Temporal distribution of sleep states, somatic activity, and autonomic activity during the first half year of life.

Twelve-hour, all-night polygraphic recordings were obtained from 25 normal infants at 1 week and 1, 2, 3, 4, and 6 months of age. The objectives of the study were to provide a description of the emerging temporal distribution of quiet sleep (QS), active sleep (AS), and motility, and to describe the maturation of a circadian influence upon heart rates. With increasing age, increased percentages of AS began to cluster toward the end of the night and increased percentages of QS toward the beginning. A circadian influence upon heart rates was observed in AS and indeterminate sleep prior to its existence in QS. At 2 and 3 months of age motility in AS and QS increased linearly during the night.