Children under five who do not get adequate sleep at night are at increased risk for later childhood obesity says a new study. The researchers found that daytime naps are not enough to compensate for sleep loss at nights in terms of preventing obesity. The study is published in the September issue of the journal Archives of Pediatrics & Adolescent Medicine.
The study included 1,930 U.S. children, ages 1 month to 13 years, who were divided into two groups, younger (ages 1 month to 59 months) and older (ages 5 to 13 years). The baseline data on the children was gathered in 1997 and again followed up in 2002. The data analyzed included information known to influence whether a child develops obesity, including parents' weight and the child's physical activity level, as well as how long the children slept at night and whether they napped during the day. On average, younger children in the study slept 10 hours a night, and older children slept around 9.5 hours, but some children in both age cohorts got as little as five hours' sleep a night.
Results showed that 33 percent of the younger children and 36 percent of the older children were overweight or obese. Among the younger children, lack of sufficient nighttime sleep at baseline was associated with increased risk for later overweight or obesity. Among the older children, the amount of sleep at baseline was not associated with weight at follow-up. But lack of nighttime sleep at follow-up was associated with increased risk of a shift from normal weight to overweight and obesity.
Janice F. Bell of the University of Washington in Seattle, and Frederick J. Zimmerman of the University of California, Los Angeles write that the results, “suggest that there is a critical window prior to age 5 years when nighttime sleep may be important for subsequent obesity status.” They added, “Sleep duration is a modifiable risk factor with potentially important implications for obesity prevention and treatment…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.” The actual reason behind this phenomenon is not precisely known, but the authors of the study said that getting less sleep could lead to “decreased physical activity due to tiredness and increased energy intake” because the waking child has more opportunities to eat.
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