Darkness therapy

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.

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15 Comments on “Darkness therapy”

  1. Grace Says:

    Thanks for the great posts. Your site is really wonderful, and I’m learning a lot from reading it.

    I’m thinking about trialling darkness therapy. I want to cover my mobile phone and mp3 player with some kind of colour filter – do you think that a yellow or orange cellophane would work as well as a lighting gel?


    • I don’t know, how thick is the cellophane? I’ve not got round to using it yet, but I bought a little blue LED key ring torch for the purpose of testing such things, and it cost all of £1.29 including P&P from eBay. You could get one of those, shine it through the cellophane, and if the blue light makes it through then you know that the cellophane is letting blue light through. Even so, mobile phones and MP3 players have small screens, I doubt it would matter much. It’s computers and TVs that are the main culprits.

      Glad you like the site!

  2. Robert Says:

    Will any yellow light bulb with a thick coat do? They sell some at the local Home Depot, but they sell them as bug lights – http://www.homedepot.com/h_d1/N-5yc1vZ1xqd/R-100672891/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

    Do those yellow fluorescent bulbs block out the blue light end of the spectrum? Or are incandescent bulbs superior for this purpose since most of them tend to produce yellowish light to begin with?


    • I can’t tolerate fluorescent light myself so I haven’t tried one, but I do know that LowBlueLights.com sells fluorescent bug lights, and Wikipedia has a spectrographic analysis of a yellow fluorescent light, which makes it look very suitable. The wavelength we want to avoid here is 470nm or thereabouts, and you can see that it doesn’t start to peak until quite a bit above that. So I’d guess that you’d be fine. Let me know what the light is like when you get it, particularly if it’s a pleasant colour? Either comment here or here, or if you want to be really nice to me, both! I have read some Amazon reviews of yellow fluorescent bug lights where people complained that the light was a horrible colour, but then some people don’t like coloured light full stop so it could just have been that. I like yellow-coated incandescents and my partner can’t stand them, for instance.

  3. Robert Says:

    Thanks for your help! Based on a few nights of using 3 yellow fluorescent bug lights in my bathroom, combined with wearing my orange glasses for a few hours before bedtime(even while brushing my teeth in the bathroom, but not for showering), I think I notice they aren’t as stimulating as the amber translucent bulbs I had in there before. I mistakenly thought these amber translucents filtered out blue light, but transclucent bulbs of orange, amber or yellow or just about any color are poor blue blockers based on my experience and research.

    I think the amber bulbs I replaced a few days ago may have been stimulating since even though I had on my orange glasses(before going into the bathroom), the 25 minutes or so I spent in the bathroom with those amber translucent lights may have been the reason I woke up in the middle of the night(2:30 AM) 2 nights in a row, even though I went to bed around 12:00 AM(before I got the glasses I usually went to bed around 4:00 AM and would fall asleep around 4:30 AM.). Prior to the amber lights I had in my bathroom I just used regular incandescent bulbs(I had these in the first few nights I tried the orange glasses and slept well without waking up in the middle of the night; I had my orange glasses on while brushing my teeth, but not for showering). I haven’t woke up in the middle of the night since I put in the yellow fluorescent bug lights.

    A few times over the past week I had to visit a sick relative at night. I took my orange glasses off for driving(and put them back on while I was at my relative’s place), and then drove home without them(feeling quite sleepy). I usually put my orange glasses on at 8 PM, but the 30 minutes I didn’t have my glasses on while driving back and forth(driving to my relative at 8:10 PM and returning home at 10:30 PM) and getting my eyes hit with light from other cars and various other sources, didn’t seem to affect my sleep quality at all surprisingly. As soon as I parked my car I put my glasses on, and went to bed at 12:00 AM which is pretty early for me.

    I’m also using a 10,000 lux light-box every morning at around 7:30 AM(I usually wake up around 7 AM, but have things to do first before I can sit at my computer with the light-box in front of me also). I think the light-box does stimulate me, and is also helping me wake up earlier, although I had been using the orange glasses for a few days before I got the light-box, and woke up early anyway.

    I suspect the blue-blocking coating used for both yellow incandescent and fluorescent lights may deteriorate over time, due to the light itself, heat, moisture, air, and temperature changes. So I suspect the light may allow more blue over time. I’m contemplating putting orange screens around these lights.

    I have very crudely “tested” both those amber translucent lights and the yellow fluorescent bug lights using the back of a CD: I see a complete color spectrum(including blue) reflecting off of the CD when I hold it under the amber lights, which shows that they do in fact contain blue(like all regular incandescent light bulbs), while the yellow bug lights show an incomplete spectrum of red, yellow and green. I guess that means the yellow coating is in fact filtering out the blue. I realize this is crude and probably not very accurate, but it may be a simple way to test lights to see if they contain blue light.

    I’ve also been exploring in my readings the connection between serotonin and melatonin. I’m not sure if more serotonin during the day = more melatonin at night. Eating fermented foods with a lot of friendly bacteria may be a good way to boost serotonin levels, and it seems serotonin does get converted to melatonin to some extent. So much of the body’s serotonin is created near or in the digestive system, and friendly bacteria may play a role in this.

    Anyway, so I no longer have to take sleeping pills to force myself to go to bed early and wake up early. Soon I will be 2 weeks into using the orange glasses. I don’t have to cut down on coffee though or caffeinated beverages since I never drank them to begin with.

    I don’t feel as refreshed when I wake up as I did the first few nights I used the orange glasses. Perhaps I was delighted by how I was able to get up so early and that made it even more refreshing. Now I’m getting used to waking up early. I’m looking for ways to always wake up feeling refreshed. Great blog you have, and thanks for sharing your ideas.


  4. Yes, I tried a translucent bulb briefly when I first started playing around with all of this, and quickly realised that it wouldn’t block blue light remotely well, which is why I always recommend bulbs with solid coatings.

    My sleep isn’t as good at the moment either, but it seems to be due to medication changes, and it’s still a lot better than it was before I started the darkness therapy.

    As for whether serotonin in the day affects melatonin at night, it’s probably hard to tell since a lot of studies are focusing on depression. If you improve depression by raising serotonin levels, chances are that the relief from the depression will improve sleep, without necessarily meaning that melatonin levels at night have gone up. I know that when I started using a lightbox in the morning but no darkness therapy, my 25 hour cycle immediately changed to a 24 hour cycle, but it still tended to be on the late side and I still had trouble getting to sleep. Adding in darkness therapy made a mammoth difference to my sleep onset and the quality of my sleep. I’d guess that in my case, the additional serotonin in the morning affected my overall circadian clock, but probably didn’t do much, if anything, for my melatonin levels at night. I’m curious as to what would have happened if I’d started off with darkness therapy alone.

    It seems that different people have different tolerance levels for small amounts of blue light creeping in, for instance around the edges of orange glasses. If you’re finding that even with the orange glasses it still makes a big difference, you could even try red light bulbs, as one sleep blogger is doing. I believe he starts with orange specs and yellow bulbs three hours before bed, then changes the yellow bulbs to red bulbs an hour before bed. At the moment my bulb set-up is that I have a couple of yellow bulbs in the hall to shine into the bathroom for showering, a pink 15W bulb in the salt lamp by the bed (still not sure whether any blue light gets through, but if so it won’t be much), and everything else is a standard incandescent or dimmable halogen, though I prefer keeping the lighting dim anyway. For the first five months when my sleep was fantastic, it didn’t seem to make a difference as long as the orange glasses were on. Now that my sleep’s not quite as good (current theory is that it’s the mega-doses of B vitamins my specialist has me on), I do notice a bit of a difference with the evenings when my partner’s out and I just use the salt lamp. I’m excited to hear about the CD test, and have just tried it myself. The yellow-coated bulbs don’t appear to show any blue, though a fair amount of green is showing. This is with the CD right by the bulbs, anyway, and I’m pretty far away from them when I’m in the shower. The pink bulb in the salt lamp was far more focused on red and yellow with a little green, and I was straining to see whether there was a tiny bit of blue or not. I think not, and to be honest, at that level I doubt it would do much harm. There are perhaps bulbs which would be even better in that lamp, but you do have to make a compromise regarding what you find visually comfortable, and it’s very dim anyway.

  5. Dani Says:

    Here is a site that explains how to make a DIY spectrometer with a CD:
    http://www.cs.cmu.edu/~zhuxj/astro/html/spectrometer.html

    I made one (although not as perfectly as I wanted) and I think it does a pretty decent job showing you which bulb or filter works or not.

    By the way – red leds are great for night-time use. No blue whatsoever, dim enough – I use 3 or 4 in each room.

  6. G Says:

    First of all, thank you for your well-written and very informative post. You mentioned using amber gel for your computer monitor. I looked into this and found they come in colours such as bastard amber, golden amber, deep amber,… etc. Which type of amber gel are you currently using? Thanks again for a great post!

  7. G Says:

    Just wanted to pass on this link for anyone that may be interested: http://www.stereopsis.com/flux/.

  8. lynn Says:

    I have bought yellow bulbs from LowBlueLights and yellow incandescent bug light bulbs in the past. They all differ in color output even among the dame brands. It does seem like the yellow coating may fade a bit over time like a previous commenter mentioned. Is there any way of testing the amount of blue light accurately?


    • I don’t know of any proper accurate method, but the one I do know of is to take a CD or DVD and angle it about a bit so that you can see the rainbow of colours reflecting off the back. If there’s any blue being reflected, then your bulb is letting blue light through

  9. A Says:

    Thanks for sharing all your info. It is helpful and interesting.

  10. Louis Says:

    Hi. I read on another website regarding the light blocking glasses which stated that there are a lot of ‘blue blocking’ products out there that use amber or orange coloured lenses, and while Amber lensing may be more practical in some cases for night vision, red coloured products will be much more effective for one reason. Research shows that green light also blocks melatonin production, perhaps as much as blue light. Amber and orange coloured lenses may block blue light but not block green spectrum light, while red coloured protection will block both green and blue.

    I was wondering what your thoughts on this are and whether you know if green light is just as harmful as blue light? Thanks.


    • I read a bit on it some years ago. I seem to recall that there’s a website selling green bright light boxes, which thus has an interest in telling everyone that green is the way to go. I’m not sure how that would work in terms of melatonin suppression. To be honest, I think the easiest thing to do is to try it out and see what you need. Different people will have different needs in this respect. I read a blog by one chap who sits in total darkness for hours before bed, which few people could cope with, and another by someone who starts off with yellow light in the evening and gradually ramps it down to red before bed. Coloured light bulbs are cheap, and if you install f.lux on your computer, you can use the “darkroom setting” that makes your screen red and black. Let us know how you get on!

      I ended up getting a new pair of orange specs made up the other month, and the old pair now lives at my partner’s flat. The tint on the old pair must have faded a bit, it’s noticeably less than with the new pair. I’m still trying to work out whether that affects my sleep.

      • Louis Says:

        Ok, thanks for that, I just bought a pair of blue light blocking glasses and will see how I get on with those. I was wondering whether you can recommend any where to buy the lightbulbs that block blue light? There are so many dodgy sites out there that sometimes I feel it best to go by personal recommendation. Thanks.


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