Sleep Efficiency for Sleep‐Wake Cycles of Varied Length

ABSTRACT This study was designed to test sleep efficiency while subjects were maintained on non‐24‐hr regimens of sleep and wakefulness. The regimens studied were 9, 12, 18, 30, and 36‐hr sleep‐wake cycles. In each regimen the ratio of.sleep to wakefulness was held constant in a 1:2 ratio, i.e. there were 2 hrs of wakefulness for each hour of scheduled sleep. The amounts of sleep obtained under each experimental regimen were less than those obtained under the baseline days or 24 hrs. The sleep losses resulted both from an increase in the latency of sleep onset and increased wakefulness after sleep unset. The primary variables which resulted in less efficient sleep were schedule differences in prior wakefulness, circadian effects on the displacement of sleep onset times, a sleep termination effect, and the frequency of occurrence of the allotted sleep periods. In the short regimens the awake time after sleep onset was strongly associated with the degree to which prior wakefulness was reduced. In the longer regimens the principal sources of awake time were extended sleep length and a sleep termination effect.