Medical Xpress reports on the colorful work of Ohio State U neuroscientists who have studied the effects of nightlights on depression:
In a study involving hamsters, researchers found that blue light had the worst effects on mood-related measures, followed closely by white light.
But hamsters exposed to red light at night had significantly less evidence of depressive-like symptoms and changes in the brain linked to depression, compared to those that experienced blue or white light.
The only hamsters that fared better than those exposed to red light were those that had total darkness at night.The findings may have important implications for humans, particularly those whose work on night shifts makes them susceptible to mood disorders, said Randy Nelson, co-author of the study and professor of neuroscience and psychology at The Ohio State University.
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“Light at night may result in parts of the brain regulating mood receiving signals during times of the day when they shouldn’t,” said co-author Tracy Bedrosian, a former graduate student at Ohio State who is now a postdoctoral researcher at the Salk Institute. “This may be why light at night seems to be linked to depression in some people.”
What people experience as different colors of light are actually lights of different wavelengths. The [photosensitive cells in the retina called] ipRGCs don’t appear to react to light of different wavelengths in the same way.
“These cells are most sensitive to blue wavelengths and least sensitive to red wavelengths,” Nelson said. “We wanted to see how exposure to these different color wavelengths affected the hamsters.”