RECTAL TEMPERATURE-CHANGES DURING SLEEP STATE TRANSITIONS IN TERM ANDPRETERM NEONATES AT POSTCONCEPTIONAL TERM AGES

Mean rectal temperatures in neonates were investigated during sleep st ate transitions as assessed by visually analyzed electroencephalograph ic-polygraphic recordings. Continuous 3-hour studies were obtained on 3 term and 5 preterm infants at postconceptional term ages using a 24- channel computerized monitoring system, In the study, 1,461 min were a ssigned an EEG state by traditional criteria. Mean rectal temperature measurements were tabulated for each minute of sleep. Data were analyz ed both as 1,461 consecutive minutes of sleep, and as 28 complete ultr adian neonatal sleep cycles. Exploratory analyses were performed using t tests, Mann-Whitney U tests, and one-way analysis of variance. Decr eases in mean rectal temperatures followed a transition from active to quiet sleep for only the term group. The preterm group had higher tem peratures at sleep onset than the term group and demonstrated no chang es during state transitions. Higher temperatures were maintained in th e preterm group during both active and quiet sleep (i.e., 36.7 degrees C versus 36.4 degrees C, P =.02) when 28 complete cycles of sleep wer e compared and during the transition when 658 min of active sleep were compared to 617 min of quiet sleep. These findings are preliminary; h owever, the phenomenon of state-dependent changes in mean rectal tempe rature in neonates based on electroencephalographic sleep is unreporte d. Higher mean rectal temperatures during active sleep and altered tem perature responses during transition to quiet sleep in the preterm inf ant suggest altered brain function because of the preterm infant's ada ptation to the extrauterine experience.