Ontogeny of sleep and awake states in relation to breathing in preterm infants.

This review will focus on the development of behavioural states and breathing during early developmental stages prior to term gestation. Although these behavioural states are immature during early development, their cyclicity is clearly seen. Preterm infants characteristically have a large proportion of indeterminate sleep and small amount of wakefulness. Whereas oxygenation is relatively stable during active and quiet sleep in ventilated preterm infants, indeterminate sleep and arousals are associated with hypoxaemic episodes. Arousals have also been linked to apnoea in spontaneously breathing infants. Since well-defined sleep cycles are beneficial for the oxygenation of preterm infants, we should explore ways to promote their natural sleep while they are exposed to neonatal intensive care. Care practices such as clustering procedures, kangaroo care and optimal positioning have been shown to improve the integrity of sleep. Optimizing the sleep cycling might improve the long-term outcome of preterm infants. More studies in this area are clearly needed.