ABERRANT TEMPORAL PATTERNING OF SLOW-WAVE SLEEP IN SIBLINGS OF SIDS VICTIMS

We assessed the patterning of slow-wave EEG activity during sleep in s iblings of sudden infant death syndrome (SIDS) victims over the first 6 months of life. Twelve hour overnight physiologic recordings were ob tained from 25 apparently healthy subsequent siblings of SIDS victims and 25 control infants at 1 week, and 1, 2, 3, 4 and 6 months of age. The EEG activity was electronically bandpass filtered, leaving primari ly activity ranging from 0.5 to 2.5 Hz (the delta frequency), and the filtered traces were full-wave rectified and integrated over 1 min per iods. The recordings were divided into four 3 h segments beginning at sleep onset, and the mean integrated delta activity during quiet sleep was determined for each segment of the night. At 3 and 4 months postn atal age, SIDS siblings displayed increased integrated delta amplitude in the early morning hours relative to control infants. Most SIDS dea ths occur in the early morning hours during the 2-4 month age range. W e thus speculate that increased delta activity may be indicative of in creased arousal thresholds in the early morning, which may contribute to SIDS deaths.