EXTENDED SLEEP IN HUMANS IN 14 HOUR NIGHTS (LD-10 14) - RELATIONSHIP BETWEEN REM DENSITY AND SPONTANEOUS AWAKENING/

The sleep patterns of 8 normal subjects living in a winter-type photop eriod (10 h light and 14 h darkness; LD 10:14) for 4 weeks were charac terized by the presence of periods of spontaneous wakefulness alternat ing with periods of spontaneous sleep. Transitions from sleep to wakef ulness occurred much more frequently out of REM sleep than out of NREM sleep (P < 0.002). REM periods that terminated in wakefulness showed shorter REM durations (P < 0.0005) and higher REM densities (P < 0.000 5) than REM periods that did not terminate in wakefulness. The authors discuss these results in terms of a possible relationship between REM density and arousal level. The higher REM density preceding wakefulne ss and the increased number of REM periods terminating in spontaneous awakenings could reflect an enhanced level of a brain arousing process , resulting from reduced sleep pressure in the extended nights.