Does LED lighting count as a dodgy technology?

[Buriedcode]

So, wait, you're saying your eyes started having problems since LED lighting was introduced in.. monitors? Or as general lighting?  How do you know this isn't co-incidental, related to age, or perhaps you need a new prescription for your glasses? Or of course, the fact almost everything is brighter these days? As several have mentioned in this thread, when trying to work out something as subjective as eye discomfort, it is important to to no jump to conclusions such as "it must be PWM" without confirming that the source of the discomfort is actually using PWM.  Or claiming that there's significant UV emitted, without testing the source?

You seem to have bundled together the "Strong emission of blue light" which is likely no more than CCFL sources, and relatively low frequency PWM dimming.  Again, no-one is disputing that strong blue light, or low frequency PWM dimming can't negatively affect the eye, but you're assuming that these two things are related and common, without anything to back it up.

I think almost everyone in this thread has seem the "flicker" or low frequency PWM's LED's, especially when turning ones gaze quickly, or in the case of car brake lights (which must be at 200Hz or something stupid).  But I haven't seen this is display backlights.  I'm sure they must use PWM, but I'll have to measure the frequency.

Sorry to keep banging on with the same themes, but you seem to have skipped over what others have said and just re-stated that you think its all "blue light and PWM". Also..

Any way, whether anyone here agrees with it or not, some people (aye!) have been permanently affected by LED backlighting, for whatever reasons.  And once that happens, our eyes become more sensitive to LED lighting in general.   

Who?  And how does it make the eye more sensitive to LED lighting? 

[Mr. Scram]

Lumping together blue light and flicker even after you're told they're two very different things screams having heard a thing that one time and attaching all kinds of far reaching conclusions to it. Move along, nothing to see here except proof that the scientific method is key to end up with something other than cargo cult nonsense.

[Kjelt]

This kindof things always occur with the introduction of new tech.
I remember a discussion twenty years ago about the electronic fluorescent energy saving bulbs.
There were people that really accused the bulb manufacturers of including mind psyche influencing electronics into the bulb that manipulated the people so they would be more compliant to government 

[Electro Detective]

Those electronic fluorescent energy saving bulbs were and still are sub standard lighting, hard on the eyes, tiring to work under, 

did the manufacturers evaluate a few in their mansions first, before shipping the eyesoreware out to retailers to flog to the connedsumers? 

They are apparently not land fill friendly either, which means they will appear in animal/peoples food and drink sometime in the future   

The latest LEDs are miles better in all respects, especially if you can no longer afford the superior halogen lighting bills   

[james_s]

I replaced almost all of my incandescent lamps with CFL in the late 90s and they seemed fine to me. LED is certainly superior though even just for the instant on and not minding short cycles.

[coppice]

Those electronic fluorescent energy saving bulbs were and still are sub standard lighting, hard on the eyes, tiring to work under, 

Electronic fluorescent energy saving bulbs are not just one thing. There are ones with bizarre colour rendering, and ones with very good colour rendering. There are ones that pulse at 100Hz/120Hz. and ones that operate from DC, with electronic handling of the negative resistance.

[Electro Detective]

All the ones I've come across over the years are poor quality light, be they blue-ish or yellow-ish  light,
high or low output = bad news for the eyes and attention span all round 

Sit and work under those for a few hours,

and then compare with LEDs or halogen the next day, for twice as long a period, and you'll ditch all the electronic fluorescent energy saving bulbs in a heartbeat.

I haven't done the bench homework yet for power draw, but strongly suspect LEDs are not too far off the 'energy saving' deal of fluorescents

[Kjelt]

LEDs are nowadays more energy efficient than fluorescent.

The bad rap comes from cheap drivers (in both cases). For professional lighting a driver contains many components, BOM over $12 a piece, that is good led driver.
The rest is asking for compromises, low lifetime, flicker due to PWM <1MHz with dimming or PWM <500Hz without dimming, etc. etc.
When the world changed from incandescent to LED the thing to aim for was a change of fixtures, so fixtures that had leds integrated but also a good qualiy driver.
However as it turns out consumers want the cheapest solutions, the fixtures and even the old fashioned E27 lampholder they were accustomed to over the years.
The whole consumption society changed from good quality to cheap replace within 4 years, so yeah you get what you pay for.

[scatterandfocus]

So, wait, you're saying your eyes started having problems since LED lighting was introduced in.. monitors? Or as general lighting?  How do you know this isn't co-incidental, related to age, or perhaps you need a new prescription for your glasses? Or of course, the fact almost everything is brighter these days? As several have mentioned in this thread, when trying to work out something as subjective as eye discomfort, it is important to to no jump to conclusions such as "it must be PWM" without confirming that the source of the discomfort is actually using PWM.  Or claiming that there's significant UV emitted, without testing the source?

You seem to have bundled together the "Strong emission of blue light" which is likely no more than CCFL sources, and relatively low frequency PWM dimming.  Again, no-one is disputing that strong blue light, or low frequency PWM dimming can't negatively affect the eye, but you're assuming that these two things are related and common, without anything to back it up.

I think almost everyone in this thread has seem the "flicker" or low frequency PWM's LED's, especially when turning ones gaze quickly, or in the case of car brake lights (which must be at 200Hz or something stupid).  But I haven't seen this is display backlights.  I'm sure they must use PWM, but I'll have to measure the frequency.

Sorry to keep banging on with the same themes, but you seem to have skipped over what others have said and just re-stated that you think its all "blue light and PWM". Also..

Any way, whether anyone here agrees with it or not, some people (aye!) have been permanently affected by LED backlighting, for whatever reasons.  And once that happens, our eyes become more sensitive to LED lighting in general.   

Who?  And how does it make the eye more sensitive to LED lighting?

Lumping together blue light and flicker even after you're told they're two very different things screams having heard a thing that one time and attaching all kinds of far reaching conclusions to it. Move along, nothing to see here except proof that the scientific method is key to end up with something other than cargo cult nonsense.

For computer displays, I have tinkered around with PWM frequencies and blue light reduction through software.  I'm not lumping them together.  It is being assumed that I am lumping them together to carry an argument.  Arguments based on assumptions don't make for constructive discussion.  Rather, they make for guaranteed back and forth bickering.  Where something isn't clear, it is always better to ask questions rather than to cast arguments based on personal assumptions.  Let's keep it civil and constructive.

What I have found in my admittedly limited tinkering is that for altering PWM frequencies using software (which definitely has major limitations), there isn't any major difference to my eyes once the PWM frequency is high enough not to see visible flickering (PWM lines).  With visible flickering, a display is terrible on my eyes, but upping the frequency to get out of that range isn't that much more comfortable, dependent on individual displays.  I suspect here that altering PWM brightness through software is much too limited in the frequency range.  And the issue is probably as much to do with the shape of the dimming waveform as the frequency, or at least it is likely a factor.  There are also the issues of polarization and diffusion.  And on altering overall color balance, I have found that moving toward a warmer overall color (more yellow) can be very helpful, but it also depends on what else the individual display is doing overall.  It is very touchy stuff dialing in a display for long term use, to my eyes.  And some displays are just unusable no matter what.  At this point, not knowing alot about what is going on in displays electronically and optically, I am very interested in finding out more.  And it is one of my motivations in learning electronics.  This year I bought some displays of different types (IPS, TN, VA) and experimented with them to find out what I could (within my technical limitations) and compared them to other displays that I already have.  One other issue that came up during that was the sharpness of text on a display, in addition to the PWM, blue light, and other issues mentioned above.  Going to measures for sharpening text, such as turning off anti-aliasing, can be very helpful.  And higher resolution (4K) can be very helpful.  But all of the issues are part of a bigger picture, where addressing any one of them alone is not a magic bullet for eye fatigue.

[scatterandfocus]

Those electronic fluorescent energy saving bulbs were and still are sub standard lighting, hard on the eyes, tiring to work under, 

did the manufacturers evaluate a few in their mansions first, before shipping the eyesoreware out to retailers to flog to the connedsumers? 

They are apparently not land fill friendly either, which means they will appear in animal/peoples food and drink sometime in the future   

The latest LEDs are miles better in all respects, especially if you can no longer afford the superior halogen lighting bills   

It seems to me that if some technology is physically uncomfortable, it would be good to know why it is the case.  The general mindset around lighting and displays today seems to buy to just buy more until we find something that is least uncomfortable, neverminding finding out something about why.  It would be a very good thing have some electronics knowledgeable people hacking on lighting and displays, toward the goal of better eye comfort.

[scatterandfocus]

Those electronic fluorescent energy saving bulbs were and still are sub standard lighting, hard on the eyes, tiring to work under, 

Electronic fluorescent energy saving bulbs are not just one thing. There are ones with bizarre colour rendering, and ones with very good colour rendering. There are ones that pulse at 100Hz/120Hz. and ones that operate from DC, with electronic handling of the negative resistance.

LEDs are nowadays more energy efficient than fluorescent.

The bad rap comes from cheap drivers (in both cases). For professional lighting a driver contains many components, BOM over $12 a piece, that is good led driver.
The rest is asking for compromises, low lifetime, flicker due to PWM <1MHz with dimming or PWM <500Hz without dimming, etc. etc.
When the world changed from incandescent to LED the thing to aim for was a change of fixtures, so fixtures that had leds integrated but also a good qualiy driver.
However as it turns out consumers want the cheapest solutions, the fixtures and even the old fashioned E27 lampholder they were accustomed to over the years.
The whole consumption society changed from good quality to cheap replace within 4 years, so yeah you get what you pay for.

How does a person buying lighting products today make a distinction between these aspects of fluorescent and LED lighting?  What should a person be looking for specifically?

[Kjelt]

Best you can do is buy the quality dimmable drivers yourself ($30-$75 each)
To be honest buying led bulbs you buy the low cost stuff where everything was cost down.

[scatterandfocus]

Best you can do is buy the quality dimmable drivers yourself ($30-$75 each)
To be honest buying led bulbs you buy the low cost stuff where everything was cost down.

Any recommendations for a DC supply and dimmer?

[scatterandfocus]

I also wonder what might be any complications in adding DC power and dimming to a computer monitor.

[Mr. Scram]

"Arguments based on assumptions don't make for constructive discussion."

Glad you're finally coming to that realisation. Time to shutter the thread?

[Gyro]

For computer displays, I have tinkered around with PWM frequencies and blue light reduction through software.  I'm not lumping them together.  It is being assumed that I am lumping them together to carry an argument.  Arguments based on assumptions don't make for constructive discussion.  Rather, they make for guaranteed back and forth bickering.  Where something isn't clear, it is always better to ask questions rather than to cast arguments based on personal assumptions.  Let's keep it civil and constructive.

Wait, you can't alter the LED PWM frequency in software, that's a hardware function of the LED driver chip. You can alter the LCD refresh rate in s/w but not the backlight PWM frequency.

Altering the backlight brightness will change the LED PWM duty cycle but not the frequency.

Blue light reduction, likewise, is a change to the colour palette and/or contrast of the LCD, not the backlight colour.

[james_s]

Seems like I read that there are some laptops that do allow the PWM frequency to be configured in software but I don't recall the details. In my case it was some new desktop monitors they got at a former job that had terrible PWM flicker. The laptops I have now both at home and at work are LED backlit and don't bother me a bit so YMMV.

[scatterandfocus]

For computer displays, I have tinkered around with PWM frequencies and blue light reduction through software.  I'm not lumping them together.  It is being assumed that I am lumping them together to carry an argument.  Arguments based on assumptions don't make for constructive discussion.  Rather, they make for guaranteed back and forth bickering.  Where something isn't clear, it is always better to ask questions rather than to cast arguments based on personal assumptions.  Let's keep it civil and constructive.

Wait, you can't alter the LED PWM frequency in software, that's a hardware function of the LED driver chip. You can alter the LCD refresh rate in s/w but not the backlight PWM frequency.

Altering the backlight brightness will change the LED PWM duty cycle but not the frequency.

Blue light reduction, likewise, is a change to the colour palette and/or contrast of the LCD, not the backlight colour.

I don't know if you are a Linux user or not, but there are commandline tools for adjusting PWM on Linux.  Maybe there is something out there for Windows and Mac OS too.  See for example:  https://aur.archlinux.org/packages/intelpwm-udev

The backlight has to go through the panel, so adjusting color of the display definitely does have an effect.  You can see this most noticeably by displaying a white page and adjusting colors, but it is very obvious even on a black page.  The backlight will always bleed through to some degree, even with VA panels which have considerably higher contrast ratio than IPS and TN panels.  Anyway, most displays that I have seen are way too blue by default.  I see blue screens everywhere I go.  Computers, tv's, information screens, cash register displays, and on and on.  Once you see it you can't unsee it.

I remember well over a decade now, blue LED indicators were trending in audio gear.  Many users complained of the harsh and glaring light, and manufacturers stopped using them.  They looked aesthetically nice initially, but they weren't so nice to the eyes.  A very common thing for gear using blue LED's was to cover them with black electrical tape.  Oddly, a single blue LED on a piece of audio gear was unacceptable to many buyers of audio gear.  But still today, blue LED's are used as the main backlighting for most displays, even though many users have eye discomfort from them.  Having a loud high frequency peak in audio wouldn't be acceptable by anyone for audio gear.  It would be deemed as uncomfortable to listen to.  But we have the optical equivalent in LED lighting with a strong blue band dominating the light output, especially with computer displays.  That is why manufacturers have turned to more yellow and dimmer LED lights.  And I agree with anyone who says that the yellow'ish LED lights aren't so great.  But it seems to be one way or the other so far with LED lighting.  If this were audio we are talking about, the yellowing would be the equivalent of rolling off the highest frequencies so that we are only hearing the midrange.  It wouldn't be as uncomfortable to listen to as with a strong high frequency peak, but it also isn't good quality audio, the same as heavily yellowed blue LED's isn't good quality light.

[ebastler]

But still today, blue LED's are used as the main backlighting for most displays, even though many users have eye discomfort from them. 

Personally I don't notice a problem with the various LCD monitors I use. But it seems that it's not too uncommon for users to perceive eye strain from the blue light. My optician offers glasses with a blue filter which are specifically targeted at computer users. The tint is supposedly subtle enough to not get in the way during other activities (and many people use a dedicated pair of glasses for the medium-distance viewing of computer screens anyway). Maybe worth a try for you if you are sensitive to the blue component in the spectrum?

[Buriedcode]

I don't know if you are a Linux user or not, but there are commandline tools for adjusting PWM on Linux.  Maybe there is something out there for Windows and Mac OS too.  See for example:  https://aur.archlinux.org/packages/intelpwm-udev

That appears to be for laptops.  This makes sense as laptops have aggressive power saving schemes so will adjust the backlight dynamically (like tablets and phones).  It will do nothing for external desktop monitors. I was under the impression you were complaining about all displays.

The backlight has to go through the panel, so adjusting color of the display definitely does have an effect.  You can see this most noticeably by displaying a white page and adjusting colors, but it is very obvious even on a black page. 

What exactly are you talking about here?  Are we still talking about the PWM "flicker" of the backlight? Or the amount of blue light a display emits?  Or is it that the "flicker" seems to affect you more depending on the colour of the display?  A black page will hardly emit any light.  Unless the display is very old, contrast ratios of 1000:1 are pretty common, which is achieved not only by having much brighter displays (because of more efficient LED's and lightpipes) but also better polarisers.   If you notice "flicker" when the display is off (but the backlight on), your monitor is either faulty or very old.

The backlight will always bleed through to some degree, even with VA panels which have considerably higher contrast ratio than IPS and TN panels.  Anyway, most displays that I have seen are way too blue by default.  I see blue screens everywhere I go.  Computers, tv's, information screens, cash register displays, and on and on.  Once you see it you can't unsee it.

Again, are you talking about the colour temperature of the displays?  I rarely see "blue" displays anymore, since it was never a good background colour.  Just because something looks like its "cool white" (which by definition has more blue in it than warm white) doesn't necessarily mean it actually has significantly more blue in it, or that its blue line is a sharp peak.  As I mentioned before, displays are much brighter these days.  Not only that, but your perception changes based on what you're used to.  If you have "warm white" lighting everywhere, then cool white lighting or displays seem much harsher. 

I remember well over a decade now, blue LED indicators were trending in audio gear.  Many users complained of the harsh and glaring light, and manufacturers stopped using them.  They looked aesthetically nice initially, but they weren't so nice to the eyes.  A very common thing for gear using blue LED's was to cover them with black electrical tape.  Oddly, a single blue LED on a piece of audio gear was unacceptable to many buyers of audio gear.  But still today, blue LED's are used as the main backlighting for most displays, even though many users have eye discomfort from them. 

Yes the blue LED craze was awful.  They eyes have trouble focusing on it so it was often blury and glaring.  Thank god they banned them on the front of trucks (at least in the UK).  But this isn't the same as talking about white LED backlights.  White LEDs have a much less pronounced blue peak, and they are not point sources - lighting uses point sources, but a great deal of engineering has gone into making lightpipes that convert point sources into even panels..  I'm not sure why you're comparing bright blue LEDs to white LEDs.

Having a loud high frequency peak in audio wouldn't be acceptable by anyone for audio gear.  It would be deemed as uncomfortable to listen to.  But we have the optical equivalent in LED lighting with a strong blue band dominating the light output, especially with computer displays.  That is why manufacturers have turned to more yellow and dimmer LED lights. 

The audio analogy isn't that great, because if we hear a source with a loud frequency component, our ears "EQ" that to be flatter, so if we listen to bass-heavy music, then "normal" music will sound quite tinny afterwards.  Our eyes (well, brains) DO adjust colour perception, but not quite in the same way.  You seem to think we become more "sensitive" to it, when in reality its the opposite, our brain will adjust to it to reduce it.  Also, as soon as audio gets mentioned in a discussion it goes into the realm of subjective preference and the whole value pseudoscience that inevitably follows 

....  It wouldn't be as uncomfortable to listen to as with a strong high frequency peak, but it also isn't good quality audio, the same as heavily yellowed blue LED's isn't good quality light.

So, how do you know that ALL the white LED backlights you've seen have a strong blue line in them?  I'm not claiming you don't have problems with glaring displays, just that you are doing a lot of hand waving to convince yourself and others that its all about LED's emitting lots of blue light, and the flicker from displays, when there are many MANY things that can contribute/cause eye problems. 

I'm not sure you're going to convince many people that LED backlights, or LED lighting is worse quality without something to back it up.  Measurements, part numbers of devices/displays/bulbs, spectra (which admittedly, isn't easy to get!), scope captures of the PWM if displays etc..

[SiliconWizard]

But still today, blue LED's are used as the main backlighting for most displays, even though many users have eye discomfort from them. 

Personally I don't notice a problem with the various LCD monitors I use. But it seems that it's not too uncommon for users to perceive eye strain from the blue light. My optician offers glasses with a blue filter which are specifically targeted at computer users. The tint is supposedly subtle enough to not get in the way during other activities (and many people use a dedicated pair of glasses for the medium-distance viewing of computer screens anyway). Maybe worth a try for you if you are sensitive to the blue component in the spectrum?

I personally don't know. It's really hard to tell actually, short of doing experiments with and without filters, and see if it makes any real difference for a particular person in the long run.
I would tend to think that the external lighting of the room you're in is more important than whatever your monitor emits. So that, unless you work in very low light condition, I'm not sure it makes a big difference. But that's just an opinion and experience, not a fact.

[Mr. Scram]

Personally I don't notice a problem with the various LCD monitors I use. But it seems that it's not too uncommon for users to perceive eye strain from the blue light. My optician offers glasses with a blue filter which are specifically targeted at computer users. The tint is supposedly subtle enough to not get in the way during other activities (and many people use a dedicated pair of glasses for the medium-distance viewing of computer screens anyway). Maybe worth a try for you if you are sensitive to the blue component in the spectrum?

Again eye strain isn't the issue with blue light. Disruption of the circadian rhythm is as it mimics daylight to a degree your body can respond to it.

[scatterandfocus]

But still today, blue LED's are used as the main backlighting for most displays, even though many users have eye discomfort from them. 

Personally I don't notice a problem with the various LCD monitors I use. But it seems that it's not too uncommon for users to perceive eye strain from the blue light. My optician offers glasses with a blue filter which are specifically targeted at computer users. The tint is supposedly subtle enough to not get in the way during other activities (and many people use a dedicated pair of glasses for the medium-distance viewing of computer screens anyway). Maybe worth a try for you if you are sensitive to the blue component in the spectrum?

I personally don't know. It's really hard to tell actually, short of doing experiments with and without filters, and see if it makes any real difference for a particular person in the long run.
I would tend to think that the external lighting of the room you're in is more important than whatever your monitor emits. So that, unless you work in very low light condition, I'm not sure it makes a big difference. But that's just an opinion and experience, not a fact.

Ambient light definitely is a big factor for me.  Most of my computer use these days tends to be outside on a shaded porch with a laptop.  And it definitely does help for eye comfort in comparison to indoors.  My hunch as to why is that the color spectrum from the LED backlit display is being balanced out to some degree by the natural ambient light.  I intuit this from experience in mixing audio.  In an audio mix, is is desirable to have a balanced frequency spectrum with no major peaks or dips that make the overall audio sound odd or uncomfortable to listen to.  If you take a 'peaky' audio source and mix it in with a fuller spectrum audio source, it can be much more acceptable to listen to.

And what I have seen in spectrum graphs of 'white' LED's (blue LED's with phosphor coatings) is that they tend to either have a too high blue peak (cool LED light) followed by a big dip, or a too low blue peak (warm LED light).

For some very expensive LED backlit displays (I have an old one here), the backlight uses red, green, and blue LED's in order to provide better control over the light spectrum.  But using an RGB backlight is considerably more expensive than using a so-called 'white' LED backlight (blue LED with phosphors coating), which is why they aren't more widely used in computer displays.  RGB backlighting more directly addresses the issue of achieving a full light spectrum at the source of the problem, where 'white' LED backlighting attempts to address the issue after the fact.  Using phosphor coatings for achieving 'white' LED light seems to me to be a lot like using psychoacoustic effects to create the perception of audio frequencies which aren't really present.  See for example:  https://en.wikipedia.org/wiki/Psychoacoustics#Missing_fundamental  It isn't exactly analogous to how 'white' light is being achieved using blue LED's, but if you look at a datasheet for a blue LED (for example:  https://www.mouser.com/datasheet/2/427/tlhb44k2m1-1315895.pdf ) you will see that there is huge blue peak between 400-450nm which is being optically filtered to achieve a fuller light color spectrum for a 'white' LED.  It does seem very analogous to filtering an audio  tweeter (by whatever means) to try and achieve a full range sound.  And it isn't a high quality means for achieving a full spectrum of light anymore than filtering a tweeter is a high quality means for achieving a full spectrum of audio.  In audio, we try to achieve the closest representation of the final sound at the source and use filtering after the fact for minor adjustments, because using filtering causes undesirable phase issues around the bands which are being altered.  But with 'white' LED light (blue LED with phosphor coating), filtering is being used as the primary means for achieving a final spectrum of light from a low spectrum source.  That seems very backward and shoddy to me.  But it is cheap.

To try and more clearly illustrate what I am saying here, consider this:  If we begin with a 3-way speaker which has individual drivers for bass, midrange, and treble, we can get a good full spectrum of sound, which requires some filtering to better balance what is coming out of the speaker (crossovers and eq).  If we instead switch off the bass and midrange drivers and only use the tweeter, using heavy filtering as the primary means for trying to achieve a full range speaker sound, the result will be poor.  But that is the situation for achieving 'white' light using a blue LED.  We don't have a bass driver (red LED) or a midrange driver (green LED) to work with, so we are using heavy eq (phosphors) to achieve something toward a full range sound.  One problem with doing that is that the higher frequencies are going to be most dominant and the low frequencies largely missing (even after extreme filtering).  We can further filter away the highest frequencies, but the overall spectrum is still going to be much more narrow than when using all the drivers in a 3-way speaker.  And the overall volume (output intensity) is going to be much lower than when using a 3-way speaker, requiring using multiple tweeters (blue LED's) to achieve the desirable volume.  And further, there is gong to be major phasing issues across the spectrum. So then it seems to me that the situation for using 'white' LED's is very much like using say, a single driver laptop speaker, instead of a proper 3-way speaker.  The 3-way speaker is going to much better give a fuller spectrum, higher volume of that fuller spectrum, and much less phase issues than when using a single small driver to achieve a full spectrum.   

Apologies for the many edits. 

[SiliconWizard]

Yeah, to sum it up a bit, ambient light is a big factor here when using displays in general.

And yes, white LEDs tends to have a spectrum that's closer to sunlight (except for the UVs, apparently most LEDs emit very little, or almost no UV at all) than your typical incandescent bulb, so yes it can cause issues to the circadian rhythm at night time.

Humans beings are not the sole "victims" of this. At places they put outdoors public LED lighting, you can notice that birds can get bonkers and start singing in the middle of the night. I've noticed it in my area. Sure the spectrum is not the only problem; brightness is often way too high.

[scatterandfocus]

I haven't had any sleep issues from using LED backlit displays or LED lighting.  Maybe some people do, but I never heard of it in person happening to anyone.  I have asked around at work before to find out who gets eye discomfort from computer displays (all the displays at work are LED).  Literally everyone I asked said that they either get bothering discomfort or eye pain from working with them, but maybe it would have been the same for CRT's or CFL backlit displays.  And a couple of people told me that they are bothered by the fluorescent lights, too.  The fluorescent lights at work do bother my eyes some, but not nearly as much as using LED backlit displays.