Development of sleep in infancy.

siol. 2 I (4) : I 243-1246. 1 g66.-Seven children were repeatedly observed, up to 6 months of age, during nighttime and after-noon sessions. Using criteria of respiration, ocular reactions, motor activity, vocalization, hand movements with toys and EEG, the state of quiet sleep, the state of active sleep, and the waking state have been distinguished. Quiet sleep (regular breathing with frequency of 3o/min, closed eyes without move-ments, disappearance of body movements, spindles and slow waves in EEG) alternated with active sleep (irregular respira-tion, eyes alternatively closed, half-open or there were move-ments of bulbus oculi, increased frequency of body movements) in about 50- to 6o-min intervals. The individual periods of quiet sleep lengthened with age to approximately 22 min on the average. The total duration of quiet sleep increased signifi-cantly with age from 16.77 ~ in the 2nd week to ~4.87 ~ in the 24th week. The most striking changes took place in the first I 2 weeks of life. respiration; motor activity; sleep cycles T HANKS TO intensive neurophysiological studies of sleep carried out in recent years, our knowledge of sleep in man is becoming more precise. Two states have been distinguished, a state characterized by rapid eye move-ments, irregular respiration and pulse rate and a state characterized by the absence of eye movements, regular breathing, low respiratory frequency and low pulse, with spindles and high-voltage slow activities in the EEG. Attention has been paid to the state of rapid eye move-ments and its importance (2, IO). However, the nature of the different states of sleep has not been fully explained even though these problems have been studied inten-sively both in humans and animals. In this report, sleep and its development in infants will be described. Seven infants were studied repeatedly from the 2nd week of life to the age of 6 months. This is a period of very rapid development of the central nervous system. The infants were observed during night sleep because it begins to prevail over day sleep soon after birth (9) and is less interrupted by outside stimuli (by feeding, etc.), which can influence it in various ways. Received for publication 23 August 1965.