Enforced 24-hour recovery following sleep deprivation.

The pattern of recovery sleep after sleep deprivation was investigated in healthy young adults. Six subjects experienced three experimental conditions (0, 24, and 48 hr sleep deprivation) in a Latin Square design. The recovery period consisted of a 24-hr enforced time in bed during which subjects were polysomnographically recorded beginning at 0800. To assess the differential effects of the deprivation conditions, the total sleep time on the 24-hr recordings was submitted to a six (4-hr block) by three (deprivation condition) multivariate analysis of variance. Subjects slept more following the 24- and 48-hr conditions when compared to the 0-hr condition. Across conditions, subjects slept more during the first 4 hr when compared to the remaining five blocks. Importantly, there was a significant interaction of sleep deprivation by 4-hr block. In block 1 sleep was differentially recovered between each condition with more sleep being recorded following longer hours of deprivation. In block 2 subjects in the 24- and 48-hr conditions slept comparable amounts and significantly more than those in the 0-hr condition. In blocks 3 and 4 only the 48-hr condition exhibited significantly more sleep than the 0-hr condition. However, significantly less sleep was found in block 6 following the 48-hr condition. Overall, subjects recovered 72% and 42% of the total amount of sleep lost during the 24- and 48-hr conditions, respectively.