Background: Few studies on the relationship between sleep quantity and/or quality and cognition have been conducted among preschoolers from the healthy general population. We aimed to identify, among 3-year-old children, early polysomnography (PSG) sleep factors associated with estimated intelligence quotient (IQ) using the Weschler Preschool and Primary Scale Intelligence-III test (WPPSI-III) and its indicators: full-scale (FISQ), verbal (VIQ), and performance (PIQ) intelligence quotients.
Methods: We included full-term children from the French birth-cohort AuBE with PSG recording at term (M0) and/or six months (M6), and available WPPSI-III scores at three years. Sleep and arousal characteristics of these infants were evaluated during day and night sleep periods. Relationships between IQ scores and sleep parameters were estimated using models with the child as a repeated effect adjusted for time (night/day), maturation (M0/M6), tobacco exposure (yes/no), anxiety-depressive scores during pregnancy, maternal age, duration of breastfeeding and child's gender.
Results: A total of 118 PSG recordings were obtained, representing a total of 78 unique children (38 with one PSG and 40 with two PSG). No correlations were found between night and day sleep durations at M0 or M6. Mean VIQ, PIQ, and FSIQ scores were within normal ranges. In multivariate models, longer sleep duration and higher sleep efficiency during the day were negatively associated with all IQ scores. More frequent arousals during the night were associated with lower VIQ scores.
Conclusion: Early sleep characteristics such as night sleep fragmentation or longer naps could be associated with impaired cognitive function at three years of age.
Keywords: Arousal; Cohort study; Infant; Intelligence quotient; Preschoolers; Sleep.
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