Diet and exercise are the linchpins of healthy weight, but a new study in teenagers suggests another key player: sleep.
Teenagers who got less than eight hours of sleep at night ate more fatty foods and snacks than their better-rested peers, potentially setting themselves up for obesity, the study found. The connection between hours of sleep and snacking was strongest in girls.
“Otherwise healthy adolescents who had mild sleep deprivation consumed more calories and mostly from fat,” Dr. Susan Redline, now a sleep medicine specialist at Brigham and Women’s Hospital, said in an interview. She worked on the study, whose results are published in the journal Sleep, when she was at Case Western Reserve University School of Medicine in Cleveland.
Previous research conducted in sleep labs has connected sleep deprivation to weight gain, but her team studied 240 teenagers who were living at home. The participants, who were 16 to 19 years old and part of an ongoing sleep study, wore devices on their wrists that calculated how many hours they slept on three weeknights. Research staffers quizzed them on the foods they ate.
Only about a third of the teens slept the recommended nine hours a night or more; the average amount of sleep was about seven and a half hours per night. Eighteen percent met the definition of obesity.
The teens who slept less than eight hours consumed 2.2 percent more calories from fat and 3 percent fewer calories from carbohydrates than teens who slept eight hours or more. The increase in fat may not seem like much, Redline said, but small increments in food intake can lead to weight gain over time.
Girls who slept less than eight hours got 3.3 percent more calories from fat than teens who slept longer, compared to the 0.9 percent more fat consumed by boys, but the reason for the difference is not clear. The girls may have reported what they ate more accurately, for example, or they may have been more likely than the boys to eat fatty snacks in response to higher stress, the authors speculated.
The study can’t say that sleeping less caused the teens to eat high-fat snacks, but it suggests an association between shorter sleep and higher fat consumption whose mechanisms should be studied further, the authors said. Combined with other research, that means sleep shouldn’t be ignored in obesity prevention programs that concentrate on diet and exercise, Redline said.
“Healthy sleep habits are important for health in general," she said. "In addition to attention to diet and exercise and activity, healthy sleep ... is something that should be taught.”
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