Light at Night May Raise Depression Risk, Study Suggests

Constant exposure to light at night can cause depression, a new study in animals suggests.

In the study, hamsters exposed to dim light at night for four weeks showed signs of depression, such as less interest in drinking sugar water they usually enjoy, compared with animals not exposed to light at night, the study found.

The findings suggest exposure to artificial light at night may have contributed to the rising rates of depression over the last 50 years, said study researcher Tracy Bedrosian, a doctoral student in neuroscience at Ohio State University.

"The advent of electrical lighting permitted humans to stray from natural day-night cycles," potentially disturbing our biological rhythms and leading to changes in behavior, Bedrosian said.

But the study also suggests good news: the negative effects of light at night were reversed in the animals after just two weeks of normal lighting conditions, the researchers said.

"People who stay up late, in front of the television and computer, may be able to undo some of the harmful effects just by going back to a regular light-dark cycle and minimizing their exposure to artificial light at night," Bedrosian said.