Early bedtimes may lower risk for obesity

Preschool-aged children who go to bed early are half as likely as those whose bedtime is late to be obese as adolescents, according to a new study. The investigation, conducted in 977 children enrolled in the Study of Early Child Care and Youth Development, defined early bedtimes as 8:00 pm or earlier and late bedtimes as after 9:00 pm.

Investigators analyzed data on the preschool-aged children’s typical weekday bedtime, as reported by their mothers, and measured their height and weight when they were aged about 15 years. One-quarter of the preschoolers had early bedtimes, one-half had bedtimes between 8:00 pm and 9:00 pm, and one-quarter had late bedtimes.

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The risk of obesity (body mass index for age, ≥95th percentile) increased with the lateness of bedtime: 10% of those with early bedtimes were obese, compared with 16% and 23% of those with the 2 later bedtimes, respectively. With adjustment for sociodemographic factors as well as “maternal sensitivity” (observed maternal behavior toward the child, ranging from supportive to hostile), the risk ratio for adolescent obesity was 0.48 for preschool-aged children with bedtimes at or before 8:00 pm, compared with such children with bedtimes after 9:00 pm, and 0.73 for bedtimes between 8:00 pm and 9:00 pm. The level of maternal sensitivity did not modify this risk (Anderson SE, et al. J Pediatr. 2016;176:17-22).

Commentary

It is not entirely clear that an early bedtime prevents obesity. It may be that this is an association without a cause-and-effect relationship, and if this practice does prevent obesity, we are not sure why. Although we lack all the answers, suggesting an early bedtime may be warranted and may be another example of advice that will benefit children throughout their lives. -Michael G Burke, MD 

Ms Freedman is a freelance medical editor and writer in New Jersey. Dr Burke, section editor for Journal Club, is chairman of the Department of Pediatrics at Saint Agnes Hospital, Baltimore, Maryland. The editors have nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article.