Which is the best light troughout the day to stay in front of PC?
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Dr. Mercola likes to over-dramatize things so that he can sell his products. It's pretty much Scare Tactics 101 with him. It's not that he's necessarily wrong about things, but he goes too far and makes his readers think that they have a bunch of health problems to deal with even though they felt just fine before reading his articles. Even when he's not trying to sell one or more of his products, it's like he's one of those tin foil hat people. Y'know what I mean?
I don't know who this Dr. Jack Kruse is, but I would bet he kinda does the same thing.
I don't have any problems with leaving f.lux set to 6500K all day, and I literally LIVE at my computer (I spend all day at my computer, every single day). All you have to do is make sure your indoor lighting in your computer room is blended fairly well with the brightness of your monitor and vice versa. Oh, and of course, don't sit too close - like, you know, keep a distance between your monitor and your eyes of like say 2-3 feet or more.
I don't know if you can see how paranoid these 2 "doctors' are making you be, but it seems to me they have taken away your ability to just relax and enjoy your computer and your life. Try to stop listening to them so much. You're not going to hurt your eyes by simply using a computer. I mean really, look at the rest of the world. Or, look at me. I've been living at my computer for YEARS but I don't have any problems.
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You know, there is a lot of basic physics missing from these discussions. A lot of the claims are off by a factor of 1000 or more. So I think you should ask, first, how BRIGHT a light needs to be to do damage.
Retinal hazards happen because of a dose of energy that's too high, not only because of a particular wavelength.
First, yes, people do get really upset that the "blue" in a white LED is nearly all at the same wavelength, so when you use a spectrometer it LOOKS like a spike that might poke out your eye. But this is just your imagination - it doesn't actually work like that.
What actually matters is how much energy is absorbed by the retina, and we can measure energy in "joules" (which is watts times seconds - notice that duration matters!). And we also know that computer displays are just way too dim (hundreds of times dimmer) than light you see outdoors.
So in hazardous blue light terms: walking to your car (spending a minute outside) gives you a larger dose of blue light than 12 hours of looking at a computer screen.
But that's for an all-white screen. The same trouble (just more extreme) happens when people try to measure the spectrum of a black pixel. Again, it's 1000 times dimmer than a white screen, and your retina isn't going to notice this. At all.
Screens with better contrast look better, and colors that match their surroundings also look a lot better. There is a lot of complexity to glare, but more of it is about intensity than it is spectrum for common white lights.
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Dr. Wunsch may deserve his own section. He has claimed that IR light has a restorative effect on the retina (and so he claims, this is what makes indoor LEDs bad, because they don't emit IR). I recall he also worries about flicker, which is documented to cause headaches with fluorescent lighting, so this really is a thing to fix.
But the studies that show any effects like this (on rodents, which are dramatically more sensitive) are done at illuminance levels >100x brighter than indoor lighting.
Another theme you'll find in the retinal hazard literature is that the most pronounced effects are on albino rodents, which (to oversimplify) will lose their eyesight if they are placed in bright office lighting for a couple days. They are enormously sensitive to light (and nocturnal), and the results do not generalize to humans.
But again, I will say, before you can talk about spectrum, you MUST make the power similar. Our eyes are so good at hiding the effects of brightness from us - we go from outdoors to indoors (1000:1 in brightness sometimes) and don't really notice the difference. So this makes it very easy to talk about colors and spectra.
For actual retinal harm, again, you must think about dose (power * time) as the first concern, and spectrum as the second.
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To answer the overall topic:
Because I think "strong" circadian rhythms are very important to health, I think that we should work in places with more light, with brighter screens than we have today. And also, we should spend time before bed in much dimmer spaces.
Remember that a blue sky can be 50,000K. Outdoors, 5500K is the warm sunlight light you see.
With a lot of these topics, what we're colliding with is that the way we deliver artificial light (usually in small boxes attached to our ceilings) is not the right shape for the light, so just turning that light up doesn't always work or feel good. It creates new huge glare sources and feels uncomfortable. You don't go outside when the sky is blue and say "this has glare" even though that light is 50x brighter than what you just saw indoors.
We need to build better ways to bring natural light indoors. I think this should be through a combination of better daylighting, and also with better indoor fixtures.
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@herf yes I agree that we need to have more natural light indoors but what with this theory... https://www.facebook.com/drjackkruse/photos/a.568822376515454.1073741825.239883926075969/1771833539547659/?type=3&comment_id=1771884786209201&reply_comment_id=1774244012639945&force_theater=true¬if_t=photo_reply¬if_id=1495286220701254
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There are a few false/misunderstood ideas here:
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"Blue light causes myopia" No, it's quite the opposite, and we know that LACK of exposure to bright light during childhood is linked to myopia.
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"ICNIRP...": yes, it specifies a hazard spectrum, and also specifies a power + dose that affects the eye. Basically if you are seeing a >10,000 cd/m2 surface for long enough, there may be some calculated retinal hazard by ICNIRP. But your computer display is only 200 cd/m2. Surfaces outdoors are frequently 2000-5000 cd/m2.
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Humans have not been shown to experience Class 1 retinal harm ("Noell"): these experiments were done in albino rodents, and involve a rod system that continually sheds under moderate intensity light, which our rods do not seem to do.
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The wavelengths that affect circadian rhythms are different (more green) than those that are implicated in blue light hazard spectra (more high energy blue).
To demonstrate how the math looks here: in animal models, there is Class II harm (blue light hazard) in doses around 10 J/cm^2. So that is the number you want to exceed based on these standards. (Some of them allow a large safety margin, down to 2.2 J/cm^2).
The brightest screen we have measured (Apple’s 27" Thunderbolt Display viewed from about 20" away) makes 0.0000125 W/cm2 of “blue light hazard” irradiance. To get from Watts to Joules, you just multiply by seconds, and that gives a number we can compare to the retinal hazard experiments:
A 1-hour exposure to the very brightest screen we’ve measured is 0.045 J/cm2 at the cornea, a couple orders of magnitude below the threshold for damage.
And a 12 hour exposure? Only 0.54 J/cm2. So these are really different categories of dose.
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Here is a link to the myopia research - this is now in the ophthalmology textbooks, so it's very well regarded research:
http://www.cnn.com/2011/HEALTH/06/01/myopia.causes/
Regarding focal comfort, people with presbyopia (those older than 45) will find it easier to focus at close distances with bluer colors - adjusting to a warmer color will make these people need to push the screen another inch or two away.
It is true that blue light focuses closer, but for most people, it's a difference in intensity with the surroundings that causes eyestrain, not the focal accommodation.
Again, the blue sky is very very blue, and we shouldn't be afraid of it.
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You have me thinking differently about my lighting setup TwoCables and herf thanks for sharing, that was informative, even if I don't have a firm grasp of the physics behind it all.
Do you have any suggestions for people like myself who do not own a spectrophotometer or other technical equipment to loosely gauge whether intensity and contrast between the monitor and indoor lighting are appropriate?
Say I did buy a spectrometer or something, what then?
Herf, is that to say we need larger light fixtures?
I am fantasizing a DIY diffuse lighting system that covers the entire ceiling of a home with a material like soft light setups that photographers use.
I wonder if rolls could be ordered made of that material.
More importantly, I have yet to encounter a smart-bulb worth investing in mass quantities to make an array like I am imagining much less screw into the conventional wall/lamp sockets.
Have you come across any bulbs that you're excited about?
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@adamlogan said in Which is the best light troughout the day to stay in front of PC?:
You have me thinking differently about my lighting setup TwoCables and herf thanks for sharing, that was informative, even if I don't have a firm grasp of the physics behind it all.
Do you have any suggestions for people like myself who do not own a spectrophotometer or other technical equipment to loosely gauge whether intensity and contrast between the monitor and indoor lighting are appropriate?
Say I did buy a spectrometer or something, what then?
My suggestion is, don't worry about it because it doesn't really matter. There's no such thing as really having an "appropriate" balance like that. You don't need to use equipment like that (no one else here is doing that, at least that I'm aware of - because it's not needed). Besides, a computer monitor is nowhere near bright enough to matter or worry about in this regard. As long as you're comfortable and you're working on avoiding blue and bright light in the last ~3 hours of your day before you finally get into bed, you're fine. You don't have to get super technical with making sure everything is "perfect" somehow. There aren't any real rules to this. Y'know?
So, don't worry about it or think about it so much. Try to have a more casual and relaxed approach to all this stuff. F.lux exists to simply enable us to use our computers during the last ~3 hours of our day without being blasted by too much blue light. Of course, even then, you have to consider indoor lighting and the T.V. and other things that still emit too much blue light. Brightness is very important as well though: the brighter a light is, the more "alerting" it is. It's even worse when that light has a decent amount of blue light in it because the brighter a light is, the more intense all of its colors are (which I guess is obvious, but it's always worth mentioning).
Really though, I would say that we're over-thinking this a little bit too much. I think it can be just as simple as making sure you're doing your best to avoid blue light during the last ~3 hours of your day so that your body can begin producing melatonin and never be interrupted. So avoid very bright light too. You don't have to go any further or deeper than that. Think back to nature, back to basics, etc.
@adamlogan said in Which is the best light troughout the day to stay in front of PC?:
Herf, is that to say we need larger light fixtures?
I am fantasizing a DIY diffuse lighting system that covers the entire ceiling of a home with a material like soft light setups that photographers use.
I wonder if rolls could be ordered made of that material.
More importantly, I have yet to encounter a smart-bulb worth investing in mass quantities to make an array like I am imagining much less screw into the conventional wall/lamp sockets.
Have you come across any bulbs that you're excited about?
I know this wasn't directed at me, but I just have a comment to make: I'm really not so sure it's worth anyone's time or effort to take things this far.
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One way is to buy a cheap lux meter on Amazon, and post the values here for your workspace (with screen off and on), and the room you are in before bed (screen off and on).
These numbers ignore spectrum, but they make a neat discussion.
Here, we've lit our office at >500 lux of 5000K LED, and our house can do <5 lux of 1500K before bed. This nighttime setting is maybe extreme for some people, but I think it's actually a reasonable start to the "control" we need to affect circadian timing.
