There is actually a lot of weight in what the article has to say regarding the differences between various white light sources, particurlarly LED's vs incandescent and/or sunlight., and their research is very likely accurate and relative.
The piece you probably don't understand is that "white" light as supplied to up by our sun (or an incandescent lamp) is a continuous spectrum of light comprised of all colors or wavelengths of light..
These light sources are called "black bodies", which basically describes black things that are so hot that they emits visible (and invisible) light... The ratio of bluish light to reddish light that they emit has to do with how hot they are- that's where the kelvin temperature comes in. Hotter (higher kelvin temperature) equates to light that is visibly bluer, but in all cases if you put the light from a black body source through a prism, you'll see a continuous rainbow of all colors making up that "white" light.
That's what we as humans have gotten used to over the last few million years, and what our bodies are programmed to react to.
LED's on the other hand, are devices that emit very specific, almost single
wavelengths of light. For example take an incandescent lamp and stick a red gel over it to make red light.
If you put that light through a prism you will see a broad spectrum of light. But put the light from a red LED that "looks" to be the same color through that prism and you'll see only one narrow band of color. Take a look at this graph... the yellow line shows the spectrum of a light bulb filtered by a red gel, which is a fairly constant spread of wavelengths between 600 and 750nm. But the LED which "looks" the same is only a very narrow band of light centered around 635nm or so.
That is what these guys are talking about.
Light that is perceived as white, made with LED's, is actually missing most of the wavelengths that a similar white from the sun would contain. All you have to do to make a human think light is white is add narrow bands of red, green, and blue together. Interestingly you can also create a good looking "white" light using only blue and yellow... there are actually quite a few combinations of narrow bands that will look white to a human and still be missing most of what the white light from the sun or an incandescent light contains.
It's kinda like perfumes. If you have a good smelling rose and you analyze the actual chemical constituents of it, you'll find that there are 5-6 major chemicals that make up roses' scent, along with almost three hundred minor chemicals.
To make a synthetic rose scent, all you need to do is add those 5-6 major chemicals together in the right ratios, and leave out the hundreds of minor chemicals. If you smell the two, they both smell like roses but there's something definitely different about that synthetic, and usually not as good. The "finesse" of the scent has been eliminated.
This chart shows the wavelengths of various lights that we're used to seeing, and other than the bar-code laser, most of the others can roughly be perceived by us as white light.
Its interesting to see how very different they are!
As the article states, LED white light is actually VERY blue. There is no such thing as an actual white LED... what they are is a very intense blue LED with some phosphor painted over it. The blue light excites the phosphor to glow and produce yellowish light, and that plus what blue leaks through adds up in our eyes to look white. "White LED's" can also be created by sticking a red led chip, a blue led chip and a green led chip into the same package. The result is an led that allows you to create any perceptual color, just like a TV or computer monitor does, by changing the ratios of light coming from those three chips.
Here's a couple of good articles on color Led's and light if you're interested... also where I got the graphs...http://tinyurl.com/775bsuchttp://www.olympusmicro.com/primer/lightandcolor/lightsourcesintro.html
The LED industry has all the same problems... how to get these narrow band devices to fake us out and make us think it looks like real white light.
In the end, as the article states, we may get faked out and think what we're seeing is white light, but our melatonin sensors don't. It's still not pinned down if this is good or bad for us, but it is real, and it probably has repercussions in the long run.
For what it's worth, I have changed most of my house and all of my shop to white LED lighting. I think it's fantastic... science or not, I get along fine with it!!