The contribution of good sleep to working memory in preschool: A matter of sleep quality or duration?

Good sleep is essential for efficient cognitive performance. The present research examined the link between sleep and working memory (WM) during early childhood, a period of major advances in neurodevelopment. The sample included 80 healthy children, 40 3-year-olds and 40 4-year-olds, attending childcare settings. The children were individually tested using WM tasks; parents completed sleep questionnaires. On a group level, WM improved with age. Process model analysis demonstrated the effect of age on WM (P=0.001) and indicated an age-specific involvement of sleep quality (P=0.01). Whereas sleep duration was not associated with WM, at 4years of age, sleep disturbance with physical symptoms (e.g., breathing, motor) was associated with poor WM performance. Among 3-year-old girls, fear-related sleep disruption was associated with better WM performance. Together, the results suggest that the association between sleep and WM is dependent on: (a) specific aspects of sleep, (b) age, and (c) gender. More research is essential for unraveling the underlying neuro-maturational processes and mechanisms.