The Los Angeles Times reports on a study published in PLoS One that has found that exposure to morning sunlight may be an important regulator of BMI. 54 volunteers wore a wrist monitor to determine the amount of sunlight to which they were exposed and the amount of sleep they got. They were also asked to report on diet and exercise. Researchers found that even after controlling for “demographic factors like age and gender, the amount of sleep and exercise volunteers got, and the season of the year,” the best predictor of BMI was MLiT, or mean light timing above threshold; the more morning light exposure, the lower a person’s BMI. Researchers believe that the effect is caused by the high amount of blue wavelength light in morning light which has been shown to be an important regulator of circadian rhythm and metabolism.