The U.S. suffers an epidemic of depression. Every year, about 9 percent of us suffer clinical depression. Our addiction to lighting up the night may be making the problem worse. Lab studies show that chronic exposure to light at night can lead to depressive symptoms.

Researchers at Ohio State have found that nighttime lighting (lights, video screens, etc.) causes changes in a part of the brain called the hippocampus that can derail mood. But you can reverse this process. Near bedtime, turn off your lights and stay away from video screens, and your depressive feelings may dissipate. But the research at Ohio State shows that cutting back on nighttime lighting may take a couple of weeks to assuage your sad feelings.

“The good news is that 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,” said lead author Tracy Bedrosian. “That’s what the results we found in hamsters would suggest.”