This study aimed 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.  It included 107 children, of which 43 had normal-weight parents (low obesity risk), and 64 had  parents with overweight or obesity (high obesity risk). Sleep was measured yearly from ages 2 to 6 years by using actigraphy. The outcome variables, also measured annually, were BMI z score and waist circumference.  The researchers were able to objectively measure sleep characteristics via the wrist tracker rather than relying on information relayed by parents and children. 

The results showed that there was no difference in sleep patterns among children at different risks. A higher short sleep duration score was associated with a more significant increase in BMI z score across ages. Independently of sleep duration, higher late sleep score was associated with more substantial increases in BMI z score, and waist circumference. Moreover, compared with children at low risk and without habitual late sleep, children at high risk and with routine late sleep had more significant 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). So, from the results, it was concluded that more frequent exposures to late sleep were associated with more significant increases in adiposity measures from ages 2 to 6 years, particularly in children whose  parents had obesity. 

Journal of Pediatrics Feb 2020