Sleep is critical for the healthy development of children, including maintaining a healthy weight. Researchers have known that children who sleep less than 7.5 hours a night are at 3-fold increased risk for obesity. Now investigators are looking beyond the duration of sleep and digging into other sleep variables and their relationship to weight gain.

New findings suggest wake time and sleep midpoint may be relevant factors in the development of excess weight gain in younger patients, according to research reported in a poster presentation at the 39th Annual Meeting of The Obesity Society (TOS) at ObesityWeek® 2021. “Modifying sleep timing behaviors might be a viable strategy for the prevention of obesity among youth,” noted the study authors, who also published the findings in Obesity.

“Facets of sleep beyond total sleep duration [eg, sleep variability, sleep timing] have been linked to obesity risk in youth. However, there is a paucity of objectively measured longitudinal sleep data,” the authors stated.

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Using a longitudinal design, the investigators tested several facets of sleep to determine if they were associated with obesity risk in younger patients. The study included 137 children aged 8 to 17 years (mean age, 12.5) who had good general health across the weight spectrum. The study was fairly evenly split between girls (54%) and boys (46%); 28.4% of participants identified as non-Hispanic Black or Black.

Participants were asked to wear wrist actigraphy monitors (ActiGraph GT3X+ activity monitor) for approximately 14 days following the baseline visit. The monitor delivers 24-hour physical activity and sleep/wake measurements such as average weekly sleep duration, within-person sleep duration variability, weekend catch-up sleep, bedtime and wake time shift, social jet lag, bedtime, wake time, and sleep midpoint.

Fasting body weight and height were used to calculate the BMI of each participant. Kilograms of lean mass and total fat mass were measured via dual-energy x-ray absorptiometry and the percentage of both was calculated by the values obtained. Depressive symptoms were also assessed beforehand using the Children’s Depression Inventory 2.

At baseline, fat mass was reported at 15.3 kg and 1-year fat mass equaled 17.0 kg; 28.5% of participants presented with overweight or obesity.

The average weekly sleep duration of all nights and weekend catchup sleep was calculated by subtracting average hours per night of weekend sleep from average hours per night of weekday.

The authors reported that earlier wake-up time and earlier midpoint were associated with higher 1-year fat mass, after adjusting for baseline fat mass and height. Average weekly sleep duration, sleep variability, and bedtime were not associated with weight gain.

The authors concluded that wake timing may be associated with greater gains in fat mass over time but that “more data among larger samples of youth across a wide age and weight spectrum, collected throughout the entire year, are needed to provide clarification on how circadian preference impacts the association between sleep timing and onset of obesity.”


Lemay-Russell S, Schvey N, Kelley N, et al. Longitudinal associations between facets of sleep and adiposity in youth. Presented at: ObesityWeek® 2021; Nov. 1-5, 2021.