If you’ve gained weight and don’t know why, turn off the night lights. According to a new study, seeing light at night could trigger biological changes that cause weight gain.
Is Light at Night a Cause of Weight Gain?
When researchers exposed mice to dim light at night for two months, the formerly slender rodents gained fifty-percent more weight than mice that slept in total darkness. Interestingly, even when researchers gave the “chubby” mice less food and forced them to do regular exercise, it didn’t lower their weight to the level of the mice that slept in a dark room.
Although a mouse study doesn’t necessarily show a relationship between night lights and weight gain in humans, there is some evidence that exposure to light at night increases the risk of obesity in people too. According to research, people who work night shifts where they’re up and about at night and sleep during the day have a higher risk of obesity.
Why Would Light at Night Cause Weight Gain?
It isn’t clear why light at night causes weight gain, but researchers believe that light hitting the eye at a time when an animal or human should be sleeping triggers changes in hormones that signal when and how much to eat – and also indirectly affects metabolism.
One hormone called melatonin that’s produced by the pineal gland in the brain helps to regulate the sleep-wake cycle – as well as eating patterns in humans and animals. Since most melatonin releases occurs in darkness, animals exposed to light at night will have lower levels of melatonin.
Night eaters, people who eat large amounts of food in the evening and usually gain weight from this practice, also have lower levels of melatonin. This shows how melatonin, a hormone that’s suppressed by light at night, could play a role in weight gain.
Do Night Lights Cause Weight Gain: The Take-Home Message?
Exposure to light at night causes weight gain in animals, and there’s some evidence that it does in humans too. There are other good reasons to cut off the night lights. As mentioned, exposure to light at night reduces melatonin levels, which may increase the risk of certain types of cancer.
The bottom line? If you can’t get your bedroom completely dark, get a sleep mask to block out light at night. Not only will you have an easier time sleeping, but it may help to keep the weight off.
Medical News Today. “Light At Night Linked To Weight Gain Perhaps Due To Shift In Eating Times”
International Journal of Obesity (2003) 27, 1353′”1358.