Implications for practice and research: Extreme cardiorespiratory events can be documented during sleep and are more common in immature preterm infants. The supine sleep position does not appear to decrease the risk of Sudden Infant Death Syndrome (SIDS) by decreasing the risk of extreme cardiorespiratory events in vulnerable infants. Reasons for the physiological advantage of the supine sleep position remain speculative and require ongoing study despite decreases in SIDS death rates in recent years.