New Study Shows a Link between Bright Bedroom and Obesity

Rebecca Lewis June 03, 2014

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A team of researchers at the Institute of Cancer Research in London found women had larger waistlines if their bedroom was "light enough to see across" at night.

In the study, 113,000 women were asked to rate the amount of light in their bedrooms at night – whether it was light enough to read, light enough to see across the room, but not read; light enough to see your hand in front of you, but not across the room; or too dark to see your hand or you wear a mask.

Their answers were compared to several measures of obesity.

Results showed that body Mass Index, waist-to-hip ratio and waist circumference were all higher in women with lighter rooms.

No sufficient evidence

Whilst the new study involved a large sample, researchers cautioned there is not enough evidence to advice people to buy thicker curtains or turn off lights. "There might be other explanations for the association, but the findings are intriguing enough to warrant further scientific investigation." Prof Anthony Swerdlow, from the Institute of Cancer Research, told the BBC.

One possible reason is that the light is disrupting the body clock, which stems from our evolutionary past when we were active when it was light in the day and resting when it was dark at night.

Light alters mood, physical strength and even the way we process food in a 24-hour cycle.

Artificial light is known to disrupt the body clock by delaying the production of the sleep hormone melatonin.

Prof Derk-Jan Dijk, from the Surrey Sleep Centre, said there would be no harm in trying to make bedrooms darker.

"People in general are not aware of the light present in their bedroom, I think people should assess their bedroom and see how easy it would be to make it darker." he told BBC.

Street lights, some alarm clocks and standby lights on electrical equipment such as televisions could light a room, he said.

"Overall this study points to the importance of darkness," he concluded.

The study was part of an on-going research to examine the risk factors for breast cancer, of which obesity is known to increase the risk of the disease.

"It’s too early to suggest that sleeping in the dark will help prevent obesity, a known risk factor for breast cancer, but the association is certainly interesting.” Dr Matthew Lam from the charity said.

"Whilst we are learning more and more each day about the environmental, genetic and lifestyle factors that affect breast cancer risk, it is not yet possible to predict who will get breast cancer, and for women who have been diagnosed with the disease, we can’t yet say what caused it."

The findings were published in the American Journal of Epidemiology.

Source of this article:

Light bedrooms ’link to obesity’