University study means doctor’s orders may soon include, ‘Get Some Dark’
Lamps, TVs, and computers could be making you put on weight. At least that’s what a recent joint Israeli-American study has found.
Researchers have long highlighted the links between a lack of physical activity and bad eating habits with weight gain and obesity. But now scientists from Ohio State University and the Israel’s University of Haifa have found that exposure to artificial light at night may cause obesity, as well — regardless of food intake or exercise level —because it interferes with how the body marks time … in mice at least.
“Our study shows that watching TV at night can cause obesity, not only due to inactivity and overeating, but also because it upsets the body’s natural daily cycle,” Professor Abraham Haim, the head of the Center for Interdisciplinary Chronobiological Research at the University of Haifa said in a press release.
Haim said that exposure to artificial light at night bucks the body’s recognition of sunrise and sunset. This in turn upsets the biological clock and damages cyclical regulation of body cells, tissues, and organs.
The study compared how lab mice reacted to varying degrees of light for eight weeks. One group of mice was exposed to a “regular day,” of 16 light hours and 8 dark hours. A second group was not given any dark hours at all, and a third group was given 16 hours of daylight, followed by eight hours of dimmed light.
Although the mice were all given the same amount of food and exercise, those that didn’t have eight dark hours put on significantly more weight (12 grams), while those that had a “regular day,” (only 8 grams). Scientists also found that the mice exposed to dim light instead of the dark, ate more at night more than the mice living “regular days.”
In a separate experiment, the scientists limited the mice to eating only during daytime hours—normal mice chow time— and found that there was no difference between the groups in weight gain.
Haim said that the study strengthens earlier research showing that artificial light at night hampers the production of melatonin, a hormone the brain produces under dark conditions. The lack of melatonin interferes with the body’s cyclical functions, making the mice eat at abnormal hours.
The study was partially supported by the United States-Israel Binational Science Foundation.