To examine the bidirectional relationship between short sleep duration and body mass index (BMI). A secondary aim was to investigate whether reduced physical activity and increased screen time (television and computer use) mediated these associations.
This study utilised data from the Longitudinal Study of Australian Children, which is an observational cohort study of Australian children. The sample included 2984 (52.4% boys) children followed from 4 to 5 years of age until 8 to 9 years of age. Sleep duration, screen time and covariates were reported by parents, with BMI measured objectively. Cross-lagged modelling investigated the bidirectional association between sleep duration and BMI; lagged panel mediation modelling examined physical activity and screen time as potential mediators.
Short sleep duration at 4 to 5 years of age was significantly associated with higher BMI at 8 to 9 years of age (β= −.07, p = .044). The relationship between short sleep duration at 4 to 5 years of age and higher BMI at 8 to 9 years of age was partially mediated by increased television viewing at 6 to 7 years of age (β = −.01, 95% confidence interval [−.02, −.002]).
Short sleep duration could be a risk factor for obesity in children. Increased television viewing may be one mechanism underlying this longitudinal relationship.