Dream-like mental states can occur during wakefulness.
Nicolas Decat, Arthur Le Coz, Jade Sénéchal, Ilona Scellier-dekens, Hannah De Verville, Rubén Herzog, François-xavier Lejeune, Isabelle Arnulf, Thomas Andrillon, Delphine Oudiette
Cell reports April 7, 2026 Peer reviewed DOI: 10.1016/j.celrep.2026.117237 via PubMed
Summary
Mental experiences during wakefulness and sleep are not as distinct as commonly thought. Analyzing electroencephalography (EEG) from 92 participants during daytime rest, researchers collected 375 reports of mental content scored on bizarreness, fluidity, spontaneity, and wake perception. Clustering these reports revealed four distinct types of mental states. Crucially, all four types occurred across wakefulness, N1 sleep, and N2 sleep. EEG measures of spectral power, complexity, and connectivity differentiated these mental states independently of whether participants were awake or asleep. The findings indicate that the waking and sleeping brain can produce the same mental state, and that fine-grained brain dynamics shape the content of mental experiences.
Study at a glance
| Design | observational cohort |
|---|---|
| Sample size | 92 |
| Population | participants during daytime resting periods |
| Key finding | Four distinct phenomenological clusters of mental experience emerge across wakefulness, N1 sleep, and N2 sleep, and EEG features differentiate these mental states independently of wake/sleep stages. |
Abstract
A popular view holds that mental experiences uniquely differ between wakefulness and sleep, yet recent work suggests continuity across these stages. Here, we address this question by examining the wake-sleep transition, a window marked by rapid shifts in wake/sleep stages and mental experiences. We recorded electroencephalography (EEG) activity in 92 participants during two daytime resting periods. Participants reported their mental content and scored it along four subjective dimensions (bizarreness, fluidity, spontaneity, and wake perception). Clustering mental experiences (N = 375) based on these scores reveals four clusters with distinct phenomenological profiles. Strikingly, all these mental states emerge across wakefulness, N1 sleep, and N2 sleep. We identify EEG features of spectral power, complexity, and connectivity that differentiate mental states independently of wake/sleep stages. Our findings show that the waking and sleeping brain can produce the same mental state and demonstrate that fine-grained brain dynamics shape the content of mental experiences.