It turns out that the brain "wakes up" even in the deepest of sleeps

Thanks to an international consortium of scientists led by Giulio Bernardi from the IMT Graduate School of Advanced Studies in Lucca, Italy, and supported by the Bial Foundation, the largest ever archive of recordings of brain activity during sleep combined with dream reports has been created.

The DREAM (Dream EEG and Mentation) project collected data from more than 2,600 awakenings in 505 participants from 20 scientific studies.

This is the first large-scale attempt to combine EEG and MEG results with dream descriptions and provide researchers from around the world with access to a large and standardised dataset.

The analysis, published in Nature Communications, shows that dreams occur not only during the rapid eye movement (REM) phase of sleep, as previously thought, but also during the quiet, deep NREM phase. In this case, brain activity during dreaming in NREM resembles the waking state much more than deep sleep. In other words, the brain may be "partially awake" during these moments.

This discovery changes the usual view of how and when dreams occur. Previously, it was thought that most activity during dreams occurred during the REM phase - the period of sleep when the eyes are moving rapidly and the brain is maximally active. However, the new database proves: even in deep sleep, a person can have vivid dreams.

In addition, scientists used artificial intelligence algorithms to analyse patterns of brain activity that precede awakening. These algorithms predicted with high accuracy whether a person was dreaming at a given moment. This opens up the prospect of creating methods that allow us to determine in real time not only the fact of dreaming itself, but perhaps also its content or emotional nature.

As Giulio Bernardi notes, the study was the result of the efforts of 53 scientists from 37 scientific institutions in 13 countries. According to him, it is an important step towards a scientific understanding of human consciousness, as it allows for the first time to analyse decades of dream research in one integrated dataset.