In 29 six-month-old infants, local sleep EEG features, namely frontal slow-wave activity asymmetry and prefrontal theta power, were associated with parent-rated temperament, indicating that sleep neurophysiology is a biological correlate of temperament during preverbal stages.
Greater left-hemispheric frontal slow-wave activity (SWA) during infant sleep was associated with higher orienting/regulatory capacity scores.
Higher theta power over an array of prefrontal electrodes during sleep was associated with lower negative affectivity scores.
Local sleep depth over frontal and temporal areas, indexed by SWA asymmetry and theta power, relates to self-regulatory abilities and affective traits in infants.
Sleep neurophysiology is proposed as a biological correlate of temperament in the preverbal stage, extending prior waking-state EEG findings.
This study asked whether the brain activity of babies while they sleep is linked to their temperament, meaning how strongly they react to things and how well they can regulate themselves. Researchers recorded overnight sleep in 29 six-month-old infants using a portable EEG cap with many sensors. Parents completed a questionnaire describing their baby's temperament, with a focus on negative affectivity (for example, tendency toward distress) and orienting/regulatory capacity (for example, attention and self-soothing). Babies with stronger slow-wave activity (a marker of deep sleep) in the left frontal brain region compared with the right had higher scores on orienting/regulatory capacity. Babies with more theta activity over the front of the brain during sleep had lower scores on negative affectivity. The authors suggest that how deeply different brain areas sleep, especially in frontal and temporal regions, may reflect early differences in self-regulation and emotional tendencies. This research suggests that sleep EEG could offer a way to study temperament in infants who cannot yet talk, without relying only on parent reports. The sample was small and the findings are correlations, so they do not show that sleep patterns cause temperament differences or that they can be used to predict individual children's outcomes.
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Upload Your LabsReicher V, Markovic A, Beaugrand M, Mühlematter C, Schoch S, Gácsi M, et al.. (2026). Sleep neurophysiology as a biological correlate of infant temperament.. Cerebral cortex (New York, N.Y. : 1991). https://doi.org/10.1093/cercor/bhag173