An international consortium of researchers has created the largest-ever database compiling records of brain activity during sleep and dream reports. One of the first analyses of the database confirmed that dreams do not occur only during REM sleep, but also during deeper and calmer NREM stages. In these cases, brain activity resembles wakefulness more than deep sleep, as if the brain were "partially awake".
One third of a healthy adult's life is spent sleeping, and a significant portion of that time is spent dreaming. Throughout the night, during any sleep stage, subjective conscious experiences, what we call dreams, can repeatedly occur.
Interest in dreams dates back thousands of years, from ancient Egypt to ancient Mesopotamia and ancient Greece, and spans many cultures and traditions. While dreams have long fascinated the public, their study holds substantial scientific value, supporting various research areas, including clinical topics (such as parasomnias, like sleepwalking), neurocognitive domains (such as learning and memory), and the basic ones (like the neural correlates of consciousness).
Numerous studies have explored what happens in the human brain during dreaming, contributing to major advances in the scientific exploration of human consciousness. However, until now, there had never been a comprehensive integration of data that would allow for broad analysis of findings.
In this context, an international consortium of researchers, including Giulio Bernardi (IMT School for Advanced Studies Lucca, Italy), supported by the Bial Foundation, created DREAM - Dream EEG and Mentation, the largest database ever assembled that combines recordings of brain activity during sleep with dream reports. This unique collection enables the study of dreams on an unprecedented scale and with rigorous analysis, addressing one of the field's biggest challenges: the lack of comparable and accessible large data samples.
Bringing together multicentred records of electroencephalography (EEG), magnetoencephalography (MEG), and dream reports, DREAM includes over 2,600 awakenings from 505 participants across 20 different studies. It is freely available at monash.edu/dream-database and welcomes contributions from laboratories worldwide.
In the article A dream EEG and mentation database , published in the scientific journal Nature Communications, the authors present DREAM and the first analyses of the database, which revealed surprising results: dreams are not exclusive to REM sleep (the phase where the brain is most active and the eyes move rapidly), but also happen during NREM sleep, in its deeper and calmer stages. Interestingly, when dreams occur in NREM, brain activity resembles wakefulness more than deep sleep, as if the brain were "partially awake".
Moreover, the researchers applied artificial intelligence algorithms to analyse brain activity patterns before each awakening. Using these data, they were able to predict whether the person was dreaming at that moment, with consistent results. This innovative approach could, in the future, allow for more precise identification not only when we are dreaming, but also the kind of experience we are having during sleep.
Giulio Bernardi recalls that "the work presented in the article, coordinated by Monash University (Australia), resulted from the efforts of 53 authors from 37 institutions across 13 countries, and represents a decisive step in the scientific exploration of human consciousness by bringing together and making decades of dream research available in one place".
Learn more about the project "91/20 - Mentation report analysis across distinct states of consciousness: A linguistic approach" here .
