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Our homes glow at night. Light bulbs, TVs, and now computers, e-readers, tablets and smartphones expose people to an increasing amount of light after dark. And the color of that light may influence mood and brain function. That’s according to a study in the Journal of Neuroscience. [Tracy A. Bedrosian et al, Nocturnal Light Exposure Impairs Affective Responses in a Wavelength-Dependent Manner] Researchers looked at the role of specialized photosensitive cells in the retina. The cells, called ipRGCs, are responsible for regulating circadian rhythms. And recent evidence suggests these cells may also play a role in mood and cognition. To test how nocturnal lighting color affects mood, the researchers exposed hamsters to nighttime conditions of no light, red light, white light or blue light for four weeks each. Hamsters exposed to red light at night had the fewest brain changes associated with depression in humans, while blue and white light had the worst effects on mood. So late-night work email may not be the only thing ticking you off—the blue glow of your machine may also be getting you down. The best bet: shut down and get some shuteye. —Allie Wilkinson [The above text is a transcript of this podcast] Follow Scientific American on Twitter @SciAm and @SciamBlogs.Visit ScientificAmerican.com for the latest in science, health and technology news.© 2013 ScientificAmerican.com. All rights reserved.
