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Lose Weight By Sleeping: Early Bedtimes Mean Lower BMI

What if losing weight was as simple as going to sleep earlier?

Researchers at UC Berkeley have concluded in a study of 3,300 people that a direct link exists between bedtime and Body Mass Index (BMI). Those who typically head to bed early were found to have a lower BMI than those who stay up late.

The correlation identified by researchers suggests that for every hour later a person stayed up, an average of 2.1 points on the BMI chart was gained in its place. This increase was identified even among those who slept for identical lengths of time, and the effects of a later bedtime on BMI was not mitigated by exercise. Those who slept late in an attempt to compensate for going to bed late were still impacted by a higher BMI.

BMI factors in a person’s weight and height to calculate the amount of body fat the person has.  On the Body Mass Index chart, 18.5 to 24.9 is healthy, 25 to 29.9 is overweight, and anything greater is considered obese.

According to the National Institutes of Health, obesity is a major problem among Americans. Data from a survey collected in 2009 and 2010 showed that 35.7 percent of adult Americans are obese. 74 percent of men were found to be overweight, while women did slightly better at 64 percent.

Only 31.2 percent of Americans in the NIH survey were found to have a normal BMI.

Lauren Asarnow, the author of the study and a doctoral candidate at UC Berkeley, spoke to CBS News about the connection between obesity and sleep, or a lack thereof. “Obesity is obviously growing among adolescents and adults,” she said. “There’s also an epidemic of lack of sleep and later bed time preference in teens.”

Asarnow pointed out that the idea of a correlation between BMI and bedtime is not new, but no one has bothered to analyze the effects of sleep on body weight over the long term.

There’s been some literature looking at the relationship late bedtimes and weight gain cross-sectionally, but no one’s ever looked at what happens long term.

Asarnow has a theory to why the association exists, suggesting that those who stay up late may happen to also have poor eating habits, snacking in the wee hours of the morning. People that sleep late are also more likely to skip breakfast, a habit researchers have previously found to be linked to weight gain.

Fortunately, erratic sleep patterns can easily be corrected. Asarnow recommends that people, especially teenagers, make an effort to go to sleep earlier so that they can experience the weight loss benefits associated with healthy sleep habits.

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