COLUMBUS, Ohio -- Chronic exposure to dim light at night can lead to depressive symptoms in rodents -- but these negative effects can be reversed simply by returning to a standard light-dark cycle, a new study suggests.
While hamsters exposed to light at night for four weeks showed evidence of depressive symptoms, those symptoms essentially disappeared after about two weeks if they returned to normal lighting conditions.
Even changes in the brain that occurred after hamsters lived with chronic light at night reversed themselves after returning to a more normal light cycle.
These findings add to the growing evidence that suggest chronic exposure to artificial light at night may play some role in the rising rates of depression in humans during the past 50 years, said Tracy Bedrosian, lead author of the study and doctoral student in neuroscience at Ohio State University.
"The results we found in hamsters are consistent with what we know about depression in humans," Bedrosian said.
But the new study, published online in the journal Molecular Psychiatry, also offers some hope.
"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," Bedrosian said. "That's what the results we found in hamsters would suggest."
Bedrosian conducted the study with Ohio State colleagues Randy Nelson, professor of neuroscience and psychology, and Zachary Weil, research assistant professor in neuroscience.
This study is the latest in a series out of Nelson's lab that have linked chronic exposure to light at night to depression and obesity in animal models.
The new study found that one particular protein found in the brain of hamsters -- and humans -- may play a key role in how light at night leads to depression.<
|Contact: Tracy Bedrosian|
Ohio State University