As it turns out, sleeping with too much light in the room can significantly increase the risk of obesity, especially in women.
Recently, a British study, funded by the charity Breakthrough Breast Cancer and published in the American Journal of Epidemiology, looked at 113,000 women over a 40-year period. Researchers wanted to identify the root causes of breast cancer.
With breast cancer, obesity is a known risk factor for the disease so the research looked at the potential risk factors related to obesity. What they found was interesting: Greater exposure to light at night raised participants’ body mass index (BMI) and their overall waist size.
“Metabolism is affected by cyclical rhythms within the body that relate to sleeping, waking and light exposure,” lead researcher Anthony Swerdlow of London’s Institute of Cancer Research says. “The associations we saw in our study between light exposure at night and obesity are very intriguing.”
This isn’t the first time this sort of connection has been drawn. Researchers at Ohio State University discovered that mice exposed to a relatively dim light at night over eight weeks had a body mass gain that was about 50 percent more than other mice that lived in a standard light-dark cycle. The results of the study, published in the Proceedings of the National Academy of Sciences, suggest that mice living with light at night eat at times they normally wouldn’t.
Let’s face it there has been a worldwide epidemic of obesity in recent years. A February 2014 survey – conducted by the U.S. Centers for Disease Control and Prevention (CDC) and published in the Journal of the American Medical Association (JAMA) – revealed that while obesity rates among children decreased by 43 percent over the last 10 years, obesity increased dramatically among women aged 60 and over. Researchers made the discovery by looking at data provided to the CDC, which took samples from 9,000 Americans of all ages.
Interestingly, the CDC reported last year that only one in five American adults exercise enough. In fact, only 20 percent met the federal government’s physical activity guidelines. According to these guidelines, adults should participate in at least two and a half hours of moderate physical activity every week, or just one hour and 15 minutes of vigorous aerobic activity.
So how exactly does light every night create changes in metabolism? For the most part, light can disrupt levels of the hormone, melatonin, involved in the metabolic process. But it can also interfere with the expression of “clock” genes, which help to control when a person feeds and is active during the day.
Of course, it’s too early to say whether sleeping in the dark will help prevent obesity altogether. But the association between light exposure and metabolism is clear, and the research continues to come out in favor of keeping the potential for obesity at bay.
So remember, lights out! If you’d like to try another method to try to keep slim, this one should be an easy one.