Oct. 23 (HealthDay News) -- Exposure to too much light at night may cause depression, suggests a new study.

Ohio State University researchers found that mice kept in a lighted room 24 hours a day had more depressive symptoms than mice that had a normal day-night cycle. The study also found that mice that lived in a constantly lit room, but could take refuge in a dark tube when they desired, had fewer depressive symptoms than mice that couldn't get away from the 24-hour light.

"The ability to escape light seemed to quell the depressive effects," lead author Laura Fonken, a graduate student in psychology, said in a news release from Ohio State University.

The findings indicate the need to learn more about how artificial light affects humans, said study co-author Randy Nelson, a professor of neuroscience and psychology.

"Constant light with no chance of escape increased depressive symptoms," Nelson said in the news release. "The increasing rate of depressive disorders in humans corresponds with the increasing use of light at night in modern society. Many people are now exposed to unnatural light cycles, and that may have real consequences for our health," he added.

The study, presented at the annual meeting of the Society for Neuroscience held Oct. 17 to 21 in Chicago, is scheduled to be published in the Dec. 28 issue of the journal Behavioural Brain Research.

Research into the effects of artificial light on health "is important for people who work night shifts, and for children and others who watch TV late into the night, disrupting their usual light-dark cycle," Fonken said.

Nelson noted that hospital intensive care units are brightly lit throughout the night, which may have a negative effect on patients.

SOURCE: Ohio State University, news release, Oct. 21, 2009