Sleep apnea in infants who succumb to the sudden infant death syndrome.

Previous studies have shown the frequency of respiratory pauses to be altered in groups of infants at risk for the sudden infant death syndrome (SIDS). In this study, we assess the frequency of apneic pauses during quiet sleep and rapid eye movement sleep in control infants and infants who subsequently died of SIDS. Sleep states were identified in 12-hour physiological recordings of SIDS victims and matched control infants, and the number of respiratory pauses from 4 to 30 seconds in duration was computed for quiet sleep and rapid eye movement sleep. SIDS victims 40 to 65 days of age showed significantly fewer apneic pauses than did age-matched control infants across the two sleep states. Fewer short respiratory pauses accounted for most of the reduction in number of apneic events in the SIDS victims during both sleep states. During the first month of life, SIDS victims did not differ significantly from control neonates on this measure. The finding that this respiratory difference exists during the second month of life, just before the period of maximal risk for SIDS, but not earlier, may have implications for the etiology of SIDS deaths.