Immersive NREM2 dreaming preserves subjective sleep depth against declining sleep pressure.
Adriana Michalak, Davide Marzoli, Francesco Pietrogiacomi, Damiana Bergamo, Valentina Elce, Bianca Pedreschi, Giorgia Mosca, Alessandro Navari, Michele Emdin, Emiliano Ricciardi, Giacomo Handjaras, Giulio Bernardi
PLoS Biology March 1, 2026 DOI: 10.1371/journal.pbio.3003683 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Population | Healthy human participants |
| Topics | Dreaming |
| Key findings | Perceived sleep depth is not solely determined by reduced cortical activation; immersive dreaming may help sustain the subjective experience of deep sleep as homeostatic pressure wanes. |
Abstract
Perceived sleep depth is a key determinant of subjective sleep quality, traditionally thought to reflect unconsciousness and reduced cortical activation. Here, we combined high-density EEG with a serial awakening paradigm during NREM2 (N2) sleep in healthy human participants to examine its neural and experiential correlates. As expected, deeper sleep was associated with reduced cortical activation, reflected in a lower high-to-low frequency power ratio. Yet, this relationship weakened in the presence of dreaming, indicating that immersive conscious experiences may counteract the impact of cortical activation on perceived depth. Indeed, perceived sleep depth was lowest during minimal forms of awareness characterized by a mere sense of presence, and highest during immersive dreaming or deep unconsciousness. Across the night, physiological sleep pressure and subjective sleepiness declined, but perceived sleep depth rose alongside increasing dream immersiveness. These findings challenge the view that the feeling of deep sleep arises solely from reduced brain activity and suggest instead that immersive dreaming may help sustain the subjective experience of deep sleep as homeostatic pressure wanes.