Local sleep episodes while awake
Adequate sleep quantity and intensity is required to oversee brain plasticity which in turn controls vigilance, cognitive and learning processes . Sleep is regulated by two oscillatory processes. The circadian process oscillates on a near 24 hours
and defines the sleep inclination periods . Most of the time, the circadian process is synchronized with the light/dark cycle. Regulated separately but in concomitance with the circadian process, the homeostatic process, represented
by sleep pressure, builds up with the time spent awake. High sleep pressure markers can be observed during wakefulness, by a reinforcement of theta activity (5-8Hz), and while asleep, by an increase of delta activity (0.5-4Hz),
also called slow wave sleep .
Slow wave sleep is thought to be the time when neurons perform cellular maintenance . Recently, it has been shown that similar local sleep episodes can be observed in awake rodents . Using scalp electroencephalography (EEG), local sleep episodes have also been studied in awake humans after a period of sleep deprivation .
Experimental evidence indicates that astronauts tend to experience sleep deficiency on board of the international space station (ISS), at least until their circadian clock is realigned with the new environment . The aim of our project is to understand how sleep deficiency reported by most astronauts in space impacts local sleep episodes.