Earlier bedtimes can decrease obesity in adolescents, study says

Earlier bedtimes can decrease the rate of obesity during adolescence and during the transition to adulthood, says a study by researchers published in the journal Sleep. Researchers concluded, "Later average bedtime during the workweek, in hours, from adolescence to adulthood was associated with an increase in body mass index (BMI) over time." The 12th Annual State of Obesity report, released last month, found that the largely rural South is the most obese region in the country.

For the study "researchers followed 3,342 adolescents from 1996 to 2009 and interviewed them three times during the study period about their bedtimes, food consumption, exercise and television watching," Ariana Eunjung Cha reports for The Washington Post. "They also measured the volunteers' heights and took their weights to calculate their BMI during each of the check-ins. They found that the later the average bedtime during the schoolweek, the higher the BMI over time. More precisely, they found that for every minute of later bedtime there was an increase in BMI of 0.035 kg/m2. Or for every additional hour later a 2.1 increase in BMI."

Lauren Asarnow, a doctoral candidate at the University of California at Berkeley and co-author of the study, said in a statement, "The results are important because they highlight adolescent bedtimes, not just total sleep time, as a potential target for weight management concurrently and in the transition to adulthood." (Read more)