Sleep: effects of a restricted regime.

Eight young male subjects were permitted to sleep only 3 hours out of each 24 for 8 days. Electroencephalographic recordings were made during the 3-hour period of sleep. There was an increase in the amount of deep sleep (stage 4) during this period. On a recovery night, the first 6 hours revealed a significant increase in deep sleep, and beyond this period there was a sharp increase in stage 1-rapid eye movement sleep.