Early childhood sleep patterns and cognitive development at age 6 years: The generation R study

Abstract

Objective To explore the association of sleep duration and awakening frequency with cognitive outcomes in young children. Methods Mothers of 2,800 children from the Generation R cohort reported sleep duration and awakenings at children's age 24 months. At age 6 years, validated Dutch measures were used to assess children's nonverbal intelligence and language comprehension. Results We found a nonlinear association of total sleep time at 24 months with nonverbal intelligence (p=0.03) and language comprehension (p=0.04) at 6 years. Toddlers sleeping within the recommended 11-14 hr had more favorable cognitive development compared with both extremes. Frequent awakenings were negatively associated with nonverbal intelligence, but not with verbal comprehension. Conclusion Sleep duration in toddlerhood has an inverted- U-shaped relation with childhood cognitive measures. Frequent awakenings are associated with lower nonverbal intelligence. Given the marked decline in sleep duration and awakenings in toddlerhood, developmental changes of sleep patterns might be important for cognitive development.