HEART-RATE CHANGES DURING SLEEP IN NORMAL 2-MONTH-OLD INFANTS

Thirty-five normal two-month-old infants had nighttime followed by day time polygraphic recordings. Heart rates were calculated every minute in active and quiet sleep states. A difference in mean heart rates was found between the two slates and between the two recordings. Rates we re lower at night than during the day (P < 0.0001), regardless of the sleep state, During nighttime or daytime recordings as a function of s leep cycles or during sustained sleep episodes, heart rates were minim al in the middle of recordings, but differences were statistically sig nificant for only a few results (mainly in QS). Intrasleep awakening l ed to a marked increase in heart rate after sleep was resumed, althoug h differences were only statistically significant when the awakened in fant was fed. Infants with episodes of periodic breathing had lower me an heart rates throughout the recordings. but differences were not sta tistically significant, Respiratory and heart rates showed similar cha nges during the recordings, and a statistically significant correlatio n was found between the two measurements.