Insufficient amounts of nighttime sleep among infants and preschool-aged children may be a significant risk factor for developing childhood obesity, according to a report in the September issue of Archives of Pediatrics & Adolescent Medicine, one of the JAMA/Archives journals. Additionally, napping does not appear to be an adequate substitute for nighttime sleep in terms of preventing obesity. 

Using existing national, longitudinal, and panel survey data collected for children and adolescents, Janice F. Bell, PhD, MPH, University of Washington, Seattle, and Frederick J. Zimmerman, PhD, University of California, Los Angeles, studied 1,930 children ages 0 to 13 years, with data collected on the same children in 1997 (baseline) and again in 2002 (follow-up). For the purposes of the study, children were separated into a "younger" group (age 0 to 59 months) and an "older" group (age 60 to 154 months).

The authors found that "at follow-up, 33 percent of the younger cohort and 36 percent of the older cohort were overweight or obese." For the younger children, short duration of nighttime sleep at baseline was associated with an increased risk of subsequent overweight or obesity. In the older age group, baseline sleep was not associated with subsequent weight status; however, contemporaneous sleep was associated with increased odds of a shift from normal weight to overweight or from overweight to obesity at follow-up. Additionally, in the older group, nighttime sleep at follow-up was associated with marginally increased odds of obesity at follow-up while sleep duration 5 years prior had no meaningful effect. According to the authors, "These findings suggest that there is a critical window prior to age 5 years when nighttime sleep may be important for subsequent obesity status."

"Sleep duration is a modifiable risk factor with potentially important implications for obesity prevention and treatment," the authors conclude. "Insufficient nighttime sleep among infants and preschool-aged children appears to be a lasting risk factor for subsequent obesity, while contemporaneous sleep appears to be important to weight status in adolescents. Napping had no effects on the development of obesity and is not a substitute for sufficient nighttime sleep.”