Got a TV in the bedroom? Dozing with the lights on? You might want to flick the switch before falling asleep. According to a new study, this could be the reason why you’re gaining weight. Published Monday in the JAMA Internal Medicine, the National Institutes of Health report isn’t concrete proof but builds on other evidence that artificial light messes with our metabolism. Looking at health and lifestyle data from nearly 44,000 U.S. women, researchers found that those who slept with TVs or lights on gained at least 11 pounds over five years and were 30 percent more likely to become obese. Speaking about the study, lead author Dale Sandler said, “Evolutionarily we are supposed to be sleeping at night, in a dark place,” noting, “It’s much more important than people realize for a whole variety of health reasons.” Do you watch TV in bed or fall asleep with the lights on? Have you found that it affects your sleep? What changes have you made to get better sleep?