The idea behind this is that humans do best when they have melatonin being produced for half the time (averaged out over a year, it won’t be 12 hours all the time unless you’re living on the equator), and that it’s useful both for aiding sleep and for other things such as fertility and cancer risk. I’m a little warier of claims that a yellow light bulb will fight cancer/get you pregnant than I am of the claims that it will improve sleep, so I’d treat that side of things as rather more speculative, but there does seem to be a fair amount of research backing it all up, if indirectly. While darkness therapy itself may be fairly new, the various roles of melatonin have been studied a great deal by now. There have been studies using 12 hours of complete darkness to treat bipolar disorder, but this is difficult to implement and is generally thought not to be necessary, though I’ve read a website by one guy who feels that it is essential and discusses washing up in the dark! So while there appears to be a great deal of research on melatonin and sleep in general, for instance how shift work affects breast cancer risk, or on populations who do not have artificial lighting (and have many other major difference from industrialised countries), there is as yet little where researchers have directly studied darkness therapy by taking a group of people and changing nothing except the amount of darkness they get at night. Hopefully this will be remedied before too long, although since there’s nothing in it for pharmaceutical companies, it may take a while. All the research that I do know of can be found at LowBlueLights.com.
Since it’s blue light which affects circadian rhythms and tells the body that it should be awake and not producing melatonin, you can practise darkness therapy by simply omitting or filtering out blue light for several hours before you go to bed and while you are in bed. There are a few ways of doing this, but the crucial thing is that once you have begun the darkness therapy in the evening, you do not get any white or blue light until the next morning, not even the tiniest bit.
Coloured light bulbs. For general use while awake, I prefer yellow-coated incandescent bulbs. If you’re in the UK, they’re just sold as yellow bulbs. If you’re in the US, they’re more likely to be called bug lights. The bulb should be painted completely yellow, with a solid coating rather than a translucent one, and will produce an amber light which I find pleasant but which my partner, who generally dislikes coloured light, can’t stand. You can also get amber, red, or pink-coated bulbs, which you may prefer. I’m not entirely sure whether the pink ones will filter out all blue light when used in an ordinary lamp, as I’ve only ever tried a 15W one inside a salt lamp, where the thick salt already filters out most of the blue.
Unless you live alone or are only planning to use these lights while alone (e.g. while breastfeeding or if you need to get up in the night because you can’t sleep), this is a potential snag. As the coating is substantial, it will reduce the overall light output so that a 60W yellow bulb may be only as bright as a 40W white bulb, or even dimmer than that. You can buy fluorescent versions of these yellow-painted lights as well. I haven’t tried them yet as I respond so badly to all fluorescent light, but I’m curious about how the yellow coating changes the level of visual comfort by filtering out certain bandwidths. I tried buying an LED bulb that was sold to me as yellow, but it turned out to be a really nasty street-light orange; same goes for the two types of LED tea lights that I’ve tried. I’ve been told by several lighting merchants that oranges and yellows are problematic for LEDs, it’s hard to get a pleasant colour. I haven’t tried yellow halogen bulbs, but from the photos the yellow coating doesn’t look strong enough to block all blue light.
For use when I’m going to the toilet at night, I bought a couple of red bike lights. Since I’m an evening bather, showering was a problem. I originally tried a red bike light, but while I can cope relatively well in near-darkness, it just wasn’t safe. After puzzling over this for some time, I put a couple of lamps with 60W yellow bulbs on the hall, so that when the bathroom door is open, there’s a decent amount of light.
Even with coloured light bulbs, it’s best to keep the lighting in the evening fairly low. At one point I had a 60w yellow bulb in a desk light by the bed for reading by, and a 25w bulb hidden behind a vase in the corner on my partner’s side of the bed for ambient background lighting. Once I got the orange glasses, I eventually stopped using those, though I did acquire a salt lamp for ambient lighting which provides a nice orange glow. (As far as I can tell, the salt lamp filters out most blue light but not all, so you may need to get a coloured bulb for it if you’re going to be using it without tinted glasses on.) If you do get tinted glasses, I’d recommend keeping on one lamp with a yellow bulb by the bed, for the occasions when you need a bit of light during the night and don’t want to put your glasses on. There are various forms of gentle ambient lighting which are naturally low in blue light, such as candles or fairy lights, and for some people these will be an acceptable compromise. If you go for fairy lights and you’re not going to be using tinted glasses, go for rice lights, which are a warm white, instead of LED lights, which are a cold light containing a lot of blue. Unfortunately, I’ve found that even the small amount of light from fairy lights can be enough to halt melatonin production and keep me awake for hours if I don’t have my orange glasses on. I may try “golden” LED fairy lights some time, but since all of the LEDs I’ve bought as yellow turned out to be a nasty orange, at the moment I’m using the salt lamp for my one yellow lamp.
Monitor filters. Computers and television screens emit an awful lot of blue light, and using them in the evening can really mess up your sleep all on its own. Low Blue Lights and its friends sell expensive amber filters, but I simply got some samples of amber gels from a theatrical lighting company and cut them to size. They stick on fairly well by static, unless you have the computer screen tilted quite far forward, and are easy to take off for daytime use. I have a 17″ widescreen laptop and there are several inches to spare, so these would probably do you for up to 19″ or 20″ widescreen. They’re a bit of a nuisance, they won’t work for larger monitors, and again my partner doesn’t like looking at them (some people just don’t get on with coloured light), but they’re cheap. Brown filters should theoretically do the same job with minimal colour distortion if you can’t stand orange, though they will need to be fairly dark.
If you’re looking at a monitor through an amber filter or glasses, colours will be quite strongly affected. The general effect is golden yellow more than orange, oddly enough. Whites will be yellow, blues will be greens, everything will be a bit different. This may annoy you, and it may restrict your activities. I can’t do any quilting that requires me to select colours, and it’s not the time to go internet shopping for clothes. This isn’t entirely a bad thing, as it forces me to wind down in the evenings and look at those hours during darkness therapy as relaxation time.
Tinted glasses. There are two ways of doing this. You can buy ready-made tinted glasses which will block all blue light, for instance from the range at Optima Low Vision, or you can get prescription glasses made up with a tint that will block blue light. If you want to try standard sunglasses in brown, orange, yellow or red, check with an optician to find out whether they block 100% of blue light, as apparently most of them don’t. You also want these glasses to provide good coverage, as opposed to some of the tiny lenses you can get these days.
If you’re going for anything expensive, try out darkness therapy with coloured bulbs and optionally monitor filters first to see whether you get on with it and whether it helps. Since I can’t see without glasses, I decided to try some fitover glasses in amber which had the advantage of very good coverage.
Unfortunately I found them horribly uncomfortable, and they looked terrifying on me, being huge and so dark (much darker than the image shows) that my eyes were utterly obscured, along with half my face. My partner and I didn’t want our evenings together spoilt by this, so I gave up on the fitover school of thought and had some prescription glasses made up instead.
On my optometrist’s advice, they were tinted with Wratten Tint 21, which is a pleasant orange. Optical Express (who do some rather nice cheap frames) don’t do that tint as standard, but they could get that orange in 50% light transmission, which was more than enough to block 100% of blue light but still not so dark that my eyes were obscured to someone looking at me. They called it 500 Orange 50%, and it cost the same as an ordinary tint. (Remember that brown is just orange with black added, so while they will look more conventional and may distort colours less, brown-tinted glasses will need to be darker.) The glasses are rather fetching, if I say so myself, and I’ve had no complaints that they make me odd to be around.
I still keep the ambient lighting low when possible, as there will be a bit of light creeping in around the edges, and sometimes I put on the salt lamp so that the light is a soft orange. However, I’ve spent enough time wearing these glasses with ordinary indoor lighting to confirm that they work beautifully in any conditions, and you don’t need to worry too much about what your light bulbs are up to.
I generally put on the glasses at about 9.30 for a bedtime of midnight, and have been using them for four months. I’m getting sleepy earlier in the evening, sometimes I even fall asleep at 11ish, and I’m sleeping more solidly. I’d estimate the effect of the darkness therapy to be similar to that of taking a sleeping tablet in terms of getting a good night’s sleep, but without the potential side effects or grogginess the next day. I find the glasses very relaxing to wear. If my partner comes home late in the evening, in the past I’d be so thoroughly woken up that I couldn’t get back to sleep for hours. Now he’s lucky to get a coherent “hello darling” out of me, and I go straight back to sleep. I haven’t had an episode of not being able to sleep until unholy o’clock in the morning, or waking up at night and not being able to get back to sleep for well over an hour, since I started using the glasses. There have been a few nights where I’ve forced myself to stay up until 2, yawning all the time, but where in the past (using bright light therapy alone) I would have messed up my sleep cycle by doing that and would be unable to sleep before 2 (or worse) for the nights afterwards, now (using bright light therapy, dawn simulation and darkness therapy) my sleep pattern snaps right back into place. The only exception to this is the one night where I made the mistake of having the fairy lights on for half an hour around midnight when my orange glasses were off, as I’d hoped that they were yellowy and dim enough not to disrupt melatonin production. The ensuing insomnia made me realise just how dreadful my sleep was in the old days, and how enormously it’s improved since then.
In Search of Mornings 
