Sleeping less in infancy linked to being overweight in preschool

Infants who sleep less than 12 hours per day have an increased risk of being overweight as preschoolers than those who sleep 12 hours or more, according to a report in the April issue of Archives of Pediatrics & Adolescent Medicine, a theme issue on children and sleep.

About one-fourth of children age 2 through 5 years are overweight or at risk for being overweight, according to background information in the article. Previous studies in adults, adolescents and older children have shown that restricting sleep changes hormone levels, which could stimulate hunger and increase weight gain.

Elsie M. Taveras, M.D., M.P.H., of Harvard Medical School and Harvard Pilgrim Health Care, Boston, and colleagues studied 915 children whose mothers visited a group practice in eastern Massachusetts for prenatal health care. Children were weighed and measured in person immediately after birth and again six months and three years later. Mothers reported their children's sleep habits at these visits and on questionnaires one and two years after birth. Based on these reports, the researchers calculated each child's average daily sleep duration between age 6 months and 2 years.

Overall, the infants slept an average of 12.3 hours per day. As 3-year-olds, 83 children (9 percent) in the study were overweight. After adjusting for other factors that influence weight—including their mothers' body mass index (BMI) before pregnancy—infants who slept less than 12 hours per day had a higher BMI for age and sex, higher skinfold thickness (another measure of overweight) and were more likely to be overweight at age 3 than children who slept 12 hours or more per day as infants.

Adjusting for the amount of television viewed only minimally changed the associations between sleep and overweight, the authors note. However, the combination of little sleep and more hours spent watching television conferred the highest risk of being overweight. “Our findings lend support to childhood overweight prevention interventions that target both reduction in television viewing and ensuring adequate sleep duration,” the authors write.

“The mechanisms underlying the association between sleep duration and adiposity [amount of body fat] are unclear,” the authors write. In addition to altering hormone levels, sleeping less at night may lead to daytime sleepiness and reduced activity levels during waking hours, they note. Finally, more time spent awake could offer more opportunities to eat.

“Strategies to improve sleep duration among young children may be an important component of behavioral interventions that promote childhood overweight prevention,” the authors conclude. “Our findings suggest that clinicians and parents may wish to use evidence-based sleep hygiene techniques to improve sleep quality and perhaps increase sleep duration.”