Infants and toddlers who slept fewer than 12 hours in a 24-hour period were twice as likely to be overweight than longer sleepers by the time they’re 3 years old, a study shows.
The children most likely to be overweight were those who slept less than 12 hours and watched at least two hours of television a day, says the study in the Archives of Pediatric and Adolescent Medicine.
Although previous research has linked inadequate sleep with weight gain in adults and older children and TV viewing and obesity in older children, the authors of the new study say theirs is the first to connect sleep and television viewing in infants to excess weight.
“One of the things we thought was that if children are sleeping less they might be watching more TV, and maybe that would explain the relationship between sleep and obesity,” says lead author Elsie Taveras, a Harvard pediatrician who runs the childhood obesity prevention clinic at Children’s Hospital Boston. “But that wasn’t the case.”
The children slept an average of 12.3 hours a day at age 6 months, 12.8 hours a day at 1 year and 12 hours a day at age 2. Some who slept more than 12 hours also watched more than two hours of TV a day, while some briefer sleepers didn’t.
Why less sleep in infancy and toddlerhood was linked to a greater chance of becoming overweight isn’t clear, says co-author Matthew Gillman, also a Harvard pediatrician. Gillman says some short-term experiments in adults suggest that “people whose sleep is curtailed do have hormone changes that tend to increase appetite.”