New research suggests that you may be able to sleep yourself skinny—at least during infancy.

Infants who get fewer than 12 hours of sleep a night are more likely to be overweight, according to a recent study by researchers at Harvard Medical School.

Twenty-six percent of children between the ages of two and five are overweight or at risk to be overweight, a condition that can cause obesity, asthma or, type 2 diabetes later in life.

The study, published in the Archives of Pediatrics and Adolescent Medicine, is the first to examine sleep patterns in infants, though much work has been done on the effect of sleep on adults.

Studies on adult populations have shown that a lack of sleep is correlated with increased levels of a stomach hormone called ghrelin which can stimulate hunger.

Elsie M. Taveras, the study’s lead investigator and a professor at the Medical School, said that the physiological mechanism that causes childhood obesity is not yet well understood.

The researchers analyzed data on 915 infants collected through Project Viva, a study examining pregnancy and early development that was led by Medical School professor Matthew Gillman, one of the study authors.

Mothers were interviewed about the average time that their children slept at six months, one year and two years old.

Children were also measured for body mass index, a ratio of weight to height that is used as an indicator of health risks.

While the average child in the study slept 12.3 hours per day, the study found that black and Hispanic children were more likely than white children to receive less than 12 hours of sleep each night.

Television viewing was also shown to be a risk factor in overweight children.

The effects of sleep deprivation were found to be particularly apparent in children who watched more than two hours of television per day.

Taveras said that parents should take measures to ensure a relaxing sleep environment for their children, and that “dimming the lights around bedtime, a calming bedtime routine, [and] not a lot of TV or media exposure” can help children develop a consistent sleep schedule.

Some parents said that the study surprised them.

“It’s counterintuitive,” said Linda Chang, a mother of four whose husband attends the Harvard Kennedy School. “You think when you’re awake and active you burn more calories than when you sleep.”

—Staff writer Laura C. McKiernan can be reached at lmckiern@fas.harvard.edu.

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