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Lift depression by using this color of nightlight

Teresa Tanoos's picture
New study finds red light helps alleviate depression

If you’re feeling blue, changing your nightlight to red could help, according to a study published in The Journal of Neuroscience. Researchers involved the study set out to determine how different colors and hues might affect mood, and here’s what they found:

1. Blue light elicited the worst response against mood-related measures;
2. White light had similar effects but less severe; and:
3. Red light produced decidedly fewer signs of depression.

Using hamsters as test subjects, researchers also found that total darkness was the only light setting that triggered greater mood levels than red light.

For the study, they exposed the hamsters to 4 weeks each of four different lighting conditions as follows: 1) no light; 2) dim red light; 3) dim white light similar to normal light bulbs; and 4) dim blue light.

The researchers then collected information, such as sugar-water consumption, to check for “depressive-like symptoms” in the hamsters. In other words, if the hamsters drank a lower than normal amount of sugar water, it was considered evidence of a mood shift.

The hamsters that were exposed to total darkness drank the most sugar-water, whereas the ones exposed to white or blue light drank the least. Moreover, the researchers also examined the hippocampus of the hamsters' brains to see the density of their dendritic spines, which send chemical messages from cell to cell.

Professor Randy Nelson, co-author of the study, pointed out that depression has been linked to dendritic spines with a lowered density, and the hamsters exposed to blue or white light had dendritic spines that were significantly lower in density than the hamsters exposed to total darkness or red light.

"In nearly every measure we had, hamsters exposed to blue light were the worst off, followed by those exposed to white light. While total darkness was best, red light was not nearly as bad as the other wavelengths we studied," explained Nelson says.

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So what do these findings in hamsters have to do with humans?

A lot, according to the researchers, who say their findings are important for humans, especially for night-shift workers and others exposed to artificial light at night.

Humans have special photosensitive cells in the retina, called ipRGCs, which can detect light and send messages to the brain. The researchers say these cells contribute to regulating the body's circadian rhythms, and they reference other studies that support how such cells also send messages that can affect one’s mood.

"Light at night may result in parts of the brain regulating mood-receiving signals during times of the day when they shouldn't. This may be why light at night seems to be linked to depression in some people," said Tracy Bedrosian, co-author of the study.

Put simply, different colors are no more than lights with varying wavelengths, say the researchers. And ipRGCs are more sensitive to blue wavelengths than red wavelengths, which may explain why the hamsters were affected by the varying colors.

The findings, points out Prof. Nelson, "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."

The researchers conclude that shift workers and others could benefit from limiting their light at night.

"If you need a night light in the bathroom or bedroom, it may be better to have one that gives off red light rather than white light," added Bedrosian.

Nocturnal light exposure impairs affective responses in a wavelength-dependent manner, Tracy A. Bedrosian, Celynn A. Vaughn, Anabel Galan et al, The Journal of Neuroscience, 7 August 2013, 33(32): 13081-13087. DOI: 10.1523/JNEUROSCI.5734-12.2013