Nocturnal sleep organization in infants "at risk" for sudden infant death syndrome.

Nocturnal sleep organization was compared in normal infants and those "at risk" for sudden infant death syndrome (SIDS) (siblings and near-miss infants). Before 12 weeks of age, sleep modifications were observed in "at risk" infants. During their sleep they had a smaller percentage of intervening wakefulness with a higher amount of active sleep. Quiet and active sleep episodes had longer durations resulting in a longer sleep cycle. After 12 weeks, sleep organization tended to normalize. This fact is discussed as a possible factor for a SIDS event: a higher arousal threshold could play a critical role if homeostasy is disturbed during sleep, mainly at an age when the homeostatic control is not fully established.