Aging, Sleep, Cognitive Process

The aim of the study is to determine the impact of aging, circadian rhythms and sleep deprivation on executive performances. Volunteers will complete a 40-hour extended wakefulness period in constant condition (semi-recumbent posture in bed, constant dim light levels \< 10 lux, food and liquid intake at regular intervals) in order to control the circadian system. The volunteers will not be allowed to sleep in the sleep deprivation protocol ("high sleep pressure protocol") and will adopt a short wakefulness/sleep cycle (150/75 minutes) in the multiple nap protocol ("low sleep pressure protocol"). Tests and scales will be repeated every 3H45