While early birds may get that proverbial worm, they also seem to 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 all has to do with how light impacts the brain.

It affects hormones that regulate appetite, said Dr. Phyllis Zee, Northwestern Medicine. It affects hormones and neurotransmitters that regulate the sleep-wake cycle.

Morning light also help wake us and lift our mood, which might, in turn, prompt us to make healthier decisions throughout the day.

Dr. 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, said Dr. Zee.

The study could have important implications for shift workers, whose internal clocks may benefit from bright, artificial lights.

Simply standing in the sunshine, sadly, will not melt away those excess pounds, but it could help if combined with a little morning exercise routine and a healthy diet.

Light's effect on the brain does not require rays to enter the body through the skin, so experts remind folks to wear sunscreen.

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