September 7, 2010

Science Daily/American Academy of Sleep Medicine

A study in the Sept. 1 issue of the journal Sleep shows that teens who slept less than eight hours per weeknight ate higher proportions of fatty foods and snacks than adolescents who slept eight hours or more. The results suggest that short sleep duration may increase obesity risk by causing small changes in eating patterns that cumulatively alter energy balance, especially in girls.

Results show that a shorter mean weekday sleep duration was significantly associated with an increase in the percentage of calories consumed from fats and a decrease in the percentage of calories from carbohydrates. After adjusting for potential confounders such as age, sex and race, teens who slept less than eight hours on weeknights consumed 2.2 percent more calories from fats and 3.0 percent fewer calories from carbs than teens who slept eight hours or more. Further adjustments for body mass index (BMI) had little effect on these associations. In secondary analyses stratified by sex, the results were significant among girls but not boys.

"The relative increase in fat consumption among shorter sleepers by 2.2 percent per day chronically may contribute to cumulative increases in energy consumption that would be expected to increase risk for obesity and cardiovascular disease," said senior author and principal investigator Susan Redline, MD, MPH, professor of medicine in the Division of Sleep Medicine at Brigham and Women's Hospital and Beth Israel Deaconess Medical Center, teaching affiliates of Harvard Medical School in Boston, Mass.

"The demonstration of chronically altered dietary patterns in adolescents with shorter sleep provides insight into why shorter sleep has been associated with obesity in prior experimental and observational studies."

The study also found a relationship between sleep duration and snacking. For each one-hour increase in sleep duration, the odds of consuming a high amount of calories from snacks decreased by an average of 21 percent. Analyses of sleep duration and timing of nutrient intake revealed that a significantly greater proportion of teens who slept less than eight hours per weeknight consumed food in the early morning between 5 a.m. and 7 a.m.

"Altered timing of eating in shorter sleepers also may be a metabolic stress that contributes to metabolic dysfunction," said Redline.

http://www.sciencedaily.com/releases/2010/09/100901072854.htm