What colour light should a lightbox produce? White, blue, full-spectrum?

There’s rather a kerfuffle going on amongst lightbox manufacturers as to what is the correct colour for bright light therapy.  Older models of lightboxes all used white fluorescent light, and I think that what is going on is mainly about the longer-established manufacturers trying to hang onto the market, while the new ones are trying to persuade customers that their exciting new product is superior.  So on one side you have old-fashioned white lightbox manufacturers baying that blue light will ruin your eyes, and on the other you have blue lightbox manufacturers claiming that blue light is all that matters.

From all the research I’ve read, it does seem that blue light is the most effective bandwidth.  Blue light is, of course, contained in white light, and even the brightest lightbox will not be as bright as outdoor sunlight.  If thirty minutes in front of a little lightbox was enough to wreck everyone’s vision, we’d all be blind from the sun by now, even with modern indoor living.  Psycheducation.org has written an excellent article on the purported dangers of blue light, concluding that unless you are at high risk of macular degeneration, you don’t need to worry, and to be sensible and not stare directly at your lightbox.

This spectrograph was produced by Apollo Health, the former manufacturers of the first blue lightbox, the GoLite, so it’s not from an unbiased source.  However, all the research I’ve read agrees that 470nm or thereabouts is the most effective bandwidth for affecting the circadian clock, and I’ve seen several spectrographs of fluorescent light (which is the  “standard full-spectrum” in this graph) that look the same.  Fluorescent light is spiky, which is apparently why it’s so harsh on the eyes, and even the full-spectrum versions don’t peak at 470nm.  Presumably this is why fluorescent lightboxes are a great deal larger than LED lightboxes and require longer treatment times.

Something interesting about LEDs is that the blue ones all seem to peak around 470nm naturally (warning: the page has lots of images and takes a long time to load).  This is why I suspect that using a standard blue LED bulb may not be as strong as a fancy lightbox, but it’s the right type of light and if used for longer, may have the same effect.  Typical white LEDs contain a broader bandwidth of light overall, but they turn out to peak around 470nm too (also a long page).  Here’s a typical example of a white LED bulb.

Some lightbox manufacturers claim that their LEDs are “blue-enriched white”, but frankly I think that they’re perfectly ordinary LEDs, the manufacturers are just cashing in on the fact that they happen to peak in the blue bandwidth.  (The advertising shenanigans of light therapy manufacturers can drive you demented at times.)

This means that white LEDs produce a cold light that most people don’t particularly like for domestic lighting, but it makes them ideal for bright lightboxes.  I’ve concluded that while blue light is the most effective, white LEDs are so close behind that you may as well choose your lightbox based on your personal preferences.  Some people find the blue light to be softer and less disruptive, other people find that they need white light so that they can look at colours properly (I once made the mistake of trying to do some embroidery with my GoLite on, and had to unpick it all afterwards as I’d picked up the wrong coloured threads), and a few people, such as my partner, just can’t get on with coloured light.  Choose according to your visual comfort and the other factors involved in choosing a lightbox, such as price, overall product quality and the various features that a lightbox can have.

If you prefer fluorescent lightboxes, there is the question of whether to go for normal or full-spectrum.  As far as I can tell, it doesn’t make any difference therapeutically, so go for whichever light you find to be most comfortable for your eyes, if you can even tell the difference.


Images courtesy of the LED Museum.

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