Sleep studies on a 90-minute day.

After 2 adaptation and 2 baseline all-night sleep recordings, 5 normal young adult subjects (3 males) were placed on a schedule alternating 60 min of wakefulness and 30 min of sleep for 5 1/3 24-h periods. A 2-day recovery period followed. One male subject (MA15) was later placed on the identical protocol with the exception that he was allotted periods of 75 min of wakefulness and 15 min of sleep during the experimental period. One male narcolepsy-cataplexy patient was placed on the 60-30 schedule for 48 h. All subjects showed REM sleep during the schedule manipulation. REMM sleep occurred within 10 min of sleep onset (SOREMP) on 79 of 110 REM sleep occasions in the normals, on all 29 REM episodes in MA15, and on 16 of 17 REM periods in the narcoleptic. In the normals, REM sleep showed a tendency to recur on alternate 90-min cycles, while in the narcoleptic REM recurred on consecutive periods. Compared to baseline, REM sleep 24 h was decreased in the normals and increased in the narcoleptic. Time spent in slow wave sleep and stage 2 was also reduced in the normal subjects on the 90-min schedule, and stage 1 sleep time was increased. Peak sleep times for the 5 normals occurred between 09.00 and 12.30 and lowest sleep times from 21.00 to 02.00. During the first recovery night, sleep times ranged from 11.5 to 18.5 h, including significant increases of slow wave sleep and REM sleep. Except for SOREMPs, no signs of the narcolepsy-cataplexy syndrome were seen in any of the normal subjects.