title: Human non-24-hour sleep-wake cycles in an everyday environment.
abstract: A sighted college student maintained a sleep-wake cycle longer than 24 hr in his everyday environment for more than half of nearly four years. The range of sleep-wake periods and the amount and regularity of sleep are consistent with those found in time-free environments. Episodes of 24 hr periodicity suggest that social cues or obligations are effective entraining agents. He reported more sleep difficulties while on a 24 hr than a non-24-hr schedule.
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D003463:Cues; D005260:Female; D006801:Humans; D008297:Male; D010507:Periodicity; D005082:Physical Exertion; D012894:Sleep Stages; D012931:Social Environment; D014851:Wakefulness