A Community-Based Study of Sleep and Cognitive Development in Infants and Toddlers

Study Objectives: To examine the prevalence and correlates of nighttime awakenings and to explore the association between sleep and cognitive development in a community sample of infants and toddlers. Methods: A total of 590 healthy infants (aged 2-11 months) and 512 toddlers (aged 12-30 months) from 8 provinces of China were assessed for their sleep and cognitive development. Data on sleep duration and nighttime awakenings were collected through the Brief Infant Sleep Questionnaire. Cognitive development was assessed by trained pediatricians using the Bayley Scales of Infant Development. Results: Prevalence of no nighttime awakening, and nighttime awakening(s) for 1x/night, 2x/night, and 3x/night was 6.8%, 20.2%, 33.2%, and 39.3% in infants, and was 25.8%, 34.6%, 23.8%, and 15.8% in toddlers, respectively. Nighttime awakenings were generally associated with younger age, lower maternal education level, and being currently breastfed. In addition, nighttime awakenings were associated with being boys in toddlers. After controlling for potential confounders, infants with nighttime awakenings for 2x/night were found to have significantly higher Mental Development Index (MDI) score, as compared to those without and those with more frequent nighttime awakenings. However, toddlers with nighttime awakenings for >= 3x/night had significantly lower MDI, as compared to those with fewer nighttime awakenings. Total sleep duration was not associated with any developmental indices in both infants and toddlers. Conclusions: Frequent nighttime awakenings are associated with poor cognitive functions in toddlers. Meanwhile, a nonlinear association between nighttime awakenings and cognitive performance was found among infants. The findings provide a developmental context for the effect of sleep on cognitive abilities in young children. Further longitudinal studies and interventional studies on the effects of parent-based sleep-focused intervention on cognitive abilities among young children are warranted.