Stage 4 Sleep: Influence of Time Course Variables

Science  24 Dec 1971:
Vol. 174, Issue 4016, pp. 1354-1356
DOI: 10.1126/science.174.4016.1354


Age, length of prior wakefulness, length of time asleep, and a circadian influence all affect stage 4 sleep. The amount of stage 4 sleep decreases as subject's age increases and as time asleep increases. Longer periods of wakefulness before sleep result in greater amounts of stage 4 sleep in the first 3 hours of sleep. Sleep periods that begin at times other than the regular onset time tend to produce less stage 4 sleep; this decrease suggests a circadian effect.