PSA: LED-Backlighting Can Cause Migraine Headaches

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A little over two-years ago I began experience infrequent, but regular migraine headaches. Before this time, I had only experienced three or four migraine headaches in my whole life. They began a few months before I started law school, and they were happening about every two weeks.

I started reading some literature on migraines, and learned that for some people, the headaches are “triggered” by some stimulus to which the person is sensitive. I was at a loss however, as I could not correlate the onset of my headaches with any particular stimulus. I saw a doctor, who seemed convinced that the headaches were stress-induced (first-year of law school, growing family, etc.). I disagreed, however, and continued to investigate.

One day, I suddenly came to the realization that the headaches began around the time I purchased a new laptop computer for school. I had never had any problems using any computer before, so it never occurred to me that the purchase of the computer might be related to the headaches. After some googling, I found this thread on, and a related thread on Lenovo’s forums, where others were reporting migraine headaches related to the LED-backlighting on the Lenovo X200 Tablet. Like most laptops sold today, my laptop, a Lenovo X200 Tablet, had an LED-backlit display. It seemed that I had found a good candidate for the cause of my headaches.

After some further investigation, this is what I have found:

  • LED-backlights in most laptops do not generate constant light, rather, they flicker (flash on and off, like a strobe light) at a high frequency for most brightness levels.
  • The flickering of the LED-backlight seems to serve two functions: (1) it saves power, and (2) it is used to control the brightness of the display.
  • There are a couple of relevant characteristics to the flickering: (1) the speed at which the LEDs are turned on and off (frequency), and (2)  the amount of time that the LEDs are off, versus the amount of time that they are on, during each cycle (pulse-width).
  • The brightness of the display is adjusted by changing (or modulating) the pulse-width, i.e., the LEDs are turned off for more of the time than they are turned on. This makes the display look dimmer.
  • It would be possible to drive the LED-backlight with circuitry that does not flicker the light, but rather make the LEDs always on. This is not typically used, however, because the circuitry is either more expensive, or less precise.
  • The flicker of the screen can be verified by viewing the laptop display through the LCD viewfinder of a digital camera. Because the frequency of the camera is not in sync with the frequency of the LED-backlight of the display, the display will appear to flicker through the camera.
  • The Lenovo X200 Tablet uses an Intel integrated video chip, and by default the drivers for the display flickers the backlight at any brightness level lower than the maximum, and even if the brightness is at the maximum, if the laptop is operating on battery power, then the display is flickered (as a power-saving measure). However, if the laptop is plugged in to AC power, and the brightness is set to the maximum, then the LEDs are not flickered, but on constantly. Also, there is a setting in the Intel driver software to disable the flickering for the maximum brightness setting when on battery power (though it is obscure: in older driver versions, you had to turn off “Intel(R) Display Power Saving Technology”, in newer version you have to change the battery power plan settings to “Maximum Performance”).
  • Different manufacturers use different frequencies for their LED-backlighting. Someone reported on the thread that the X200 frequency is 90Hz (which is very low), while Fujitsu uses 500Hz.

It is not clear what aspect of the flickering induces migraines. It is, no doubt, different for each person that experiences this phenomenon. It’s not really surprising either, since it is well documented that some people have migraine sensitivity to flickering lights, such as florescent lights. (Note that previous display technology used florescent backlighting, at frequencies around 100Hz, however, a florescent light does not turn off almost instantly like an LED, and so the flickering is a little less significant.) Some people have had sensitivity to older florescent-backlit displays too, especially if they operated at lower frequencies. These people are in for a world of hurt as incandescent bulbs are outlawed in many parts of the world, and CFLs or LED lights are the only thing available.

At any rate, upon learning all of this, I set the display brightness of my laptop to the highest level (and I keep it there always!), and adjusted the driver settings so that even if I am using the laptop on battery power, the display is not flickered. Since that time (almost a year and a half ago), I have not experienced any more migraine headaches. My migraines were clearly linked to the flickering of the LED-backlight in my laptop, and I was not even aware of the flickering. The flickering did not act as a traditional “trigger” (in other words, it did not immediately induce a migraine), but over the course of a couple of weeks of use would give me a migraine. Everyone is unique; some people who are sensitive to the flickering get migraines within less than an hour of using the display.

Hopefully this dump of information will be useful to someone else who has experienced similar issues. It is bound to become a bigger issue as all manufacturers are moving over to LED-backlighting for all displays. Pretty soon all computer displays, all TVs, and all light bulbs, are going to be using this technology. It is possible that I am only sensitive to my current display because it operates at a relatively low frequency. This is hard to investigate though, because the data about the frequencies at which these backlights operate is very hard to come by. It is never disclosed by the laptop manufacturers. I hope that this will change in the future, for the sake of all the potential migraine sufferers out there.

49 Responses to “PSA: LED-Backlighting Can Cause Migraine Headaches”

  1. ken

    They should responsible to customer health. When it come to dimming, I can see it flicker from my bare eyes and it really hurts. Anything is flickering when its dim including desktop monitor and my cell phone. Can anyone suggest a brand which does not flicker, please?

    • Scott

      This thread reports on a Sony and a Fujitsu that have LED backlights running at 500Hz PWM. In the same thread, someone reports that the Lenovo x200t has a display that runs at 90Hz PWM. (The 500Hz is going to be better for a person who gets migraines from these kinds of displays.) However, I don’t think there is any way to be sure what type of display you are getting from any particular manufacturer, because of the way parts are sourced by these companies. I imagine the same model could have different displays depending on when and where they are manufactured. The only way to know is to probably test it yourself.

      • Shay

        Usually it’s just the LCD panel that you don’t know the design/manufacturer of. The LCD panel itself just has the backlights in it, but without the driver electronics. The backlight control is almost always part of the monitor design, and thus doesn’t change for a given monitor model. So if you find a given model has a high PWM frequency, even if they change LCD panels over time the PWM frequency shouldn’t change.

        A good test for low PWM frequency is to lower the monitor’s brightness, display something light-colored on screen, and wave your hand. If you see distinct after-images of your fingers, it uses a low frequency.


      You might try something for the flicker-I did this–lower the refresh rate from 60 htz to 59 htz-on your monitor.
      It worked for me-I suspect each of us has a frequency that we are more susceptible to –that was mine.
      I feel that was a weird result-I would have thought that faster would have been better but it was not.
      I had severe aura without the pain–but it was totally shocking-was so confused that I called an ambulance. Doctor checked me out-no results but my optometrist suggested that aura was the issue and I went looking for solutions-That is what I came up with. In 6 months since it first happened, it happened 2 more times but insignificant as to affects . Nothing since I lowered the refresh rate.

  2. Bob

    Regarding eye strain and headache due to led backlight….

    I do have this problem with new my MacBook Air, and it generate a great discomfor, at the beginning after an hour of use, and now after 10 minutes!!!

    The cause seems to be the low frequency of the led backlight. The light emitting diodes are turned on and off at a frequency (around 60 times? per second) which is to low inducing a non visible but real flickering which affect the sight, sensible eyes trying to adjust 60 times per second!!!

    There are various systems to activate the diodes, some (pattent) are electronics with higher frequency.

    The same brand or same model of computer screen can maybe have different system installed but manufacturer will not tell.

    High led backlighting frequency will solve the problem…when manufacturer will install it.

    As I am not ready to risk irreversible sight damages, I shall return my MacBook for loss of screen comfort.

    I am confident Apple will solve this problem.

  3. Craig

    I am sensitive to both flicker and fluorescent light. So I can’t use an old CRT due to flicker or regular LCD due to the CCFL back lighting. I thought LED was going to save the day until this flicker issue came up.

    I have replaced both my monitors and TV with LED versions. I just keep the brightness at 100% to reduce flicker and wear sunglasses. Yes, it sounds funny, but what do you do.

    I also calibrated my monitors and TV to optimize the display. I am sure the 100% brightness will burn out the display sooner. So much for power savings 🙂

    I am hoping that this is a short term problem and a better solution for dimming the LEDs is found.

  4. MLange

    There appear to be lots of posts on the internet regarding screens that cause migraines. While there have been lots of reports about which screens cause migraines, i have not come across reports from people mentioning alternative screen models which work. Have any of you found new laptops or lcd screens which do not cause migraines? If so, what is model number? I found a report online from some guy in Russia who built an incandescent LCD, but i don’t have time to experiment with that at the moment. I am not interested in what people think will work or what their theories are on what should work; rather, i want to know what people have tried that has worked, from experience- this to me is the gold standard.
    Also, i think it’s worth mentioning that a screen’s refresh rate can be limited by the type of video card that is used. I’m not super computer savy, but it seems that a monitor that is hooked up to one computer and not cause migraines on that one can cause migraines when hooked up to another computer with a different video card.
    Lastly, there are lots of posts out there about is topic, and there are lots of bright people who are affected by this problem. Perhaps we can consolidate our resources and start achieving more effective solutions to this problem if we could create some kind of group dedicated to practical solutions to this problem. People in the rest of society are skeptical of our problem and frankly we are the only ones driven by a need to fix this problem, so perhaps by looking to each other we can achieve a common goal that will, no doubt, allow us to live fuller and richer lives.

  5. daniel

    I had no idea that I could turn off the flickering by setting the brightness to max. So thank you very much!

    • Jesse

      Absolutely, thank you for the full brightness info, I just witnessed this through my cell phone camera and no flicker at full bright on my laptop!!! They just installed LED lighting in the factory I work at and it is intense, I have been getting Migraines everyday since these were installed and need to find a solution before I loose my job….

      • Scott

        I’m sorry to hear about the lighting at your work. I am scared of what is going to happen as LED lights become more widely used.

        • Jesse

          There are in my fridge at home, I have to close my eyes when getting anything and try not to look directly at them:( I read through this Ukrainian gentleman’s web page and it left me with many questions, I am scheduled to visit a neurologist….

  6. David

    Thanks for the article. This whole issue is due to Pulse Width Modulation. It’s a more accurate way to reduce brightness but has the side effect of causing headaches in sensitive people. It is more prevalent in LED monitors. I bought an LED and my migraines went from 1 every other month to 2 per week. I will be switching back to a standard LED and hopefully that will help. There is a website where someone in ukraine posted a summary on this issue:

    Also, I’m hoping that the OLED technology does not feature pwm to control brightness. I’m unfamiliar with how OLED’s work but we are still a few years away from affordable OLED monitors. Right now they are about 13,000 US for a 17 inch version.

    • Scott

      Thanks for sharing that link. That is a great resource of information on this issue. Flicker does seem to be the main problem for people experiencing eye strain and headaches. I am guessing that many more people are affected by this than realize it. Hopefully awareness grows, and some other options become available.

      I have not looked into the technology yet, but I too am hoping that OLEDs do not use some type of flickering to adjust brightness.

    • Henk Poley

      The guy has literally split apart an LCD and put an old light bulb behind it.

      There must be more efficient non flickering light sources though.

  7. Osama Abdullah

    Could you please advise what I have to do because I have the same problem and if you could advise me which type of laptop doesen’t have this problem so I can buy it.


  8. Anycorpse

    OLEDs are gonna use PWM for dimming. They simply color shift too much when dimming with current control.

    However if we all keep pushing this issue about PWM some manufacturer is eventually going to pick up on this and make settings and options available to remove dimming even if it causes color shift. Technically its not difficult or expensive to do. Its just a matter of will to do it.

  9. Ann

    Just bought an LED TV, couldn’t find a decent LCD TV anywhere. I now have headaches, no migraines yet, what a bummer, after 5 minutes of watching TV I have a headache. With all that flashing of LED lights no wonder it is causing headaches, migraines, nausea, etc. There must be millions of people affected by this problem. I think I will swop my brand new TV for my son’s older LCD TV and solve my problem. Thanks for all the info.

    • Jesse

      LCD and LED bothers me however glasses with Anti-glare coating makes it easy for me to watch LCD TV’s with florescent back lighting easily for hours or be in stores with Fluorescent lights. LED lighting is terrible and I do not know what to do about it yet, I have tried the Phillips “incandescent” LED replacement bulb that has a spectrum of 2600K which is the same as an incandescent bulb, I believe you can rule out the color being the cause but bright white/blue LED & florescent lights are quicker to trigger my head aches than filtered lighting with a warm spectrum. I am pretty certain there is a wave length issue or strobing effect from LED’s that makes them efficient at the root of the problem, it may be possible to filter out this issue with some sort of specialty lens….

  10. Leah

    The newer TV’s bother me. I get such a headache. I agree with Jesse, I have the antiglare glasses, that transition. However, if I am at home, relaxing, I am not trying to have my glasses on all the time. I need a new tv, but if I have to buy someone’s used, I will. I am not electronically skilled. I don’t want to try to take a computer or tv apart. Is there a place where people can buy electronic items that don’t flicker anymore? People with headaches or seizure disorders?

    Thank you

    • Jesse

      I agree, it is inconvenient to wear glasses all the time when you do not need to however I would rather that then the headaches…I do not know of a place that sells TV’s for people with these issues, I would say that is unlikely to exist because people who have issues are a relatively small % of society. I am continuing my pursuit of answers by seeing the Neurology department at DHMC here in NH, my next appointment is to be with a headache specialist. I have also decided to start a blog and I will post a link to that when I get it up and running, I feel we need to collect our efforts and have a central hub of information for this pressing issue. Leah, I would be curious to know how you feel around LED lighting, is there a store or gas station with these where you normally go? It would be interesting to know if you react the same way I do….

  11. James

    Thank you for this. I knew my tv was a trigger for my migraines and couldn’t figure out why. This has been a huge help.

  12. NeRD

    Thank you. I don’t know what type of display is inside my iPad mini, but turning the display all the way up made my migraines go away instantly. I’ve had headaches every morning and evening since I bought this. I was so fed up with the headaches that I turned to google thinking it was a goofball decision. This page was the first result. I was using the display at 50% during the day, and 10-15% while in bed.

    Thank you very much. Happy Holidays, everyone.

  13. chasmyn

    Thank you for this. I have been having problems with migraines first when we replaced all our bulbs with CFLs (then took them out when migraines started happening); and then with the introduction of LED laptops and TV and smartphones into our home. I knew fluorescents exacerbated my issues, and I had a concussion earlier this year which really sent everything over the edge. According to my neurologist, I am supposed to be recovered by now, but I am not, and have been trying to figure out what is going on.

    Recently my family went for a three day trip without my laptop, and in Canada so we were roaming and couldn’t use smartphones. Despite having been under fluorescents for several hours, having little sleep and having driven for seven hours, I was migraine-free. Until the next day when I was on the screen playing catch-up, and then today (the day after that) I am down with a migraine. And that’s when it clicked – it’s the screens.

    Which ironically I needed to use to find this information to follow my hunch. Thank you.

  14. systemBuilder

    The backlight is a huge consumer of power, and the only way to actually save power with present circuitry is to turn it off by cycling it on and off using PWM. Software solutions that leave the backlight running at 100% and then dim by dimming each pixel on the screen, will not conserve energy on the laptop. LEDs have a nasty problem in that you have to get over the diode voltage drop in order for them to work at all, and so the diode has a minimum that might be 0.6/3v = 20% of maximum light, and so you have an absolute minimum brightness of 20% and probably much higher in practice (due to diode manufacturing tolerances, etc.) if you were to do voltage-based dimming.

    I think this means that a voltage-based dimmer can’t get the LED dim enough to truly save lots of juice, thus PWM dimmers are here to stay for the foreseeable future…

    • Migraine Newbie

      My contention is that my laptop is a desktop replacement, so basically I sit at a desk, plug in my computer, use it, then I move to a different desk, plug it in, use it more.

      These PWM-obsessed manufacturers are hung up on saving power… WHEN I NEVER USE THE BATTERY. It’s just backup power in case of an emergency outage, so I have time to save my work. When I bought this machine I knew it was a power hog and never wanted to sit outside in the sunshine to typey type with a 150 degree laptop chassis burning my legs. I sit in air-conditioned offices like most people. I needed a mobile desktop computer because I have more than one air-conditioned office to sit in, not because I wanted the freedom to spin circles in my chair.

      I hope someone eventually offers a laptop with a flicker-free display. This is killing me.

  15. systemBuilder

    It might not be PWM that’s the actual problem, but rather, it might be the PWM frequency that’s causing the problem. Smart laptops should allow people to increase the PWM frequency (i.e. from 50 Hz until 500 Hz, for example.)

    • Scott

      I think that this is likely the case, but it is hard to know without more data. I wish that PWM frequency information was available from manufacturers.

  16. Georgiann Durrenberger

    Muscle tension can cause headaches and by relaxing muscles, especially in the neck, it is possible to relieve migraine headaches. Once the technique is learned there is no longer any need for the biofeedback equipment. The patient with migraine headaches can now produce the desired effect any time they wish. Sometimes too much salt can cause headaches. And by simply lessening the salt intake headaches can sometimes be prevented. Some migraine headaches are caused by food sensitivities. Certain foods can cause migraines and eliminating these foods can prevent migraine pain. Some common foods that can trigger migraine headaches are cheese, alcohol, monosodium glutamate (a food additive), nuts, beans, caffeine, chocolate, onions and others..

    My personal web site

    • Tim

      That’s another point, there are so many many things that are supposed triggers, it’s almost impossible to determine what actually triggers it. I get chronic migraines myself. There are also a zillion “cures” claimed by some, which are BS. Doctors don’t even know why migraines occur.

  17. Tim

    I think this article is making a lot of assumptions with no proof. How can you say it causes them, yet you see no flicker and can get a migraine a couple weeks later? Sorry, but that does not make it a trigger. A trigger would happen within hours of the trigger, not days or weeks.

    • Scott

      What I am doing here is simply providing information regarding my experience with migraines. I have not purported to prove anything, but I have offered evidence to support my hypothesis. My evidence is that when I used the dimmed LED backlight I got migraines regularly for months, and when I stopped using it I did not have any more migraines. Everyone is different, and this is clearly not everyone’s experience.

      Further, I acknowledged in the post that this is not like a traditional trigger, because the migraines are not induced immediately (at least for me). However, it is certainly conceivable that this may be a cause of migraines, since, as you note above, “doctors don’t even know why migraines occur.”

    • Jesse

      Tim, if there is a person that can confirm LED back lit displays and general LED lighting trigger migraines, that person is me. My symptoms are instant and I may be the most severe of anyone I have met so far, I have through many measures found the “Stobbing” effect and the Blue light hazard of LED’s to be the cause of my issues, there is not an LED light that does not give me severe headaches within minutes and I become sensitive to light for days after exposure. I have found that there is not only a PWM effect but also that LED’s are capable of 0% power fluctuation where Fluorescent lights are only capable of 50% power reduction during frequency modulation (I would have to assume gasses do not react fast enough for greater power fluctuation), thus the stobbing effect of LED light is intense when coupled with the extra brightness level and blue light issue. The French have done a study that found LED lights in one of their schools were actually harming the vision of young children, a lighting expert named Howard Brandston mentions this during a hearing, I believe we are yet to see the real health hazards of this new lighting and it will be some time before we do because there are 0 dollars invested by our government in any research to protect the consumer here. In addition to that issue the government is actually pushing energy efficient lighting and investing in it.

    • Nikki

      Sorry Tim but there are a lot of us that get migraines and even seizures from LED’s. All I have to do is walk into an electronics store and LOOK at one of the LED’s to start feeling the throbbing in my head and nausea. It does not have to be just LED backlit as most monitors/tv’s now are all LED. The only type of tv’s/monitors I can deal with are LCD 120hz at 60hz my eyes strain and I get a headache (not a migraine). And to the refresh rate there is ample studies/evidence to say that the flicker causes eye strain, headaches etc.

      • Jesse

        I am not sure if this site is still being maintained? There is some great info here and several people speaking about the exact issue I am going through. I have created which is a work in progress right now but its out there and growing so feel free to check it out and join the ranks of people who understand what you are going through!

          • Jesse

            Thanks Scott! Everyone can find it here:


            Please be patient while I learn to create the best website experience and sharing of information for everyone, I hope this will be a great place for us to gather our efforts!

  18. Stanillee

    What laptop do use that is tolerable even at 100% brightness. I am struggling to find anything that doesn’t give me instant nausea eyestrain followed by migraine headaches for days.

    • Scott

      I am using a Lenovo x220 Tablet right now. The tablet has the advantage that the screen brightness is a little muted by the touch screen layer. I have found that, for me personally, my migraines are not triggered by the brightness of the screen, so it’s not as big a consideration for me. It sounds like for you, though, your migraines are also triggered by screen brightness. If that is the case, you may have a more difficult time finding something that works. Do sunglasses help? Good luck, and let me know if you figure out something that works.

  19. Craig

    I’m once again on the hunt for a flicker free monitor and came across these two items I thought might be useful to others…

    Flicker Free Monitor Database

    BenQ banishes screen flicker with new monitor range

    Maybe the industry is finally starting to head in the right direction with the LED technology.

  20. Ian

    I am so grateful that I have found this website.
    Last month I purchased a Samsung Galaxy Note 10.1 WiFi tablet. It was my first tablet purchase.
    OMG! This thing very quickly started causing my horrendous Migraine/Headpain, that would start around the inner ear, temple & behind the eyes in a band type distribution that spreads through my head & gets worse over the next 30 mins or so after finishing usage of the tablet. The migraine effect can last several days, depending on how long I use it.

    I’m a electronic technician/engineer who suffers from Chronic Fatigue Syndrome & some EMR sensitivity from such things as mobile phones & DECT cordless phones. However the effect that this tablet was having on me in terms of the both how quickly I was being effected & the severity far exceeded the EMR effect from a digital mobile/cell phone radiation.

    What exactly on this tablet was effecting me I asked? I turned off the WiFi & GPS. Still effected. Was it the refresh rate or the EMR S-Pen technology that this tablet employs?

    I had to find answers?
    I employed the assistance of a Kinesiologist.
    EMR was a small part of the problem, but it appeared to be something to do with the light & flicker/refresh rate from the device.
    The kinesiologist diagnosis resulted in so many neurological parts of the brain being effected. The clearing effect had me suffering detox symptoms for 5 days! Next visit I asked more questions about the tablet to the kinesiologist. A figure of 47Hz came up in regard to refresh rate or light pulsing. That was low I thought. I need some kind of tech spec to verify this.

    I do get effected by LED PC Monitors & old CRT monitors. I can’t use old 60Hz CRT monitors, but I was able to use an old 85Hz Sony CRT monitor up until 3 years ago for short periods. I’m one of those people that do see 60 – 75kHz CRT refresh/rastor flickers & became affected by PC monitor usage not long after getting sick with CFS.

    60Hz LED monitors were effecting me also. I have a 120Hz Samsung monitor that I can use for longer. But this Samsung Galaxy Not 10.1 was affecting me some x10 worse than anything else I’ve experienced.

    It didn’t dawn on me (until reading your blog) that to effect LED backlight levels, that pulse width technology was employed, nor did I know that various manufactures use different backlight pulse frequencies. I find nothing in the Samsung tablet specs about this, so I will try to contact them.

    I can turn off the battery saving technology in the Samsung & I can set the brightness to maximum, however with diagloge boxes that pop up on the screen of this tablet, the dialogue box stays a max brightness, but the rest of the screen dims, what is happening here? I also need to find out what differences if any occur when the USB power feed is connected. I need to experiment with this.

    Before reading/finding your blog I was at the point of selling this tablet. It still may happen. I had left the device untouched for weeks due to the migraine headache effect it has on me.

    I’ll keep you all informed of my progress with Samsung, my further personal findings & see if my optometrist & Dr’s can assist me in anyway with this problem & with the knowledge discovered here.

    I’d also like to say that not only do I get a horrible migraine, my cognitive functioning deteriorates as well due to the sub-concious light flicker.

    Does anyone know if any TABLETS are made without the LED screen flicker/pulsing?
    Pleased to hear that BenQ are now making flicker free monitors. For the record I tried one of their (flicker) earlier VA 60Hz screens a few years ago. The text rendering was horrible compared to Samsung’s TN panels & the VA panel was only good if your were positioned exactly in front of the screen. That said the blacks were very nice on the VA panels.

    Any feedback welcome. And I provide further info later.

  21. Ian

    RE: “…..that do see 60 – 75kHz CRT refresh/rastor flickers”
    I meant to say 60-75Hz 🙂

  22. Ian

    Some feedback for you all.

    Visited an Optometrist & was prescribed a set of carefully scripted reading glasses.
    I will say that this did help the situation in the following ways:
    I can use the tablet about 50% longer in duration before migraine effects start, but that’s not much, when I become notably effected in less than 10mins.
    I don’t feel nauseous using it anymore & I recover from the migraine effects quicker.
    BUT that said, the effects of this tablet are such that I will have to sell it.

    I have tried contacting Samsung on a few occasions & each time I get nowhere with their technical support people (Hello Samsung) in regard to determining the backlight frequency & pulse-width data.

    The only bit of meaningful data I received from them is that the screen refresh rate is guaranteed to be higher than 40Hz. Given that the screen is capable of maximum of 60Hz, that makes the (non-technical) Kinesiologist’s figure of 47Hz look pretty good.

    As a test for comparison purposes I placed a large electric fan in front of a) my Samsung 120Hz monitor & b) the Samsung Tablet. Only upon turning off the fan & watching the screens, each in turn, through the fan blades could I see what was going on. Results: a) with 120Hz monitor, just a bit of flicker as the fan blades were coming to a stop. b) with the tablet, as the fan blades were coming to a stop I started seeing bad flickering & all these colours in the centre of the screen flickering & then as fan blades got slower I started seeing small coloured pixilation dots all over the screen. The effect was absolutely horrible on my eyes/brain.

    I’ve seen on the Internet where, with use of a digital camera, where you know or can alter the shutter speed you can calculate the screen backlight frequency, but I don’t know this for my 2006 era digital camera. I would like to know what the frequency of the tablet so I can possibly compare to other tablets, but it seems unless someone goes to the trouble of measuring these frequencies & publishing them, it’s going to be difficult to make an informed & comfortable choice of monitor or tablet.

    Comments welcome.

  23. L Mcc

    I’m a PC tech and have always followed technology closely for 12 years or more(since I became divulged and obsessive with it.) Even before I used computers I had headaches in public school all through growing up, enough to make me not pay attention, keep my head down, and guess through all my work.

    When I started working with computers, the CRT monitors gave me no issues whatsoever. However, shortly after getting a new 24″ CRT monitor I began experiencing headaches after a few hours of gaming or more frequently, about 10 minutes during reading text in IRC(Internet relay chat), since the web wasn’t as big as it is today. Someone whom I talked to who worked in the tech industry as an ISP admin told be about the monitor Hz being the likely cause. By default the refresh rate of this new monitor was 75Hz. I adjusted down until I found a comfortable setting, which was 60hz. No more headaches, no more issues.

    Later down the road my uncle upgraded all his PCs to early LED monitors. I was over for a few hours while my cousin, uncle and my self played over lan. These monitors were ridiculously hard on my eyes. They watered, and I could feel them burning my retinas. Needless to say, I didn’t get an LED/LCD monitor for quite a few years. 3 years ago I upgraded my system and got a 24″ LCD display. Only because CRTs were out of style, I don’t like to be too far behind on tech, and many gamers and techs I talked to said it had the best longevity over other technologies. The monitor I purchased was similar to and by default it was 60hz. There is no other setting on it. I work, game, and more on it. (16+hrs) I couldn’t be happier with it. Not a single headache, not a single issue. I use it for everything.

    Recently I had bought a 32″ Philips LED, hoping to use it externally for movies, or a secondary display.
    I couldn’t use it. After a movie my eyes couldn’t take another second looking at it. I had it for a few weeks and I just hated it. I realize that anything over 24″ 1080p stretches, but that wasn’t even a problem. Jagged text, headaches, and horrible unrealistic contrast to go with it, no matter the distance I sat from it. I GAVE it away. A friend of mine has that 24″ Playstation/PSP 1080p LED monitor/tv, I can’t look at it too long either. He boasts that everything looks crisp and sharp for him, with no issue. But I just see bad contrast and jagged text, aside from the eye strain.

    People may like LED, but I say they can keep it. I’d rather not burn my eyes of my sockets and actually get realistic colors for 8-bit colour animations.

    Note: I wear glasses, and only have -0.23, I ain’t as bad as others, but my eyes do over focus from using computers longer than most people have in their lifetime.