHUV, in Lausanne (Switzerland). This study suggests that we can trust the reports of dreams delivered by people who have lived them and that there is even a neural correlate, a kind of objective imprint of these.

Regulation of emotions

Sometimes extremely unpleasant, the sensations experienced in dreams could also, in some cases, have a function of regulating emotions. They would allow us to better prepare ourselves to face anxiety-provoking or dangerous situations that may arise in real life.

This has been shown in a forthcoming study, carried out in particular in the Department of Fundamental Neurosciences at the University of Geneva.

This conviction has existed for a long time, but the experimental evidence was lacking.

To prove this, they first identified the regions of the brain activated when fear is experienced in dreams, namely the islet, the amygdala and the anterior cingulate cortex.

Subsequently, they tested 89 awakening participants by presenting them with frightening images and found that these same regions were less active in individuals whose incidence of fear-related dreams was higher. Thus, the latter reacted in a less excessive manner and more adapted to the distressing situations.

Negative experiences of sleep could therefore help the neuroscience community.

As proof: according to observations made by neurologists, the medical students who had dreamed the most of their upcoming competition – even imagining the worst scenarios – had, in the end, been the most successful. Something to put into perspective the next time you dream of missing an exam or an important presentation.