By now you may be feeling rather overwhelmed by all the colours I talk about for darkness therapy. Between my own visual comfort and what is actually available, I use products in a variety of colours. The one thing they all have in common is that they either block/filter out blue light, or they product light which does not have any blue in it. This means you can use yellow, orange, amber, red, or brown. You may find that you have strong preferences concerning colour to the point where the wrong one for you makes you feel unwell, particularly if you have dyslexia, migraine, ME/CFIDS, Meares-Irlen Syndrome, epilepsy, and possibly severe myopia (short-sightedness). Make sure you can try out a colour before committing to anything expensive.
Yellow
This is the lightest colour of the set. When used to tint glasses, it increases contrast in a way some people can find disconcerting. It’s often available as a standard tint for sunglasses, though be sure to ask your optician whether it blocks 100% of blue light. I have seen some websites selling yellow lenses that claimed that they would work for darkness therapy, but this study suggests that they may not.
I’ve seen two shades of yellow used as a coating for incandescent light bulbs. Most often it’s the slightly more orangey one. The light is a little more orange than you’d expect from looking at the bulb coating, and may be described as a marigold yellow. I personally find it very pleasant.
Reflector bulbs can be sold with a yellow coating, but unless you are going to be using tinted glasses as well, I don’t recommend these as the coating is only translucent and I think it permits some blue light to come through.
Fluorescent bulbs can be bought with a yellow coating as well. I don’t know what they’re like as I’ve never tried one. They’re often sold as “bug lights”.
Yellow is rarely used for LEDs, and on the two occasions when I bought something that was sold to me as containing yellow LEDs, they turned out to be a horrible orange. I’ve been told by lighting specialists that yellow is a tricky colour for LEDs, which is why you don’t see it often.
Candle flames are mostly yellow, although these is a small amount of white light in there as well which may or may not be enough to influence your circadian rhythm.
Orange
This is the colour I chose for my tinted glasses, mainly because it’s directly opposite blue on the colour wheel and I already knew that I got on with it from using an orange monitor filter on my laptop. Objects viewed through orange lenses appear golden yellow, for some reason. I find it quite a pleasant colour for lenses, it doesn’t increase contrast, and as apparently is true for many people, it makes it easier for me to read. The colour distortion may bother you, however.
Orange-coated incandescent lightbulbs are likely to be sold as “amber”, but the coating looks pinkish-orange to me. The light is a fair bit darker than that produced by yellow-coated incandescent bulbs, being an orange that is almost closer to pink.
Orange-coated reflector bulbs are also usually sold as “amber”. The coating is again translucent, but I think it probably cuts out most, if not all, blue light. It’s not the best light source, though, I wouldn’t recommend it.
Orange LEDs are commonly used for appliances, such as on electrical sockets. Again, there seems to be difficulty in getting a pleasant colour, although the light on my kettle is not bad.
If you wish to buy a salt lamp for decorative purposes, the thick layer of salt looks pink when it is not illuminated and glows orange when you put a bulb in it. I suspect that a small amount of white light is still getting through mine, so I put in a pink-coated 15W bulb instead and it nows glows a deep salmon colour.
Amber and brown
Amber may be used to refer to orange, or it may be a shade of brown (orange + black). Amber and brown are common colours for sunglasses, although it has been suggested that not all sunglasses which claim to block all blue light actually do so. I have no idea whether this is true, I suspect that it may be a marketing myth, but again, check with your optician.
The main advantage of brown is that it doesn’t distort colour in the way that orange does, and the disadvantage is that in order for it to be strong enough to block blue light, it will be quite a bit darker than the equivalent orange. I tried a pair of amber fitover blue-blocking glasses and not only did everything appear very dark through them, but they completely hid the parts of my face which were behind them. My orange glasses do nothing of the sort.
Red
Red is the darkest pure colour of the set, and anything viewed by red light or through a red filter will appear monochrome. This will be off-putting for many people. On the other hand, there’s a school of thought that red is far more effective than orange or yellow for darkness therapy, so you may prefer to use it for that reason. However, this site claims that “red is a very uncomfortable color to look through”, so you may prefer to restrict its use to light bulbs.
Red-coated incandescent bulbs exist, but I have not tried them. You can also buy incandescent bulbs with red (translucent) glass called “fireglow” which will give off more light than the solid-coated bulbs, but I don’t know if the translucent coating is enough to filter out blue light. Red reflector bulbs are probably similar to these.
Red LEDs are cheap to produce and give off a pleasant colour, so they’re commonly seen in remote controls and so forth. If you want to use a bike light as the equivalent of a torch, it will probably be red.
Red glass is a popular option for tealight holders. While the jury is still out on whether candlelight is acceptable for darkness therapy, I would guess that putting the candle into a red candle holder should be enough to compensate for the small amount of white light that may be present.