Planet Earth

Is It Blue Light, Rather Than Darkness, That Makes Us Tired at Night?

80beatsBy Veronique GreenwoodJun 29, 2012 5:02 PM

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The color you see is a perceptual trick of your brain: it is not, no matter what your preschool teacher told you, an inherent physical property of that red apple or green leaf. The truth is that colorful objects just happen to be reflecting wavelengths of light that our brains interpret as specific colors. Do we all see those reflected wavelengths the same way? Because the experience of color vision is impossible to share, we simply don't know. It's quite possible that they're not. In fact, a certain subset of people may well see a hundred times as many colors of the rest of us

, but, because of the essentially privateness of color vision, have never realized that they are different. In a tour through recent research

 on the perception of color, Natalie Wolchover at Life's Little Mysteries also turns up another weird insight to add to the long list of strange things about color vision: It could be the blueness of light around twilight that makes us calm, and the yellowness of light around dawn that wakes us up, rather than brightness and darkness:

In a study detailed in the May issue of the journal Animal Behavior, [researchers] found that changing the color (or wavelength) of ambient light has a much bigger impact on the day-night cycle of fish than changing the intensity of that light, suggesting that the dominance of blue light at night really is why living things feel more tired at that time (rather than the fact that it's dark), and the dominance of yellow light in the morning is why we wake up then, rather than the fact that it's lighter.

That suggests that maybe it's yellow light, rather than bright light, per se, that we should be memorializing in verse. Note to modern Homers: perhaps that a "golden-fingered dawn" would be more appropriate than a rosy one.

Image courtesy of Robert J. Donovan / flickr

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