Timing of REM and stages 3 + 4 sleep during temporal isolation in man

Abstract

During nonentrained sleep-wake conditions in man, healthy adult subjects spontaneously develop 'long' biological days (>35 hr) in addition to the normal, approximately 25 hr day. The ratio of sleep to total time remains constant (approximately 0.30), with long sleep episodes occurring approximately 180° out of phase with the short sleep episodes. The timing and amount of REM sleep advance to an earlier time within the sleep episode during free-running, whereas stage 3+4 sleep is related to the initiation and course of the sleep process itself. The REM-NREM cycle length does not change, comparing entrained and nonentrained conditions. The study of the chronophysiology of humans under nonentrained conditions may serve as a model of the chronopathology of sleep-wake changes which occur in sleep disorders associated with depression, narcolepsy-cataplexy, sleep-wake dyssomnias, delayed sleep phase insomnia, and aging.