Kelvin value for night time?
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What would be a good Kelvin value for bulbs in the evening for no effect on melatonin?
Lowest I can find is 2000k - is there much difference between 2000k/2100k/2200k? -
@zikzak I really do not know, but (I've not tried these) there are 2300K bulbs by Hyperikon that seem to get great reviews. I'm not sure if they have any that have the standard base, I'll look, but for now, here are these:
Make sure that's the one with the gold base, I'm in darkroom mode and I'm not turning it off to check. It does NOT warm up the color when you dim, but hopefully it will dim quite well. Also look for regular (E26) base bulbs, there are small E12 chandeileir bulbs.
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Gold base? Do you mean brass?
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I just ordered a few of these - they are 2000k - I'll see how they are...
http://catalogus.electrocirkel.com/en/calex/search/goldline -
Oh I can't use those; they're all 240V and we have 120V power. They'd be super dim.
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@TwoCables I think 12v lighting (if you can get a source to run them) are much brighter than 120v lights. A 25 watt bulb can put off over 320 lumens!
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@Tungsten_smooth said:
@TwoCables I think 12v lighting (if you can get a source to run them) are much brighter than 120v lights. A 25 watt bulb can put off over 320 lumens!
I don't understand how this relates. The page that zikzak linked to shows 240V light bulbs. They would be very dim on 120V power (probably exactly half their maximum brightness). That's my point.
So, why are you talking about 12V lighting being brighter than 120V lights?
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@TwoCables just discussing different voltages.
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I bought one of these and a few more Calex bulbs - very satisfied... 2000k Ra 99
https://res.cloudinary.com/greenline/image/upload/c_limit,q_90,w_1280/v1428398771/calex-goldline-xxl-o180-3171.jpg
It's huge - do a google search for size :) -
@zikzak The Kelvin value alone isn't what determines the effect on melatonin. It depends entirely on the absolute brightness of the blue-green component of the light hitting your eyes. Colour temperature in Kelvin is basically a measure of the relative mixture of red, green, and blue components, but your body only pays attention to the blue-green. A 25-watt 2700K bulb might have less effect on melatonin than a 60-watt 2000K bulb. You'd have to measure it, for example with a light meter covered with a blue-green filter. It also depends on how far away you're sitting from it, the reflectivity of objects around you, and so on.
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@Elhem-Enohpi cyan and green are also very stimulating, but after maybe an hour according to harvard research:
http://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side, blue light starts to affect (delay) sleep more strongly. -
@Tungsten_smooth Ok, I changed it to say blue-green instead of blue.
The point is that the Kelvin value is more of a measure of the relative proportions of red, green, and blue in a light source, and in terms of melatonin, your body doesn't care about that. It's sensitive to the brightness and length of time you're exposed to light with a wavelength of around 500 nm (cyan), dropping off as it goes higher or lower than that. The presence or absence of other wavelengths, which is what determines the colour temperature in Kelvin, is more or less irrelevant.
It's possible for one bulb with a colour temperature of 2000K, and another with 7000K, to have exactly the same effect on melatonin, if they're of different wattages and distances.
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@Elhem-Enohpi Thanks a lot! That cleared things up a bit for me.. So how can determine what bulbs to buy?
For instance, I have some Philips Hue bulbs and at night I set them to 2000k and relative low brightness. I always thought I was "safe" in terms of the effect on melatonin but I guess I would have to know their exact combination of wavelengths? -
@zikzak If you want to be sure that it's "safe" and has no effect on melatonin, set your Hue light to pure red. Otherwise, it's a bit of a guessing game. Even a 2000K light has a certain amount of blue-green or melanopic light in it - about 6% compared to white light, according to f.lux. Whether that has any effect depends a lot on how close you are to it. If you use two bulbs, it doubles your exposure. An Apple 27" screen at 1200K is still too much blue-green light if you sit 12" away, according to f.luxometer, and you need to dim the backlight.
I suppose there is a certain colour temperature that has virtually no melanopic light, but I think it would be less than 1000K, and look deep orange or red.
At night I use a single cheap 4-watt 2700K LED bulb. I put an orange filter over it, which blocks 90% or more of melanopic light, and I put it behind a barrier so it's all indirect light bounced off the wall. Seems to work for me.
The exact combination of wavelengths doesn't matter. Your body's clock is only affected by the blue-green melanopic wavelengths. The other wavelengths aren't really significant either way.
What's important is:
- The absolute strength or power of the blue-green wavelengths.
- How far away from the light source you are.
- How long you're exposed.
- At what point in your circadian cycle the exposure takes place.
Computer screens are fairly standardized in brightness, and people generally sit the same distance away from them. From that you can get 1 and 2, and you can assume several hours of exposure, late at night, for 3 and 4. Knowing those factors, it's possible to calculate how much f.lux has to dim the blue-green wavelengths of your screen, to get it into a "safe" range of melanopic light, while still not making the screen pure red. The actual colour temperature that turns out to be, is a result of the calculations. For sitting in front of a standard computer screen, it comes to around 2000K.
Light bulbs are a completely different story. A bulb could be 10 watts or 100 watts. It could be half a metre in front of your face, or five metres behind your back. In terms of the amount of light that hits your eyes, that can mean a difference of several thousand times. So knowing the colour temperature is useless. It doesn't tell you any of the four factors - unless it's so low that the first factor is effectively zero. What you need to know is the melanopic lux, which is a measure of how much blue-green light is arriving at your retinas.
The only way to really know is to measure the strength of the melanopic wavelengths with a light meter, from your seating position. Most people don't have access to the $15,000 spectrometer that was used to make the f.luxometer simulator, so thankfully you can consult it online to get some ideas. For example, the Philips Hue at 2700K, 30 inches away, and dimmed to 12%, has a melanopic lux of 51.58. That's "good for the office, but too bright after dark", and can cause up to an hour in sleep phase shift if used late at night. On the other hand, setting it to 2000K and/or putting it behind you, may be fine. F.luxometer doesn't let you put those parameters in though, so it's difficult to say without actually measuring it.
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@Elhem-Enohpi I would say a light that puts out less than 200 lumens, incandescent only, because LED is not standardized at this stage, and used in a lamp on one side of a room should be fine. I've got a couple that do about 120 lumens!
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@Tungsten_smooth Interesting, what do you base the 200 lumens figure on? So 400 lumens would be too much?
I have another light I use at night once in a while, its colour temperature is 4000K. I calculated that it puts out about 120 quadrillion lumens. It doesn't seem to bother me. I sit pretty far away from it.
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@Elhem-Enohpi Thanks a lot for the elaborate answer! You kinda said it already - but this post was so detailed that I got a much better understanding of it. I still feel it's hard to actually know how much the effect is for different scenarios.. I'm not the type of person that feels a big difference from light. I'm very sensitive to light but can't really feel the difference in regards to sleep. I'm trying to be on the safe side though as I have sleep problems in the second half of the night.
I don't know if you can set Philips Hue to pure red? - it seems some white goes along no matter what color..
The bulbs they have at lowbluelights.com would also be a good solution I guess:
https://www.lowbluelights.com/products.asp?cid=43 -
@zikzak You're welcome! Writing about it also helps me to clarify my own understanding - I still have a lot to learn.
Yes, it can be difficult to know what level of melanopic lux you're being exposed to from lighting. My approach has been to put a red-orange filter over the light, basically the same as wearing blue-blocking glasses, without the glasses. But that might be too extreme for some people. Don't know what my neighbours think!
I also have trouble sleeping through the night. Lighting helps somewhat, but I have to do a lot of other things, like trying to eat at regular times, not working too late, not drinking alcohol at night, and not staying up writing long posts on the Internet!
I've never used a Philips Hue, but in the f.luxometer there's a setting that says "redLED", which appears to be safe at any distance or brightness. Again, it's a bit extreme. I wouldn't like to use a monochromatic red LED light.
I'm not impressed with LowBlueLights. There's a lot of hype about "the latest in LowBlue LED technology", but they're just repackaging made-in-China monochromatic amber bulbs. They're mainly used in areas where outdoor lighting can endanger sea turtle hatchlings. The light quality is awful, the same as low-pressure sodium streetlamps. Not suitable for indoor lighting. The incandescent and fluorescent bulbs have a yellow-orange coating on them, which is fine I guess, but they seem overpriced. I doubt they actually design any of their own products. Plus their Facebook rant against f.lux is complete bull. I wouldn't give them my money.
Personally I don't see the need to spend $50-$100 on a "high-tech" light bulb, when you can get the same or better effect using a $5 bulb with an orange sock over it. To each his own though.
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Haha, yes the last things you mention of things to avoid is probably the hardest and most effectful..
I originally got Hue because of the possibility to change kelvin signature - I didn't think that I would use the colors. But now I actually use the red quite a lot - before bed, watching movies or sexy time - all very good with the red light. My girlfriend that thought it was a bit weird/cheesy at first now likes it too..
Good to hear you impression of LowBlueLights. Didn't know they had anything going against f.lux.. And I have had that thought also - that I didn't know what to make of their products in terms of quality and overprice..
I will try to do the same approach as you mention with a filter. I have some 2700k Ikea spots in my hallway that I would like to soften up a bit.
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@zikzak I'm using a Rosco Supergel #23 Orange. There might be something better, maybe the #22 or #25, but that's what they had in the shop near me. They give spectrum charts for every filter, on the website. It's quite easy to find, a good photography shop should have it. I paid about $10 for a large roll because I wanted to try putting it over my screen, but that didn't work out so well. Anyway, now I have a lifetime supply. I like the colour, it gives a sort of campfire effect, and I can still make out the colours of things in my room.
