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(NBC News) While early birds may gain that proverbial worm, they also may have an easier time managing their weight.
A new study suggests people exposed to at least 20 to 30 minutes of bright, morning light tend to have a lower Body Mass Index.
It appears light has an indirect effect on your waistline by having a direct effect on the brain.
"It affects hormones that regulate appetite, it affects hormones and neurotransmitters that regulate the sleep-wake cycle," explains Dr. Phyllis Zee of Northwestern Medicine.
Bright lights also help wake us and lift our mood, which might in turn prompt us to make healthier decisions throughout the day.
Dr. Phyllis Zee and colleagues at Northwestern Medicine studied 54 people for a week. Those who spent more time bathed in light sometime during the morning hours were leaner than those who got their light exposure during late afternoon or evening hours.
One of the keys may be the color of morning light, which is blue.
"It's a more powerful stimulus for your brain than let's say the red light or the orange light we get later in the afternoon," Dr. Zee notes.
The study could have important implications for shift workers whose internal clocks may benefit from bright, artificial lights.
And simply standing in the sunshine, sadly will not melt away pounds...but it could help if combined with a little morning exercise routine and a healthy diet.