Don’t let the LED blue light blues get you down
TAKE A LOOK at some of the websites devoted to alternative medicine and you’ll likely come across headlines like, “The Dangers of LED & Blue Lights Will Blow Your Mind!” or, “LEDs: The Blue Light Risk,” or “Artificial lighting and the blue light hazard.”
These all stem from the belief that light in the blue part of the spectrum causes medical problems, everything from insomnia to promoting macular degeneration. And LEDs are supposedly a major source of blue light. Here’s what one website says on the subject: …..the most efficient LED bulbs of the day are almost exclusively emitters of predominantly blue light, though there are some exceptional products that mix all colors of the spectrum—but not many are available or affordable for house use.
Scary. And wrong, at least as far as we can determine. The pronouncements above come from a website that aligns itself with the herbalism. We tend to be skeptical of the alternative medicine crowd. So when we came across passages such as the one cited above, we decided to run our own tests of LEDs.
It’s not difficult to check claims about the wavelengths of LED output. To do so, we obtained a light meter designed for use by architects and room-lighting specialists who need to set light levels. To this we added an optical bandpass filter which only passes light in the bluewavelength range, about 450 to 490 nm.
To decide what LED bulbs to check, we went to Consumer Reports. As with other product categories, they rank LED bulbs. So for samples, we used five 60-W-equivalent LED bulbs Consumer Reports puts at the top of its rankings. They included bulbs from Sylvania, Philips, and EcoSmart (made by Feit). We also got hold of two incandescent 60-W bulbs, one with frosted glass, the other without.
For testing, we put each bulb in a completely dark room and measured its illuminance into the light meter sitting one-foot away, with and without the blue bandpass filter. That let us calculate the percentage of blue light output coming from from each of them.
We’ll cut to the chase. All of the 60-W equivalent LED bulbs we measured had less than 2% of their output in the blue light range. That’s a long way from being “emitters of predominantly blue light.” Moreover, both incandescent lights also had under 2% of their output in the blue wavelength range. And lest you think we tested super-pricey bulbs that few people can afford, one of our Sylvania bulbs cost a little over a dollar on Amazon.
To give the alternative medicine crowd the benefit of the doubt, we also tested an old LED bulb that came out before the DoE held its “L Prize” event in 2011. The L Prize is credited with kicking LED bulb development into high gear. So, we reasoned, perhaps bulbs made before then had the problematic blue light output. But the results were the same. We had one pre-2011 LED bulb on hand for testing. It, too, emitted less than 2% of its output in the blue wavelengths.
We aren’t done testing. The five bulbs at the top of the Consumer Reports list all put out relatively warm light. There are others whose light is colder, in the 3100 to 4500 K range. Eventually we’ll check a few of those as well. But so far, it looks as though you’re no worse off lighting your rooms with LEDs than with ordinary incandescent bulbs.
It’s best to take all those scary scenarios painted by alternative medicine websites with a grain of salt.
Filed Under: EE World Digital Issues, DIGITAL ISSUES, Filters (electrical) EMI • COTS • noise filters • shielding