Much of our sleep patterns – feeling sleepy at night and awake during the day – are regulated by light and darkness. Light is the most powerful regulator of our biological clock. So what happens if you get too much light at night? According to EurekAlert, a recent study at Ohio State University looked at mice housed in a lighted room for 24 hours a day and mice housed in a room with a normal light-dark cycle. The study found that mice exposed to 24-hour light exhibited more symptoms of depression than the other mice. Researchers believe the results of the study, which was presented at the Oct. 21 annual meeting of the Society for Neuroscience, show that more research should be conducted on the effect of artificial light on people. "The increasing rate of depressive disorders in humans corresponds with the increasing use of light at night in modern society," study co-author Randy Nelson, a professor of neuroscience and psychology at Ohio State University, told EurekAlert. "Many people are now exposed to unnatural light cycles, and that may have real consequences for our health."