Abstract □ 161

The cardiorespiratory control system undergoes functional maturation after birth. Until this process is completed, the cardiorespiratory system is unstable, placing infants at risk for cardiorespiratory disturbances, especially during sleep. The effects of rapid-eye-movement (REM) sleep on various mechanisms involved in cardiorespiratory control are of particular significance during the postnatal period since newborns spend much of their time in this sleep state. Since respiratory and cardiac disturbances are known to occur selectively during REM sleep, the predominance of REM sleep may be a risk factor for abnormal sleep-related events during early infancy. Cardiorespiratory control changes with postnatal age, as a result of maturation of the respiratory centers, the mechanics of the respiratory pump including upper airway mechanics, the changes in metabolic demands, and the maturation of the autonomic nervous system controlling heart rate and heart rate variability. During the developmental period of the first months of life, the infant is vulnerable and limited for the adaptation to stress and the maintenance of homeostasis. Prenatal events may increase the vulnerability of the developing infant. Furthermore, intrinsic vulnerability may predispose to early disturbances of the cardiorespiratory control. Awareness of the developmental changes in cardiorespiratory adaptation during sleep is important for clinicians dealing with problems such as apparent life-threatening events, sudden infant death, and/or cardiorespiratory responses to respiratory disorders such as chronic lung disease.