Sleeping with Lights On can Increase Obesity Risk: Study

People who sleep with the lights on are more likely to become obese, according to a study.

British researchers found the level of light exposure during night sleep is associated with an increase in the body mass index (BMI) and waist measurement in women. Earlier experiments on animals have linked light exposure to changes in circadian cycles and metabolism, leading to weight gain and obesity.

Obesity is a key factor for various illnesses and diseases, especially breast cancer. Recently, the Institute of Cancer Research in London used data from the Breakthrough Generations Study involving more than 100,000 women and followed them for 40 years. Experts conducted this research to examine if obesity is a definite risk factor for breast cancer.

Their analysis revealed that the level of light exposure was directly related to weight gain in participants. This was observed even after adjusting other influencing factors for obesity like physical activity, hours of sleep and having young children.

"Metabolism is affected by cyclical rhythms within the body that relate to sleeping, waking and light exposure. The associations we saw in our study between light exposure at night and obesity are very intriguing, "said Anthony Swerdlow, study author and professor of epidemiology at the Institute of Cancer Research, reports the Telegraph.

However, the authors were unable to confirm the connection between excess weight gain and sleeping at night with the lights on. They add that this finding provides basis for further investigation.

"Because all the information was collected at the same time, we cannot tell the sequence of events, but the associations we found are consistent with previous research examining light exposure and metabolism, and further investigation is needed," said Emily McFadden, study author and visiting researcher at the Institute of Cancer Research, reports the Telegraph.

The authors are unsure if sleeping in the dark can stall obesity and cancer causing mechanism in the body.

The research was funded by the Breakthrough Breast Cancer and The Institute of Cancer Research (ICR), along with grants received from NIHR Biomedical Research Centre at The Royal Marsden NHS Foundation Trust. More information is available online in the American Journal of Epidemiology.