Sleep organization in children at risk for sudden infant death syndrome.

The organization of sleep was studied in four groups of 6-month-old babies: monitored near-miss babies (NM), monitored siblings (HR), nonmonitored siblings (LR), and siblings considered at low risk but monitored because of marked parental anxiety (PA). It was studied using the method of cumulated occurrences and orthogonal polynomial fitting introduced for the analysis of sleep by Gaillard and Martinoli in 1976. No monitoring effect was found. We also found no difference between the groups when the usual sleep scores were used. However, differences were found with the polynomial adjustment method: there was more quiet sleep stage 3 in NM than in any other group. There was less waking state and more paradoxical sleep at the end of the night in PA and NM than in HR or LR babies. This suggests that the differences may not be related so much to real risk as to parental comportment.