Yet another reason to salute the sun: a new study shows that exposure to light in early morning hours is linked to lower body mass index (BMI).
Specifically, exposure to at least moderate light — about the amount of light present with bright indoor lighting — between the hours of 8 a.m. and noon was correlated to lower BMI.
Researchers at Northwestern University's Feinberg School of Medicine had 54 adults strap on an Actiwatch (which tracked sleep, wake and light-exposure data), and noted height and weight.
Participants with even moderate light exposure early in the day (between 8 a.m. and noon) had lower BMIs. Even more incredibly, the study found that every hour the first exposure was prolonged (for instance, moderate light exposure beginning at 9 a.m. instead of at 8 a.m.) was correlated with a 1.28 unit increase in BMI — which could mean an increase of more than five pounds in a 5'5" person, depending on initial weight.
While researchers did not find the same link between BMI and light exposure at other times of day, they found that the amount of light significant in terms of BMI was exposure to at least a level equivalent to what you might find in a bright home or office, according to the study — more than what would emanate from a single lamp and less than what is present on a cloudy day.
Researchers weren’t entirely sure how to explain the lack of BMI correlation at other times of day, but one theory is that morning light plays an important role in regulating metabolism and circadian rhythms, rousing us when we are supposed to naturally awake.
So, don't despair on rainy days! Just make sure you're getting the exposure before, after and during breakfast and all the way through the lunch hour.
Now, rise and shine!
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