Background:
Inadequate sleep has been shown to be a contributor to obesity in both children and adults. Less evidence is available for toddlers and among those with higher obesity risk. The objective of this study was to examine the relationship between sleep patterns and body weight development in a group of young obesity-predisposed children, and to assess whether intakes of energy or macronutrients mediate this relationship.

Methods:
Participants included 368 Danish children aged 2–6 years from the Healthy Start Study, a 1.3 year randomised controlled intervention trial. Sleep habits were measured using a 7-day sleep diary. Multivariate linear regression with adjustment for confounders was used to assess the association of sleep duration and sleep variability with 1.3 year changes (Δ) in body mass index (BMI) z-score from baseline to follow-up.

Results:
The average nighttime sleep duration was 10.7 h (range 8.8–12.5 h). After controlling for potential confounders, a significant inverse association between nighttime sleep duration and ΔBMI z-score (β=−0.090, P=0.046) was observed. This relationship was mediated by energy intake, with all macronutrients contributing to this mediation effect. No associations were found for sleep variability and ΔBMI z-score but baseline intake of added sugars and sugary beverages were positively associated with sleep variability.

Conclusion:
Shorter sleep duration, mediated by energy intake in early in life, seems a risk factor for weight gain among young obesity-predisposed children.