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Obesity is a disease that can lead to several other health conditions, such as cardiovascular problems if left unmonitored. Health experts recommend people to maintain or lose weight via healthy dieting and physical activity. In a new study, researchers have identified another factor that could be contributing to obesity. The study led by the Institute of Cancer Research in London found that women who sleep with the lights on have a greater risk of gaining weight.

For this study, the team conducted a survey on 113,000 women. The survey collected information on the participants' body mass index (BMI), waist-to-hip ratio, waist circumference, sleeping habits and bedroom lighting. Specifically, the researchers asked the women to rate the amount of light under four situations, which were light enough to read, light enough to see across the bedroom but not to read, light enough to see one's own hand but not across the room and too dark to see your hand.

"In this very large group of people there is an association between reported light exposure at night and overweight and obesity," study author, Professor Anthony Swerdlow, said according to BBC News. "But there is not sufficient evidence to know if making your room darker would make any difference to your weight. There might be other explanations for the association, but the findings are intriguing enough to warrant further scientific investigation."

Even though the researchers did not find a cause-and-effect relationship, they provided a possible explanation for this link. They theorized that the presence of light during bedtime could disrupt the body's clock. Since the body is used to resting at night, having light at that time could change moods, physical strength and the body's food-processing system. Experts stated that since sleeping in darkness does not negatively impact health, people can try making their rooms darker and see if anything changes over time.

"People in general are not aware of the light present in their bedroom, I think people should assess their bedroom and see how easy it would be to make it darker," Professor Derk-Jan Dijk, from the Surrey Sleep Center. "Overall this study points to the importance of darkness."

The study, "The Relationship Between Obesity and Exposure to Light at Night: Cross-Sectional Analyses of Over 100,000 Women in the Breakthrough Generations Study," was published in the American Journal of Epidemiology.