Dream-like mental states can occur during wakefulness

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.