Study: Early Sunlight Exposure Can Keep Weight Down

By Joe Gullo

Published 04/04 2014 10:37AM

Updated 04/04 2014 10:39AM

There may be a new good reason to rise and shine this morning. A new study suggests that making the most of the sun coming up could help keep your weight down.

If there was ever a reason to stop pressing the snooze alarm, this could be it. Northwestern University School of Medicine researchers behind this study say its the first ever to report that the time of day that you're in the light could impact how much you weigh. Here's how it works:

Researchers  found that people who got most of their exposure to light early in the day had a significantly lower body mass index than those who got most of their light later in the day. In fact, they found light impacted about 20% of someone's BMI.

BMI is a measure of body fat, based on a person's height and weight.

So why does this happen? You might think it's because people who get up earlier are working out, but researchers said that wasn't the case. They said light exposure influence was independent of activity level, calories, sleep pattern, age or season.

Researchers said the key time to get bright light is between 8 a.m. and noon. If you get just 20 to 30 minutes during that time, it can impact BMI.

But there's a potential catch. Scientists say indoor light is usually not strong enough to reach the light level of influencing your BMI.

Time of day mattered, too because researchers said early morning light waves have more of the blue light that is most likely to impact your circadian rhythms, that's your sleeping and waking cycle. Experts say those rhythms plays an important role in regulating metabolism so, while that afternoon sun feels good, it may have less of an impact.

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