A new study suggests that people exposed to at least half-hour of bright, morning light tend to have a lower body mass index (BMI). This is all about chemistry.
The researchers at Northwestern University’s Feinberg School of Medicine discovered a new way to measure the combined impact of light timing, duration, and intensity on BMI. The BMI is a ratio of height to weight, which determines if a person is underweight, normal, overweight, or obese. The study is published in the latest issue of PLOS ONE.
“For every hour later in which an individual got the majority of their light exposure, that translated into 1.22 BMI units,” — or 5 pounds to 10 pounds on a 5-foot-8 person, says Dr. Phyllis Zee to NBC News. Dr. Zee is a professor of neurology and director of the Northwestern Medicine Sleep and Circadian Rhythms Research Program and the lead author of the paper.
Fifty-four people were studied for a week and those who spent more time in light sometime during the morning hours (between 8am and noon) were leaner than those who were exposed during late afternoon or evening hours. The participants wore a wrist monitor that measured their light exposure and sleep patterns. The volunteers also kept a detailed log of everything they ate and drank during a seven-day period.
The authors also suggest that morning light’s blue color may be key.
“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 Zee to HealthLink.
This can also suggest some adverse implications for graveyard shift workers, who may not get a chance to benefit from natural light. However, bright artificial office lights do provide a similar dosage.
Standing in sunlight alone won’t help one lose weight, a healthy diet with exercise is vital too. And be sure to always use sunscreen.
S.C. Rhyne is a blogger and novelist in New York City. Follow the author on Twitter @ReporterandGirl, http://Facebook.com/TheReporterandTheGirl and visit her website at http://www.SCRhyne.com