Arterial oxygen tension during active and quiet sleep in the normal neonate.

The effect of sleep state on arterial oxygen tension was determined in ten healthy term infants by means of continuous transcutaneous PO2 monitoring. In all ten infants, PaO2 was significantly lower and more variable during active as compared to quiet sleep. This fall in PaO2 during active sleep was accompanied by asynchronous (or paradoxical) chest wall movement. These findings may be important in our understanding of the higher incidence of apnea during active sleep in both preterm and term infants.