Sex differences in the maturation of sleep/wake patterns in high risk for SIDS infants.

Male and female high risk for SIDS infants were compared with a group of rigorously matched controls in sleep/wake variables during the peak period for SIDS, i.e., 2-4 mos. Continuous 24-72 hr. in-hospital recordings yielded data based on 3,792 hrs. of electrophysiological activity. The data show that risk male infants fail to demonstrate an increase in wakefulness with age and reveal a lag in the maturation of REM sleep compared to controls and female risk infants during the critical age for SIDS. Significant sex differences within the first six months of life are of particular importance because of the consistently reported higher incidence of SIDS in males than females. An immature sleep/wake organization which occurs differentially in male high risk for SIDS infants suggests that a CNS functional disorder is present selectively in male infants as a precursor to SIDS. The greater susceptibility of male infants to SIDS emphasizes the importance of these data based on unique long-term recordings.