DISTRIBUTION OF SLOW-WAVE EEG ACTIVITY ACROSS THE NIGHT IN DEVELOPINGINFANTS

Adults show distinctive patterns of slow-wave (delta) electroencephalo gram (EEG) activity across each sleep cycle and across the night. We e xamined the ontogeny of slow-wave EEG patterning in infants. Twelve-ho ur overnight physiological recordings were obtained from 25 normal inf ants at 1 week and 1, 2, 3, 4 and 6 months of age. The EEG activity wa s band-pass filtered, leaving primarily activity ranging from 0.5 to 2 .5 Hz (the delta frequency). Filtered EEG traces were full-wave rectif ied and integrated over 1-minute periods. Nighttime recordings were di vided into four 3-hour segments, beginning at sleep onset, and the mea n integrated delta activity during quiet sleep was determined for each segment of the night. In addition, patterns of delta activity across extended periods of quiet sleep (15 minutes or longer) were determined . Beginning at 2 months of age, integrated delta activity declined sig nificantly over the night. Moreover, beginning at 3 months of age, del ta activity increased significantly over individual periods of quiet s leep; in neonates up to 1 month of age, delta activity decreased signi ficantly within epochs of quiet sleep. Beginning at 2-3 months of age, infants show patterns of delta activity similar to those found in adu lts.