Peculiarities of human sleep in the case of double alternation of "sleep-waking" cycles.

The dynamics of sleep was studied in seven healthy subjects in two schedules, differing in the magnitude of the sleep intervals and their distribution over the 24 hour period. The first series provided for the use of two four-hour sleep intervals, the second six- and two-hour intervals. The investigations showed that the transition to a new schedule was accompanied by substantial qualitative and quantitative sleep disturbances, followed by a restoration of sleep as the subjects adapted. Less pronounced sleep disorders and more rapid restoration were observed in the schedule with nonuniform distribution of the intervals; more pronounced sleep disorders and a slowed restoration of sleep were observed on the schedule with two four-hour intervals.