Human deep sleep facilitates faster cerebrospinal fluid dynamics linked to brain oscillations for sleep homeostasis and memory

Abstract

AbstractWhile cerebrospinal fluid (CSF) dynamics during sleep have been implicated in metabolic waste reduction in animals, how CSF dynamics are driven in the human brain remains elusive. Here, by leveraging a simultaneous sparse-fMRI and polysomnography method designed specifically for acquiring deep stable sleep data, we present the first evidence of deep sleep-specific faster CSF dynamics in healthy young human participants. Slow waves and sleep spindles during slow-wave sleep and rapid eye movements and sawtooth waves during rapid eye movement (REM) sleep induce frequent low-amplitude CSF fluctuations, contributing to faster CSF dynamics during deep sleep. In contrast, arousal-related brain activities during light sleep produced infrequent large CSF changes. Furthermore, these brain oscillations during light and deep sleep recruited essentially different brain networks, with deep sleep emphasizing memory and homeostatic circuits. Thus, human deep sleep has a unique way of enabling faster CSF dynamics that are distinctive from arousal mechanisms.