ULTRADIAN AND DIURNAL CYCLICITY IN THE SLEEP STATES OF NEWBORN-INFANTS DURING THE FIRST 2 POSTNATAL DAYS

Objective: The purpose of this study was to investigate both ultradian and diurnal cyclicity in the deep states of newborn fullterm infants during the first 2 postnatal days. Methods: The sleep of 31 healthy ne wborn infants was recorded continuously throughout the first 2 postnat al days, starting immediately after birth, using an automated Motility Monitoring System (MMS). The MMS consists of a pressure sensitive mat tress pad connected to an amplifier and a small 24-h analog recorder. A single channel of analog signals produced by the infant's respiratio n and body movements was recorded and then scored in 30-s epochs for A ctive Sleep, Quiet Sleep, Active-Quiet Transition, Sleep-Wake Transiti on, and Wake, Data Analyses: The 48 h of recording were divided into s uccessive 12-h periods from 07:00 h to 19:00 h (day) and 19:00 h to 07 :00 h (night), and all measures were derived for each day and night pe riod. Both cross-sectional and repeated measures analyses were used be cause all babies were not represented in all day/night periods. Result s: Day/night differences in state variables: On both days, there was g reater Wakefulness, shorter Quiet Sleep Bout Lengths, shorter Mean Sle ep Periods and shorter Longest Sleep Periods during the daytime. On da y 1 only; there was less Quiet Sleep, shorter Quiet Sleep Bout Lengths and more Sleep-Wake Transition during the daytime. On day 2, repeated measures analyses revealed two additional day/night differences: less Quiet Sleep and more Sleep-Wake Transition during the daytime. Day/ni ght differences in Quiet Sleep cyclicity: 28 deep periods met the crit eria for analysis of Quiet Sleep cyclicity, and only six of these occu rred during the daytime. Seventeen of 28 analyzable sleep periods show ed significant Quiet Sleep cyclicity. Only two of these occurred durin g the daytime. Conclusions: Contrary to the prevailing view of develop ing sleep rhythms, the results of this study suggest that newborn infa nts exhibit both ultradian ad diurnal cyclicity in their sleep pattern s from the earliest postnatal period.