The Bright Blue Lights of LEDs: Friend or Foe?

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The arrival of highly efficient LED lighting offering more than 100 lumens per watt, and the dramatic fall in LED prices over the past three years has led to a single minded focus on energy savings and rebates, life-time cost and ROIs of under a year. LED lighting retrofits have become basically free. With this remarkable incentive, LED lighting installations are projected to exceed 50% of the market before 2020.   This amazing growth in efficiency and energy savings is wonderful, but there is another side that’s not so amazing or wonderful. 

The LEDs emit blue light wavelengths, which suppress melatonin at rates five times greater than bulbs that give off warmer “orange-yellow” light, like incandescents.

Harmful effects of blue light

  • Suppressing melatonin, a hormone that naturally fights cancer.  Harvard researchers and their colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light to exposure to green light of comparable brightness. The blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours).  In 2007, the WHO organization decreed that shift work is a risk factor for breast cancer.  In 2009 the Danish began to compensate some female shift workers with breast cancer.
  • An out of sync circadian rhythm can cause disease. - Now researchers are finding increasingly that an out-of-phase circadian rhythm is a health hazard. “Maintaining synchronized circadian rhythms is important to health and well-being,” says Dieter Kunz, director of the Sleep Research and Clinical Chronobiology Research Group at Charité–Universitätsmedizin Berlin. “A growing body of evidence suggests that a desynchronization of circadian rhythms may play a role in various tumoral diseases, diabetes, obesity, and depression.”


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