Feeling blue has taken on a whole new meaning.
A recent study on hamsters found that blue light has the worst effect on mood, followed by white light.
However, red light was the least disruptive; the hamsters exhibited less depressive-like symptoms.
The findings are significant to humans, particularly for those working night shifts, as they are most exposed to white light at night.
Read: Saving the night: Light pollution a serious concern for human health and wildlife
“Our findings suggest that if we could use red light when appropriate for night-shift workers, it may not have some of the negative effects on their health that white light does,” co-author of the study, Randy Nelson said.
The research studied the instrinsically photosensitive retinal ganglian cells (ipRGCs), cells in the eyes, which don’t play a part in vision, but instead detect light and send messages to the part of the brain that regulates our circadian rhythm. Our circadian rhythm is what helps tell our body when to stay awake and when to sleep.
“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.”
The researchers were able to determine depressive behaviour in the hamsters by monitoring how often they drank sugar water – something they enjoy – as well as examining the hippocampus region of their brains.
Hamsters that spent a night in dim blue or white light had a reduced density of dendritic spines – hairlike growths on brain cells that are used to send chemical messages to each other. A lowered density has been linked to depression, Nelson said.
The study appears in the Aug. 7, 2013 issue of The Journal of Neuroscience.
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