Chronotype and general tendency to daydream in daily life will be evaluated at the inclusion visit. Healthy volunteers will be placed in sleep deprivation patterns that will modify the level of secondary hypersomnolence. These patterns correspond to sleep deprivation caused by work schedules usually observed: shift work (SDP1) or night on-call (SDP2). shift work will be simulated by total sleep deprivation for 24 hours (comparable to the first day of a night worker) followed by early morning sleep, and an extended 17 hours wakefulness (comparable to second day of night shift). Secondary hypersomnolence will be assessed throughout prolonged awakenings (24 hours + 17 hours). The night on-call will be simulated by two half-hour awakenings during the nocturnal sleep. Hypersomnolence will be measured within 17 hours of wakefulness following this sleep fragmentation. The sleep history (quantity and quality of sleep) will be evaluated by actigraphy + ambulatory polysomnography (1 day before the experiment) and 2 polysomnographies in the laboratory during the experiment. Polysomnography recordings will be visually and automatically analyzed by the ASEEGA algorithm. Ambulatory recordings are automatically analyzed by ASEEGA. Throughout these sleep deprivation patterns, electrophysiological variables (EEG, EOG and EMG) will be continuously recorded in order to identify objective drowsiness states determined visually using the OSS or automatically by the MEEGAWAKE algorithm. Subjective sleepiness scale, Mind wandering scale, maintenance of wakefulness tests (MWT, electrophysiological test) and cognitive tests will be repeated, every 4hr, throughout the sleep deprivation patterns in order to determine abilities to stay awake, driving performance, sustained and selective attention, vigilance.
The objective of this clinical study is to develop solutions for the evaluation and management of drowsiness, based on 2 EEG sensors only, aiming at reducing the risk of accidents related to secondary hypersomnolence (sleepiness induced by sleep restriction or abnormal sleep/wake cycle). This project will allow a better understanding of the determinants of drowsiness and its impact on cognitive performance and the development of methods and models for the evaluation and prediction of cognitive performance deficit related to sleepiness. The secondary hypersomnolence will be objectified by continuous EEG recording and analysed by visual reading according to Objective Sleepiness Scale (OSS) criteria and automatically analyzed using the MEEGAWAKE algorithm (developed by PHYSIP). The level of secondary hypersomnolence will be modified by varying the duration and maintening of prior sleep or the sleep timing. The ability to stay awake will be measured by the maintenance of wakefulness test (MWT). Subjective sleepiness and mind wandering will be measured before and/or after all measurements. Simulated driving task, maintenance of wakefulness tests and several cognitive tasks to measure sustained attention, alertness, selective attention will be performed every 4 hours.