Sleep parameters and respiratory variables in "near miss' sudden infant death syndrome infants.

Twenty-nine near miss for sudden infant death syndrome and thirty normal infants between the ages of 3 weeks and 6 months were monitored polygraphically for 24 hours. The distribution of sleep and abnormal respiratory events were analyzed for both groups. On the basis of mixed and obstructive apnea, 12-hour nocturnal segments (8 PM to 8 AM) consistently distinguished near miss from normal infant groups between the ages of 3 weeks and 4.5 months. Daytime naps do not provide statistical differences sufficient to differentiate between the two groups. During sleep, abnormal respiratory events are more likely to occur between 1 AM and 6 AM, at least 40 minutes after sleep onset. Respiratory pauses show a significant increase just prior to waking (a strong respiratory stimulus). Any impairment of the arousal threshold during sleep will place near miss infants at increased risk.