Written by Ohio State University Tuesday, 12 October 2010 14:33
COLUMBUS, Ohio—Persistent exposure to light at night may lead to weight gain, even without changing physical activity or eating more food, according to new research in mice.
Researchers found 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.
“Although there were no differences in activity levels or daily consumption of food, the mice that lived with light at night were getting fatter than the others,” said Laura Fonken, lead author of the study and a doctoral student in neuroscience at Ohio State University.
The study appears this week in the online early edition of the Proceedings of the National Academy of Sciences.
If the mice are not less active or eating more, what’s causing the bigger weight gain? Results suggest that mice living with light at night eat at times they normally wouldn’t.
In one study, mice exposed to light at night—but that had food availability restricted to normal eating times—gained no more weight than did mice in a normal light-dark cycle.
“Something about light at night was making the mice in our study want to eat at the wrong times to properly metabolize their food,” said Randy Nelson, co-author of the study and professor of neuroscience and psychology at Ohio State.
If these results are confirmed in humans, it would suggest that late-night eating might be a particular risk factor for obesity, Nelson said.