SLEEP CYCLE CHARACTERISTICS IN INFANTS

Abstract

Within the sleep of adults and infants there are cyclic fluctuations between quiet and active sleep. These fluctuations may also persist during wakefulness as rest-activity cycles but are less readily detected. They constitute a fundamental biological rhythm on which other daily rhythms are superimposed. In adults the rest-activity cycle is 90 minutes in duration. The quiet-active sleep cycles of term, 3-, and 8-month-old infants were determined by polygraphic recording of eye and body movements, respirations, and electroencephalogram. The cycle length at term was 47 minutes and 49 and 50 minutes at 3 and 8 months. The increase in cycle length with maturation was not significant, but there was a significant change in the proportion of quiet to active sleep within a cycle. At term they were equal, while at 8 months quiet sleep was twice as long as active sleep. Quiet sleep is a highly controlled state requiring complex feedback mechanisms. The increasing proportion of quiet sleep may be a significant measure of normal brain development.