Is SIDS associated with sleep? : A report of six cases demonstrating difficulty in this determination.

Epidemiological studies suggest an important association of sudden infant death syndrome (SIDS) with sleep. Because these deaths are very rarely observed, this association is difficult to confirm. When nearby caretakers hear noises suggesting that some infants are awake before their deaths from SIDS, this determination may be even more difficult. We report six cases illustrating the difficulty in determining the sleep status of SIDS infants immediately prior to their deaths. A retrospective analysis was undertaken of the San Diego SIDS/SUDC Research Project database and the new SIDS definition proposed at the January 2004 conference in San Diego, California was applied. The circumstances surrounding the deaths of six infants led nearby caretakers to speculate that all were awake before dying. However, careful analyses suggest that all but one infant were actually sleeping before their deaths. This study strengthens the association of SIDS with sleep and emphasizes the importance of very detailed evaluation of the circumstances of death in all cases of sudden infant death. The use of the recently stratified definition for SIDS as well as the new category of unclassified sudden infant death (USID) is recommended.