- Exposure to dim lights when it should be dark may contribute to depression.
- Light exposure at the wrong times of day has been linked to all sorts of health problems.
- To boost your mood, it might help to give yourself some solid hours of true darkness at night.
Basking in the glow of your TV, smart phone or living room lights late into the night may put you at risk for depression, suggests a new study.
The research, which involved hamsters, adds to growing evidence in both animals and people that exposure to even dim lights at night can lead to all sorts of negative health consequences, including breast cancer, sleep disorders and weight gain.
"We've set up a link between exposure to light at night with depression in these animals," said Tracy Bedrosian, a doctoral student in neuroscience at The Ohio State University in Columbus. "If it does apply to humans, people might want to think about getting dark shades, not leaving the TV on all night long, and making sure to give themselves darkness when they go to sleep."
Major depression has grown more common in recent decades, Bedrosian said. And while there is probably no single reason for the trend, researchers suspect that light disturbances may play a part.
That suspicion is based, in part, on the simple observation that people today are exposed to far more sources of artificial light at night than they were 100 years ago. More people have computers in their bedrooms. More people fall asleep with the TV on.
Studies have also found that people who work night shifts have higher rates of mood disorders compared to people who sleep when their bodies are supposed to sleep.
To test the link between light and depression, Bedrosian and colleagues split a group of 16 hamsters into two groups. All of the animals spent 16 hours a day under bright lights. During the rest of the time, eight of the hamsters were given true darkness. The other eight were exposed to dim lights, at a level similar to the glow of a TV in a dark room.