Background The normal EEG in the early postnatal period has been incompletely defined in the past.
Aim To characterise and quantify the normal EEG during sleep in the early newborn period.
Methods Continuous multichannel video-EEG was recorded for up to 2 h in normal term babies within 12 h of birth. The total amount of active sleep (AS) and quiet sleep (QS) was calculated in the first hour of recording. Ten minutes of artefact-free periods of AS and QS were selected in each record. Spectral edge frequency, spectral entropy and relative delta power were calculated for each segment of AS and QS. Statistical analysis was performed using Wilcoxon signed rank tests.
Results 30 babies were studied: 10 within 6 h and 20 within 12 h of birth. Continuous, symmetrical and synchronous EEG activity and well-developed sleep–wake cycling was present in each case with the percentage of AS 52.9% (±13.9) and 51.0% (±12.8) and QS 35.0% (±13.3) and 38.8% (±9.6) in the early and later groups, respectively. Significant differences in each of the quantitative measures were evident between AS and QS at 0–6 h (p<0.05) and 7–12 h (p<0.0001).
Conclusion The normal newborn EEG contains continuous symmetrical and synchronous activity with well-developed sleep–wake cycles, even within 6 h of birth. Quantitative analysis of the EEG in the early postnatal period reveals very different results for AS and QS. These findings may have implications for quantitative analysis of the newborn EEG in babies with hypoxic–ischaemic encephalopathy.