Progressive shortening of the periodic breathing cycle duration in normal infants.

Ten normal full-term neonates were monitored by oxycardiorespirography in hospital during the 1st wk of life, and subsequently at home at 4, 8, and 12 wk of age in a longitudinal study of the duration of the periodic breathing cycle during spontaneous sleep. Periodic breathing was observed in 25 of the 40 studies, with a total of 168 epochs of periodicity noted. Eighty-four percent of the periodic epochs occurring during nonrapid eye movements were preceded by a sigh, body movements, or sleep state transition, compared with 41% during rapid eye movements (p less than 0.005). There was a progressive reduction in the periodic breathing cycle duration, which fell significantly between the 1st and 4th wk, in both sleep states, (p less than 0.001). There was a further significant fall between 4 and 12 wk in nonrapid eye movement sleep (p less than 0.05), and there was no significant difference between sleep states at any postnatal age. The overall change in the duration of the periodic cycle, for both sleep states combined, was from 15.0 +/- 3.6 s at less than 1 wk to 12.4 +/- 1.8 s at 12 wk of age. The periodic breathing cycle duration progressively shortens over the first 3 months of life. We postulate that this shortening may be useful indicator of peripheral chemoreceptor maturation over this time period.