Posted tagged ‘Full-spectrum light’

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

January 26, 2010

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.

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Images courtesy of the LED Museum.

Bright light therapy

January 26, 2010

This is best known for treating Seasonal Affective Disorder, where it has been found to be as effective as anti-depressants, although the most effective treatment of all is to combine light therapy with anti-depressants.  What is less well-known is that bright light therapy is almost as effective in non-seasonal depression and is extremely useful for circadian rhythm disorders.

The main myth about bright light therapy is that it’s about full-spectrum lighting. It isn’t.  There are quite a few myths about light therapy which have been set up by rivalrous product manufacturers, and this one is an attempt to sell certain fluorescent lightboxes by claiming that they are in some way better than the others, which has somehow turned into the myth that all you need is a standard full-spectrum bulb.  The most effective wavelength for resetting the circadian clock is 470nm, blue light, so you need either blue light or white light which has plenty of blue in it.  (A couple of manufacturers favour green light for rather complicated reasons which you can read about here, where it’s concluded that they’re not worth trying unless you are at high risk of maculuar degeneration.)  The other important thing is the intensity of the light.  When a traditional fluorescent lightbox is used, 10,000 lux is preferred, though there are a few models around which use 5,000 or even 2,500 and require proportionately longer usage times.  Merely installing a full-spectrum/natural daylight bulb into your domestic light fittings will not make a blind bit of difference, as the light isn’t anywhere near strong enough.  Full-spectrum bright lightboxes were probably introduced because so many people find fluorescent light to be visually unpleasant, and there is a demand for a better colour temperature.  If you are going for a fluorescent lightbox, you may want to see if you can view a normal and a full-spectrum version to find out if you do prefer one or the other, but to be honest I think very few people are bothered about this, and that you’re better off using an LED lightbox if you don’t like fluorescent light.

Lightboxes are used for periods ranging from 15 min to 2 hours, depending on the type and the patient’s needs.  Unless you have Advanced Sleep Phase Syndrome, where you fall asleep too early in the day, the usual time of treatment is first thing in the morning, just after you get up (which for some people isn’t actually morning!), whether this is for sleep disorders or depression.  If you have DSPS or Non-24 Sleep-Wake Cycle, using bright light therapy in the morning has a high chance of stabilising your circadian clock and can even move it backwards so that you are falling asleep and waking up earlier.  I found that using a bright light box just after awakening immediately stabilised my sleep pattern at 24 hours instead of the 25 it had been on for years, and I started this four and a half years ago.  However, if my bedtime and waking time were too late, I needed to combine bright light therapy with a few days of sleeping tablets, taking the tablets an hour earlier each evening.  After that, the morning light therapy would serve to keep my waking time where it should be.  This has worked pretty well for me, although my sleep pattern wandered out of synch a few times a year and needed to be chased back.  Adding darkness therapy into the mix seems to have stabilised it completely.

There are two main types of lightbox, compact fluorescent and LED.  Fluorescent are the traditional ones and have been around for longer.  They are larger, require a longer treatment time, produce white light, and may cause medical problems for people sensitive to fluorescent light, such as migraine, visual problems, dizziness and so on.  The manufacturers try to dodge here and say that they have better ballast, but in my experience they’re just as bad as strip lighting and can cause nasty migraines. Perhaps they are better constructed, but since the light is so much brighter and it’s right by your face, it’s still more than enough to cause problems if you have difficulty with fluorescent light.  On the other hand, because they’re larger and the light is not as directional as LED light, they permit a little more freedom of movement when you are in front of them, though you still can’t move far away.  The light is also more likely to end up in the optimal position above your eyes, though since fluorescent lightboxes take much longer to use than LED lightboxes despite this, the advantage is probably cancelled out.  When looking at the stats for a fluorescent lightbox, most will say that they produce 10,000 lux, but you should also check at what distance that measurement is accurate.  If it’s 10,000 lux at 20 cm, that’s far too close to the light to be comfortable.  60 cm is more sensible, or alternatively just realise that you will need to use the lightbox for longer.  I think that this is how manufacturers are getting around the problem that everyone is told to look for 10,000 lux, but no one is quite sure what it really means and don’t realise that it’s only the measurement of the light intensity at a certain distance.

LED lightboxes have been around for a few years and may produce either white or blue light, which you can read more about here.  They are smaller and require a shorter treatment time.  Not everyone gets on with coloured light, and as the LED panel is composed of lots of little LEDs that look like dots, some people report getting spotting in front of their eyes, although I suspect that they were using the lightbox incorrectly.  You’re not meant to stare into it, you’re meant to position it at the side, or even better above your eyes, so that it hits your peripheral vision. LED lightboxes do have the disadvantage of needing to be placed more exactly and requiring you to stay in the same position, as the light produced by LEDs has a very narrow beam angle.  I use mine by my laptop or while sitting at my sewing desk, and while sometimes I need to prop up the lightbox to get it at the right angle, after that it’s fine.

I have a GoLite, previously made by Apollo and now made by Philips, which is a blue LED lightbox and very highly thought-of.  I also have a Lite-Pad, which is a cheap white LED lightbox I picked up on eBay for a tenner.  I use this one by my sewing table to save messing around with cables when I want to quilt during my morning lightbox stint, and also so that it doesn’t affect my colour judgement.  The GoLite does have a lot more bells and whistles, such as a clock and the ability to set both the light intensity and the length of time for up to three different preset programmes, but you’re paying a lot for them.  The Zadro looks like the best of the cheap lightboxes if you’re in the US, and indeed looks like a very good lightbox in its own right.  You can also buy combination lightbox/dawn simulators, of which more later.

There’s another type of bright light therapy around, known as the light visor, where the unit is placed in a sort of cap worn on the head, and the light is shone into the eyes from above.  Lumie makes a few, and there’s one which produces blue-green light around.  Their one advantage is that you don’t have to be tethered to your lightbox, you can move around.  Psycheducation.org is doubtful about them, and I agree.

Since you can’t tell which lightbox you will get on with in advance, or even if it will work for you, and since these things are very expensive, find a company who will offer either hire-purchase (e.g. the National Light Hire Company) or a free trial (e.g. Lumie).  You may need to spend a while working out the right amount of time to use the lightbox for.

Of course, an entirely free alternative is simply to make sure you get outside for at least one hour every morning.  It doesn’t matter if it’s cloudy.  I’ve run into a woman online who managed to get the same effect by using a 150w fluorescent light (that’s actually 150w, not the equivalent to 150w incandescent), such as this grow light, in her overhead light during the whole day, not just for an hour.  This is far, far brighter than normal domestic lighting, and while it won’t save you energy and many people (especially with ME) will find it uncomfortable on the eyes and/or likely to provoke migraine, for some people it’s a good solution.

Another possible solution is to buy an LED bulb in white or blue and sit with it at a level just above your eyes for a couple of hours a day.  The blue bulb will be exactly the right wavelength, and while the white won’t have as much blue, white LEDs peak at the right wavelength so it will have a lot of it.  It won’t be as strong as a therapeutic lightbox but if you use it for long enough and keep it close to the top of your eyes, you may be able to get a decent result out of it.  If anyone tries this, do let me know how you get on.  I’ve got one of the blue bulbs which I’ve used for experimenting with moonlight simulation (this is popularly known as Lunaception and is meant to improve menstrual cycles, although for me it just wrecked my sleep), and I’ve noticed that I tend to feel wired after looking at it, and that using it for half the day was enough stimulation that I had a great deal of trouble sleeping that night.  So I reckon there’s quite a bit of potential with those little blue bulbs, and they’re better filtered than lightboxes so you don’t get spotting even if you look straight at them.