The researchers, from the National Institute of Environmental Health Sciences in the U.S., followed 43,722 women aged between 35 and 74 years old, over a period of at least five years. They were also about 30% more likely to become obese.
So do you need to kick the habit and cut the lights?
The study analyzed the sleeping habits of almost 44,000 women in the United States.
Getting enough quality sleep every night is a tip at the top of any healthy living checklist, and lack of sleep has indeed been associated with a variety of conditions including obesity. "It seems reasonable to advise people not to sleep with lights on", Park and Sandler said. Women who slept with a mask on or reported no light while sleeping were classified as experiencing no artificial light exposure.
One limitation of the study is that researchers relied on women to report their own height and weight.
- Women who sleep with the television on or with the presence of other artificial light during the night may be at higher risk of weight gain or developing obesity, according to a group of researchers at the National Institutes of Health. According to a new study, this could be the reason why you're gaining weight.
The researchers found that women who slept with a slept with a light or television on in the same room were 17% more likely to gain 5kg or more over the next five years.
Scientists in the United States have found that sleeping with artificial light at night is linked with weight gain in women, and turning off lights at bedtime may reduce their chances of becoming obese.
Poor sleep as a standalone factor has been proven to be associated with obesity and weight gain, but Dale Sandler, Ph.D. and a co-author of the research, said, "it does not explain the associations between artificial light exposure during sleep and weight gain".
Commenting on the paper, Malcolm von Schantz, a professor of Chronobiology at the University of Surrey in Britain said: "What is novel with this paper is that it is a longitudinal study comparing the weight of the same individuals at baseline and more than five years later".
"Even with the lights off, our bedrooms are often aglow at night from luminous clocks, light-emitting diodes from electronic devices, and outside lighting that seeps through porous curtains and shades", Gangwisch said. "We know from experimental studies in people that light at night affects our metabolism in ways that are consistent with increased risk of metabolic syndrome", he said.