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Late Bedtime = Weight Gain

Simply going to bed late on weeknights can set you up for gaining weight, no matter how much you exercise, how many hours of sleep you get or how much time you spend in front of a TV or computer screen. To arrive at this conclusion, researchers at the University of California, Berkeley analyzed data including bedtimes from 3,342 young people participating in a national study of adolescent health that has been ongoing since 1994. The investigators focused on three time periods – the onset of puberty, college-age years and young adulthood. Participants reported both their bedtimes and the number of hours they slept, and the researchers calculated BMIs based on each participant’s height and weight. Losing sleep due to late bedtimes was associated with a 2.1 gain in BMI over a five-year period. The findings suggest that going to bed earlier could set teens’ weight on a healthier track as they reach adulthood, said study leader Lauren Asarnow.

Why Late Night Eating is a Bad Idea

Eating late at night when you can’t sleep can lead to problems beyond weight gain - it may compromise your concentration and alertness. Researchers from the University of Pennsylvania report that adults consume about 500 extra calories late at night when their sleep is limited. To investigate the effects of those excess calories, the researchers gave 44 adults ages 21 to 50 unrestricted access to food and drink but allowed them to sleep for only four hours a night for three nights. On the fourth night, 20 of the participants could eat and drink all they wanted, while 24 were prevented from snacking - they were allowed to drink only water from 10 p.m. until their 4 a.m. bedtime. Each night at 2 a.m. during the study all the participants took tests to evaluate their working memory, cognitive skills, sleepiness, stress levels and mood. On the fourth night, participants who drank only water after 10 p.m. performed better on tests of reaction time and attention than those who had eaten, even though both groups had the same sleep restrictions.