Researchers have found that vivid, immersive dreams can make sleep feel deeper and more restorative, even during periods of high brain activity. A study analyzing brain recordings from 44 healthy adults showed that participants reported their deepest sleep after intense dream experiences. The findings challenge traditional views of deep sleep as minimal brain activity.
Scientists at the IMT School for Advanced Studies Lucca analyzed 196 overnight EEG recordings from 44 healthy adults as part of a European Research Council-funded project on sensory stimulation and sleep perception. Over four nights in a lab, participants were awakened more than 1,000 times to report their experiences and rate sleep depth and sleepiness levels just before waking. High-density electroencephalography tracked brain activity throughout. The results revealed that reports of deep sleep occurred not only during periods without conscious experience but also following vivid, immersive dreams, typically associated with REM sleep where brain activity resembles wakefulness. In contrast, shallow sleep correlated with fragmented or vague mental experiences lacking clear content. Giulio Bernardi, professor of neuroscience at the IMT School and senior author, explained: 'In other words, not all mental activity during sleep feels the same: the quality of the experience, especially how immersive it is, appears to be crucial.' He added that immersive dreams may reshape how sleepers interpret brain activity, making sleep feel deeper. As the night progressed, physiological sleep pressure decreased, yet participants perceived their sleep as deepening, mirroring an increase in dream immersiveness. This suggests dreams help maintain a sense of restorative sleep by buffering brain fluctuations and preserving separation from the external world. Bernardi noted: 'Understanding how dreams contribute to the feeling of deep sleep opens new perspectives on sleep health and mental well-being.' The study, conducted in collaboration with Scuola Superiore Sant'Anna in Pisa and Fondazione Gabriele Monasterio, appears in PLOS Biology (DOI: 10.1371/journal.pbio.3003683). Authors include Adriana Michalak and others.