Sleep-wake cycle of the healthy term newborn infant in the immediate postnatal period

Objective: To examine sleep-wake cycle (SWC) composition of healthy term infants in the immediate postnatal period using EEG, and investigate factors that might influence it. Methods: Multichannel video-EEG was recorded for a median of 61.9 min (IQR: 60.0-69.3). The absolute and relative scores of sleep states were calculated for each infant's recording. Parametric/non-parametric statistical tests and multiple linear regression analysis were used to investigate the influence of perinatal factors on SWC composition. Results: Eighty healthy term infants aged 1-36 h were studied. A well-developed SWC was evident as early as within the first 6 h after birth. The mean (SD) percentage of active sleep (AS) was 52.1% (12.9) and quiet sleep (QS) was 38.6% (12.5). AS was longer and QS shorter in infants delivered by elective caesarean section (CS) compared to infants delivered by vaginal delivery or emergency CS. Conclusions: This is the first large cohort EEG study that has quantified neonatal sleep. SWC is clearly present immediately after birth, it is dominated by AS, and is influenced by mode of delivery. Significance: This knowledge of the early neonatal EEG/SWC can be used as reference data for EEG studies of neurologically compromised infants.