" The bright blue light of flat, rectangular touch screens, fans, and displays may be appealing from an aesthetic perspective (more on that below), but from a health standpoint, it is fraught with problems. Blue light inhibits the production of melatonin, the hormone that regulates our sleep cycles. Blue light before bedtime can wreak havoc on our ability to fall asleep. Harvard researchers and their colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light, versus exposure to green light of comparable brightness. They found that blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours compared with 1.5 hours). And worse, it’s been linked in recent studies to an increased risk of obesity and some cancers.
Thanks to the rapid growth of connected devices and digitized appliances, blue light is now flooding into our lives in places where we’re most vulnerable. It’s why, for instance, when we stumble into the kitchen late at night for some water, we’re guided by the illumination from the touchscreen on our refrigerator–and the after-image of the screen leaves us half-blind, and once back in bed, half-awake. "
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