April 3, 2014

Brett Smith for redOrbit.com Your Universe Online

By most accounts, a healthy lifestyle should include a balanced diet, regular exercise, and according to a new study published in the journal PLOS ONE a long dose of bright light in the morning.

In the study, researchers from Northwestern University found that the time, strength and duration of light exposure is directly linked to body mass index (BMI), even after considering confounding factors.

The earlier this light exposure occurred during the day, the lower individuals body mass index, said study author Kathryn Reid, professor of neurology at Northwestern University. The later the hour of moderately bright light exposure, the higher a persons BMI.

Light exposure accounted for approximately 20 percent of a persons BMI. The impact of morning light exposure was found to be separate from a persons physical activity level, caloric consumption, sleep habits, age or time of year.

Light is the most potent agent to synchronize your internal body clock that regulates circadian rhythms, which in turn also regulate energy balance, said senior author Dr. Phyllis C. Zee, a professor of neurology at Northwestern University. The message is that you should get more bright light between 8 a.m. and noon.

If a person doesnt get sufficient light at the appropriate time of day, it could de-synchronize your internal body clock, which is known to alter metabolism and can lead to weight gain, she added.

According to the study team, the predominantly indoor lifestyle of the typical American means they do not get enough normal light in the morning to have a decreasing influence on BMI, which they said was between 20 and 30 minutes of exposure. Americans also work in poorly lit environments, usually about 200 to 300 lux much less than the magic number of 500 lux discovered to lower BMI in the study. On a cloudy day, outdoor light is greater than 1,000 lux. The study team said it is difficult to achieve even this level of light intensity with typical indoor lighting.

Light is a modifiable factor with the potential to be used in weight management programs, Reid said. Just like people are trying to get more sleep to help them lose weight, perhaps manipulating light is another way to lose weight.

Excerpt from:

A Good Dose Of Morning Sunlight Keeps Off The Pounds: Study