We transition between at least 19 different brain phases when sleeping, study

New knowledge about brain activity while we sleep.


Before the 1950s, scientists used to believe that as people drifted off to sleep, their brains and bodies would go into shutdown mode, entering a passive state that allowed them to recover from the previous day. Researchers have since learned that sleep is a lot more complicated, and it’s a much more active state than you might think. While you’re getting your zzz’s, your brain goes through various activity patterns.

A new study from Aarhus University has now indicated that we transition between 19 different brain phases when sleeping. Scientists have uncovered, for the first time, the large-scale brain patterns and networks in the brain that control sleep, providing knowledge that, in the future, may, in the long term, help the many Danes large proportion of people who experience problems sleeping.

The study conducted in collaboration with the University of Oxford offers new insight into the patterns and networks used by the brain during sleep. For this, scientists used an fMRI method with algorithms that can identify brain activity patterns.

Angus Stevner, a postdoc at the Center for Music in the Brain at Aarhus University, said, “This provides a new and potentially revolutionary understanding of brain activity during sleep, which can, in turn, lead to new forms of treatment of the sleep problems that affect far too many people.”

“Our results can change the way in which we understand sleep and, not least, the way we look at sleep disorders such as insomnia. We hope to be able to utilize this new and detailed categorization of sleep to identify changes in the brain activity of people suffering from certain with unexplained sleep disorders, such as dyssomnia or insomnia, which we currently cannot explain.”

Usually, sleep is considered to be passed through 4 stages: 1, 2, 3, and REM (rapid eye movement) sleep. These stages progress cyclically from 1 through REM, then begin again with stage 1. All these stages were believed to produce different brain waves due to the brain’s electrical activity.

Angus Stevner said, “This way of dividing sleep into stages is really based on historical conventions, many of which date back ing from to the 1930s. We’ve come up with a more precise and detailed description of sleep as a higher number of brain networks which change their communication patterns and dynamic characteristics during sleep.”

“At the moment we lack a consistent understanding of what’s happening in the brain of someone suffering from insomnia, but also of the role sleep has in mental disorders, where sleep disorders are all-pervadingextremely common,” says the researcher.

In recent years, progress made in modern brain scanning techniques has led to a far more nuanced understanding of the brain’s complexity, which the traditional sleep stages do not take into account.

“Our results provide a modern description of human sleep as a function of the brain’s complex network activities and we’re trying to move on from the somewhat simplified picture that has thus far characterized our understanding of brain activity during sleep,” he says.

Journal Reference

  1. Stevner, A.B.A., Vidaurre, D., Cabral, J. et al. Discovery of key whole-brain transitions and dynamics during human wakefulness and non-REM sleep. Nature Communications 10, 1035 (2019). DOI: 10.1038/s41467-019-08934-3
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