Infant sleep during the first postnatal day: an opportunity for assessment of vulnerability.

OBJECTIVE

The purpose of this study was to describe the sleep of newborns throughout the first 48 postnatal hours and to relate their earliest sleep characteristics to developmental status at 6 months.

METHODS

The sleep of 36 healthy newborns was recorded continuously throughout the first two postnatal days, starting immediately after birth, using an automated Motility Monitoring System. The Motility Monitoring System consists of a pressure-sensitive mattress pad connected to an amplifier and a small 24-hour analog recorder. A single channel of analog signals produced by the newborn's respiration and motility is continuously recorded onto a 60-minute cassette tape. The signals are digitized and scored, in 30-second epochs, for Active Sleep, Quiet Sleep, Active-Quiet Transition, Sleep-Wake Transition, and Wake. In addition to the percent of time spent in each state, the Mean Bout Length of Active Sleep, Mean Bout Length of Quiet Sleep, Mean Sleep Period, Longest Sleep Period, and Arousals in Quiet Sleep were also measured.

RESULTS

On postnatal day 1, four measures were significantly related to 6-month Bayley mental scores: Mean Sleep Period, Longest Sleep Period, Sleep-Wake Transition, and Arousals in Quiet Sleep; and two measures were significantly related to Bayley motor scores: Mean Sleep Period and Sleep-Wake Transition. On postnatal day 2, none of the measures were related to mental scores, while two measures were related to the motor scores: Quiet Sleep and Mean Bout Length of Quiet Sleep.

CONCLUSIONS

The results suggest that the newborn's sleep characteristics during the first postnatal day provide uniquely sensitive indices of later neurobehavioral function.