P064 Process O May Contribute to the 90 min NREM/REM Sleep Cycles

Abstract The mechanism responsible for the ubiquitous NREM/REM sleep cycles of approximately 90-min period length in humans remains largely unknown. It was originally said to be a product 90-minute Basic-Rest-Activity-Cycle (BRAC) assumed pervade throughout and wakefulness. However, evidence existence BRAC during wakefulness is weak questionable. important consider other possible contributors this fundamental cycle process. Process O (state onset, offset) has been suggested account empirical data inexplicable by Processes S C. question significant increase alertness following brief nap (<10min sleep) longer than predicted episodes (40-90 min) awakening towards end normal period. proposed operate similarly but with build-up inhibition an ongoing state (wake or NREM REM that rapid self-limiting after 1-2 hours. also (~10min) dissipation previous offset such resuming (onset) rejuvenates functions (wakefulness, NREM, sleep). In operation accumulates over first 80-100 minutes enough flip ‘sleep switch’ another (REM Only (5-10min) needed dissipate still stronger REM, can resume cycle.