Sunday, 15 September, 2019

Exposure to artificial light at bedtime linked with weight gain in women

Keeping Your TV on at Night May Lead to Weight Gain Credit Shutterstock
Gustavo Carr | 13 June, 2019, 23:11

Those who reported sleeping at night in a room with a television on or a light were more likely to gain at least 4.9 kgs over about five years than those who slept in darkness.

"As the authors mention, you can't point directly to causality between bedroom light exposure at night for a sleeping individual and weight gain but I think this is definitely a step in that direction", he said.

There was also a 22-percent chance of becoming overweight and a 33-percent chance of becoming obese or having too much body fat.

The researchers note that exposure to artificial light while sleeping might reflect other unhealthy behaviours, such as a sedentary lifestyle, and socioeconomic disadvantage.

Artificial light has been shown to hamper sleep quality, and that's one of the reasons why blue-light-dimming features have crept into our mobile devices and computers.

Turn off the lights on your way out. On top of this, a shorter sleep simply means more time awake, and therefore more time to eat.

A BMI between 18.5 and 24.9 is considered healthy, while 25 to 29.9 is overweight, 30 or above is obese and 40 or higher is severely or morbidly obese.

So do you need to kick the habit and cut the lights?

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In analyzing the health and lifestyle data on almost 44,000 USA women enrolled in an ongoing breast cancer study, scientists discovered that those who reported sleeping at night in a room with a television on or a light were more likely to gain at least 11 pounds over about five years than those who slept in darkness.

The new findings, published today (June 10) in the journal JAMA Internal Medicine, suggest that "reducing exposure to artificial light at night while sleeping might be a useful strategy to prevent obesity", study lead author Dr. Yong-Moon Park, a postdoctoral fellow at the National Institute of Environmental Health Sciences (NIEHS), and senior author Dale Sandler, chief of the NIEHS's Epidemiology Branch, told Live Science in an email. "It seems reasonable to advise people not to sleep with lights on", Park and Sandler said.

Animal research and smaller studies in humans have linked prolonged light exposure with weight gain.

"There was a dose response, in that the more light in the room the stronger the association", Sandler said.

Professor Malcolm von Schantz, from the University of Surrey, commented on the study, saying: 'The findings make ideal biological sense.

Artificial light exposure at night from things like streetlights, storefronts, and even cell phone use, for example, can disrupt the natural light-dark cycle of circadian rhythms and suppress the release of the sleep hormone melatonin.

'These new findings won't change the advice to maintain good sleep hygiene, and avoid light and electronic distractions in the bedroom, but they add further strength to the case for this advice'.