OBJECTIVES: To compare sleep in young children at different obesity risks, which were based on parental weight, as well as to explore the longitudinal associations of sleep characteristics with adiposity.

METHODS: In total, 107 children from an obesity prevention project were included, of which 43 had normal-weight parents (low obesity risk) and 64 had overweight and/or obese parents (high obesity risk). Sleep was measured yearly from ages 2 to 6 years by using actigraphy. Five sleep characteristics, that of late sleep, long sleep latency, short sleep duration, low sleep efficiency, and irregular sleep onset, were defined and scored across ages, with a higher score indicating more frequent exposure. The outcome variables, also measured yearly, were BMI z score and waist circumference.

RESULTS: There was no difference in sleep patterns among children at different risks. Higher short sleep duration score was associated with a greater increase in BMI z score (0.12; 95% confidence interval [CI] 0.01 to 0.25) across ages. Independently of sleep duration, higher late sleep score was associated with greater increases in BMI z score (0.16; 95% CI 0.05 to 0.27) and waist circumference (0.60 cm; 95% CI 0.23 to 0.98). Moreover, compared with children at low risk and without habitual late sleep, children at high risk and with habitual late sleep had greater increases in BMI z score (0.93; 95% CI 0.40 to 1.45) and waist circumference (3.45 cm; 95% CI 1.78 to 5.12).

CONCLUSIONS: More frequent exposures to late sleep were associated with greater increases in adiposity measures from ages 2 to 6 years, particularly in children with obese parents.