Monday, 24 June, 2019

Sleeping with artificial light at night associated with weight gain in women

Women exposed to artificial light at night were more likely to gain weight Women exposed to artificial light at night were more likely to gain weight
Gustavo Carr | 11 June, 2019, 23:26

In other words, exposure to light at night might represent a "constellation" of factors, including those related to unhealthy behaviors, "all of which could contribute to weight gain and obesity", the authors said.

Dozing off to late-night TV or sleeping with other lights on may mix up your metabolism and lead to weight gain and even obesity, provocative but preliminary USA research suggests.

Exposure to artificial light was positively associated with a weight gain or 5kg or more.

One of the factors pointed to by researchers is that light could suppress the sleep hormone melatonin and disrupt our circadian rhythms, according to ABC News chief medical correspondent Dr. Jennifer Ashton.

The researchers analyzed health and lifestyle data on almost 44,000 US women enrolled in an ongoing study seeking clues to causes of breast cancer. The participants, aged 35-74 years, had no history of cancer or cardiovascular disease and were not shift workers, daytime sleepers, or pregnant when the study began. The women were asked about their sleep habits and whether they slept in total darkness or in the presence of artificial light from a television or nightlight.

Lack of sleep has always been associated with obesity, but until now, the association between artificial light exposure while sleeping and weight gain has been unknown.

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The study researchers found that women who reported exposure to light at night while sleeping were more likely to gain weight and become obese over almost six years, compared with women who were not exposed to light at night.

Although the new findings aren't conclusive, reducing your exposure to light and night may not be a bad idea.

"Evolutionarily we are supposed to be sleeping at night, in a dark place", said lead author Dale Sandler, a scientist with the National Institute of Environmental Health Sciences, a division of the National Institutes of Health.

This sleep study comes on the heels of another study that found irregular sleep patterns, including not going to bed and waking up at the same time each day or getting different amounts of sleep each night, can put people at a higher risk for obesity, heart disease, hypertension, high blood sugar and other metabolic disorders. However, their findings did not change when analyses controlled for characteristics that may be associated with exposure to light at night.

Ms Sandler said she is confident that the added weight wasn't from things like snacking at night, because the analysis accounted for other variables that could have led to weight gain such as diet, physical activity and sleep duration. And the level of artificial light seemed to matter, Park said. It found that those who said they sleep with a TV or a light on in the room, gained 11 pounds or more, and had a body mass increase of about 10 percent over a 5-year period.