Color of nightlight can affect mood
Feeling “blue” may stem from using a nightlight that emits a blue glow, according to research published in The Journal of Neuroscience. Researchers from Ohio State University concluded that our moods can be affected by color of the nighttime light we expose ourselves to, and that switching from blue to red could reduce your chances of feeling depressed.
The scientists found that blue light caused the most depressive behavior in hamsters, and white light (from normal light bulbs) had similar but less severe effects. Red light produced fewer signs of depression. The only scenario that produced better mood measures in hamsters than the red light was total darkness.
The hamsters had four weeks of exposure to each hue of light; no light, dim red right, dim white light, and dim blue light. Scientists measured “depression” in the hamsters by observing behaviors, such as sugar-water consumption. If the hamster drank less than normal, it was considered a depressed behavior. They also analyzed the hippocampus of the hamster brains to study their dendritic spines-- hairlike bits on brain cells that send chemical messages from cell to cell--as they have been linked to depression when they are a lower density. The researchers found that the hamsters exposed to blue and white light had dendritic spines of lower density than the ones who had been exposed to red light or no light.
Researchers say that their findings could be significant for humans, particularly who work the night shift and are exposed to artificial light. Photosensitive cells in the retina can detect light and send messages to the brain, which regulates circadian rhythm and could affect mood. These cells may be less sensitive to red light wavelengths and more sensitive to blue light wavelengths. The researchers suggest switching to red lights for night shift workers.