Respiratory and motor events in sleeping infants: their correlation with thoracico-abdominal respiratory relationships.

28 polygraphic recordings were made in normal infants: 20 in full-term newborns and 8 in 2- to 10-wk-old babies. In full-term newborns sighs and apneas (greater than 5 sec) were significantly more numerous in active (REM) sleep, while startles prevailed in quiet (NREM) sleep. The incidence of all these events diminished with age. Important interindividual differences of their frequency were noted in normal babies. There were not time correlations between the apneas (decreasing from newborns to 2-10 wk of age) and out-of-phase respiration in active sleep (no changing during the same period). Sighs, apneas, startles and limb movements did not modify phase relationships between thoracic and abdominal movements. Where movements were out of phase, only body movements involving the thorax were followed by transient period with in phase respiratory movements. Coincidences between occurrence of sighs, apneas, startles, gross body movements and respiratory amplitude diminution were calculated. There was no constant parallelism between out-of-phase thoracico-abdominal respiration and tonic chin activity inhibition nor respiratory rate irregularity. A hypothesis on neurological mechanism underlining these phenomena is proposed.