Eliminating Light While Sleeping Could Reduce Obesity Risk in Women

Henrietta Brewer
June 13, 2019

After nearly six years of follow-up, women who slept with a television or light on in the room were 22 percent more likely to be overweight and 33 percent more likely to be obese than women who slept in total darkness without even a nightlight or the glow from an alarm clock.

"Although poor sleep by itself was associated with obesity and weight gain, it did not explain the associations between exposure to artificial light while sleeping and weight", said the study's corresponding author Dale Sandler, chief of the Epidemiology Branch at the NIEHS.

In addition, there was a 22% chance of becoming overweight and a 33% chance of becoming obese, she added.


The study questionnaire asked whether the women slept with no light, a small nightlight, light outside of the room, or a light or television on in the room.

The women were classified according to their level of exposure to artificial light at night (ALAN), which came from a variety of sources, from small nightlights or clock radios to light shining in from the street to televisions or room lights.

Globally, 1.9 billion adults are overweight or obese, according to the World Health Organization.


"Turning off the light while sleeping may be a useful tool for reducing a possibility of weight gain and becoming overweight or obese", said lead author Dr. Yong-Moon Mark Park. On top of this, a shorter sleep simply means more time awake, and therefore more time to eat. The association with having light coming from outside the room was more modest. "This study highlights the importance of artificial light at night and gives women who sleep with lights or the television on a way to improve their health".

"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. While a fatty eating routine and inactive way of life are the most regularly referred to clarifications for stoutness, some past research has likewise connected exposure to counterfeit light during the evening to an expanded danger of weight gain, analysts note in the study.

The research, which was published online June 10 in JAMA Internal Medicine, is the first to find an association between any exposure to artificial light at night while sleeping and weight gain in women.


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". "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.

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