In my backyard there are some street lights for everyone to use when it's dark, so people find their garage and car. I found whenever they used the lights, which turn off automatically after 5 minutes, I O eye strain that persist for 1 hour+. The light that was coming into my room was very subtle. However, I made sure to buy light-blocking roller blinds and curtains to minimize the light.

Edit: A long text got destroyed because my phone's battery died. And I typed it on the phone. I'm not typing it again. Short form: suddenly eye strain in a dark room with everything closed, windows behind me, looking at the bright (known-good) phone screen. I look outside and realize someone has turned on the streetlights. A small reflection on the wall and ceiling caused the eyestrain. The lights flicker at 100 Hz. The reflections are very faint plus not remotely visible when you look at a bright screen.
I'm telling you this to raise awareness that even slightest changes could cause eyestrain. FRC, temporal dithering, the LED bulbs I tried, their flicker is extremely low. Yet they cause trouble. I blocked blue light on my bulbs and verified it was truly blocked with a spectrometer. Blue light is not their issue. Only the flicker remains. And even very low percentages of flicker seem to cause eye strain.

2 months later

Solf that bulb flickers at a rate of 220/2 = 110 times per second. I assume it's 220v AC current ur using. Most phones and screens if I remember correctly flicker anywhere been 800 to the thousands per second with PWM or oled.

  • JTL replied to this.

    Doesn't an regular old-fashion lightbulb flicker because of AC current? Yet most people aren't bothered by them here?

      ryans Yes, they flicker because the power network in our countries is constantly switching the current direction and no attempt is made in either lamps or bulbs to convert AC into DC.

      I have trouble with some incandescents. It is not caused by the bulb per se. Must have to do either with the lamp electrics or how the light reaches the eye. My bathroom light is always good, my living room light hurts a little over time, and the very bad IKEA "Holmö" lamp that I have bought a while ago gives PWM symptoms immediately, even when the light source is out of sight. Couldn't measure any differences yet on oscilloscopes, but it's hard to do precision measurement on ceiling lamps.

      ryans should only glow 60 times a minute. Or 50 if you use Pal. I heard the biggest problem people were having with these is really cheaply made rough service bulbs. I know two people this was causing eye strain to.

      • KM replied to this.

        KM

        KM I never knew that. No incandescent has ever bothered my eyes. I don't know how I did function otherwise.

        KM I think this raises a very interesting question. Why is 100x a second flicker in a light bulb fine, but, 220 Hz OLED flicker is not?

          ryans I don't know the answer. One could argue that the 240 Hz OLED PWM has a larger flicker percentage (the difference in amplitudes) or in general a faster rise/fall time. But ultimately, no solid theory.

            KM

            ryans You are not looking at the light bulb directly.

            Also what hurts you in the oled might not be the pwm, but the dithering of the OS.

              4 months later
              9 days later

              Yesterday I replaced a dead incandescent bulb in my kitchen with an LED bulb that doesn't flicker to the point where only more sophisticated measurements reveal 0.06% 100 Hz flicker without any warm-up phase (some other bulbs flicker terribly until they've warmed up). The light intensity is very low at 200 lm. The light itself is very orange, much warmer than any incandescents. As the orange color already indicates, a handheld spectrometer shows only negligible amounts of blue light. After some minutes, the light begins to stress my eyes nonetheless. I woke up with burning eyes today. It remains a mystery why LED bulbs are not usable for me. The E14 small version incandescent bulbs had strong 40% 100 Hz sine wave flicker and seemingly more blue light, but were usable.

              And my good old bathroom lamp "IKEA PULT" died, so I replaced it with the latest PULT version and the regular incandescent bulb inside it suddenly triggers symptoms. I never knew why the old lamp was so comfortable to look at and I don't know why the new version triggers eye strain. I looked at the electronics and found there most probably are no electronics at all in both lamps. Instead, the ceiling cables go directly to the bulb socket. A difference is the new version has a frosted glass cover while the old one had a milky one. The measurable flicker hasn't changed, still 25% 100 Hz sine waves as usual (60 W bulb).

                KM The light itself is very orange, much warmer than any incandescents. As the orange color already indicates, a handheld spectrometer shows only negligible amounts of blue light.

                Sounds like the lights in my office, although LED. So what now, are we sensitive to the orange color?

                What about the PULT? Is it incandescent and still hurts? What about the color?

                • KM replied to this.

                  AGI PULT is just a ceiling lamp with a regular bulb socket that you can put any bulb in, be it incandescent, energy-saving, or LED. It has a glass cover, but the color is not changed by much.
                  https://m2.ikea.com/us/en/p/pult-ceiling-lamp-steel-10193300/

                  I'm sensitive to all LED bulbs I've seen so far regardless of color (orange up to bluish). Some are extremely aggressive and some less. But the "blue light" and "flicker" theories are maybe not enough to explain problems with orange and (almost) flicker-free bulbs.

                    So what happens when you switch the cover from the old unit to the new unit?

                    KM I had an incredible conversation with the head guy at the blur busters website. I think he may be the leading guy on the internet on why screens and LEDs are as problem. Alexander Wunsch and Dr Arnold Wilkens have nothing on this guy. It sounds like most of us will be waiting till the mid 2020's till LEDs are safe for us. Here is the link to the conversation hope it helps. https://forums.blurbusters.com/viewtopic.php?f=2&t=5361&start=0

                      11 days later

                      Did anyone ever try CRI 97 or higher LED bulbs? I just checked all my bulbs and found they all are labeled either "CRI >80" or "CRI >90". I have been ignoring this spec and dismissing it as unimportant up until now. Could it make all the difference? New quest: finding an LED bulb that is both flicker-free and has CRI 97+? At least the latter info is usually written on packages.

                        dev