[Development of the sleep and autonomic nervous system control in premature and full-term newborn infants]

Abstract

Well defined periods of active (AS) and quiet sleep (QS) are detected as early as 27 weeks gestational age (w GA). Beyond 35 w GA, the amount of indeterminate sleep is reduced to < 10% and, up to the normal term, sleep is marked by the prevalence of AS. AS differs from QS by faster respiratory and heart rates, more central respiratory pauses, lower amplitude of high frequency heart rate variability (parasympathetico-dependent) and higher amplitude of low frequency heart rate variability (sympathetico-dependent). In artificially ventilated infants, breathing is more dependent on the ventilator in QS than in AS. When they reach term, compared with normal full-term newborns, infants with intra-uterine growth retardation or prematurity do not show significant differences of sleep structure, but present in both AS and QS, faster heart and respiratory rates, more respiratory pauses and less heart rate variability; however, sleep-states-related cardio-respiratory modulations appear similar.