CHICAGO — When the wind blows, the cradle will rock. And when babies sleep less, they may gain too much weight.
A new Harvard study finds babies and toddlers who sleep fewer than 12 hours daily are at greater risk for being overweight in preschool, startling evidence that the link between sleep and obesity may affect even young children.
TV viewing heightened the effect. The children who slept the least and watched the most television had the greatest chance of becoming obese.
“The two (behaviors) are acting independently. In combination, they are particularly risky,” said the study’s lead author, Dr. Elsie Taveras of Harvard Medical School.
The findings, published in April’s Archives of Pediatrics &Adolescent Medicine, are based on mothers’ reports of their babies’ sleep habits and TV viewing, and direct measures of the children’s height, weight and skinfold thickness.
Starting when the babies were 6 months old, mothers were asked how long their children napped during the day and how long they slept at night. Moms were asked again when the children were 1 and 2 years old. They were asked about TV time when the children reached age 2.
The researchers combined the sleep answers to find an average pattern for each child during the first two years of life. They found 586 of the children slept an average of 12 or more hours a day and 329 of the children slept less than that.
Among the long sleepers, 7 percent were obese at age 3.
The short sleepers fared worse. Twelve percent of them became obese 3-year-olds. Adding TV to the picture, 17 percent of those who slept less than 12 hours a day and watched two or more hours of television a day were obese by the time they were 3.
Obesity was defined as having a body mass index in the 95th percentile or above. BMI is a measure that combines height and weight. A 3-year-old who is 3 feet, 3 inches tall and 40 pounds would be considered obese.
The researchers took into account other risk factors for obesity, including TV viewing, and still found the children who slept fewer than 12 hours a day had a doubled risk of being obese at age 3 than the other children.
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