Sleep duration of less than 12 hours per day during infancy may predict childhood overweight, researchers reported.
In a prospective study of 915 mother-child pairs, sleep curtailment at age 6 months to 2 years doubled the odds that, at age 3 years, a child would show increased adiposity, as measured by both body mass index and skinfold thickness, according to Dr. Elsie M. Taveras and her associates at Harvard Medical School, Boston.
They described this study as the first to report a link between infant sleep duration and childhood overweight. The findings are consistent with data from previous studies involving older children and adolescents, they noted.
They analyzed data from a cohort study of gestational factors and offspring health in Massachusetts residents. The children's sleep duration was assessed at ages 6 months, 1 year, and 2 years. Adiposity was assessed at age 3 years, at which time 9% of the children were overweight (defined as a BMI for age and sex at the 95th percentile or greater).
In the first analysis of the data, “[we] observed an approximately twofold higher prevalence of overweight in children who slept less than 12 hours in a 24-hour period.” But short sleep duration was also associated with having a single parent, lower household income, lower maternal education status, nonwhite ethnicity, and longer durations of television viewing.
Further analysis adjusted for these potentially confounding factors, as well as for maternal BMI and smoking status, and for infant birth weight and activity level, but the association changed only minimally after the adjustments.
The combination of short sleep duration and extended durations (2 hours or more per day) of television viewing appeared to be synergistic and “was associated with markedly higher” adiposity, the investigators said (Arch. Ped. Adolesc. Med. 2008;162:305–11).
The mechanism by which infant sleep curtailment affects later adiposity is not yet clear. In adults, sleep restriction can reduce leptin levels and elevate ghrelin levels, both of which are likely to increase appetite.
Increased time awake also allows more time for eating. And it may increase daytime sleepiness, which in turn may reduce physical activity and promote overweight, the authors wrote.
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