deepflame Hmm, and I assume the "bad fluorescent" line matches the ones of the good one? If so, this is really strange indeed. Maybe some flickering then?

That is right, and that is what frustrates me.
I do not get how I can perceive warmer light if the spectrum is the same. I got the doubt the paint of the walls and the furniture, which are all brownish/reddish, plays a role, but I asked other people, and they confirmed the light is softer in the office than in labs. I guess it is supposed to be more relaxing. Not for me. You should see, after a minute at work on Monday my eyelids start twitching like crazy.

I was unable to measure the frequency. I am speculating that the bad lamp outputs lower power light with the same spectrum of the "good" lamp, and at lower power the radiation flickers more, a bit like for PWM-controlled displays if the brightness is lowered the switching on and off of the back-lights becomes more frequent.

      AGI This is one of the weirdest things I have heard so far. I mean CCFL backlit screens for example tend to be better than LED screens as well.

      Maybe there are other light sources than the fluorescent tubes that cause the twitching? Maybe even the screen itself?
      Thanks for sharing this...

      • AGI replied to this.

          deepflame This is one of the weirdest things I have heard so far. I mean CCFL backlit screens for example tend to be better than LED screens as well.

          My analogy to PWM-driven control of the brightness is likely incorrect. I read a bit about electronic ballasts and thought that at low power they may behave in a way my eyes/brain are hypersensitive to. But, as I said, the fluorescent lights in my kitchen and living room visibly flicker and are blue-shifted. No pain.
          I am confused. Can high frequency flicker bother more than visible one?

          deepflame Maybe there are other light sources

          For sure, my iMac is not smooth on my eyes. I can use my MacBook Air fine at home and not at work, though. I have problems just standing under those lamps, or reading on paper. But, yeah, ruling out variables is hard because my symptoms are long-lasting.

                7 days later

                deepflame Hmm, are you sure these are fluorescent lamps? I have seen mostly LED tubes recently here in Germany. Not sure if they sell normal fluorescent tubes anymore.

                Hey, I thought of sharing additional details I got, in case you and/or someone else is interested.
                All the lamps I tested, "good" and "bad", are of exactly the same type (Panasonic FHF32EXLH), which explains why with the spectrometer I did not detect spectral differences.
                The light color is called "electric bulb" (there are eventually other variants with different colors, e.g., natural, white, etc. etc., which are not installed anywhere at work, as far as I know).
                https://global.rakuten.com/en/store/denkyu/item/n048hf32exlh/

                From another document - which is only in Japanese - I see (ehm, I guess) that the color temperature is 3000K.

                Looking more deeply at the specs I infer that there are either two subtypes of FHF32EXLH lamps or the same tube can be run two ways, low and high power, namely, 32W / 0.255 A / 3520 lm / 3000 K and 45W / 0.425 A / 4950 lm / 3000 K, respectively. Note that the color temperature is the same.
                The facility people who take care of the lighting confirmed the lamps in the office ("bad') are dimmer than the ones in the labs ("good"). Hence I conclude that the "good" lamps are the high power ones, and the "bad" lamps the low power ones. Color temperature is the same (--> same wavelengths in my spectra), and is very low so there should not be much blue light. Then what can the trigger of my eyelid twitching and eyestrain and migraines be? I do not see any plausible reason why a small luminous flux triggers symptoms and a larger flux of the same spectrum does not. I can only think that running the tube low power causes more (imperceptible to most) flickering.

                Any thought is greatly appreciated!

                • KM replied to this.
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                    AGI Did you measure the flicker yet, to see if there's a difference between the lamps?

                    • AGI replied to this.

                        KM No, I have not been able to but it is on my agenda (if I find the right equipment).
                        I really want to understand what I am sensitive to, besides the short-term goal of putting an end to this suffering.

                        From the last email I received, it seems the tube can be changed but the new type will still run at low power, so I assume there are not two sub-types of tube for each color temperature, but one type which can be run two ways. In the office though, only the low power mode appears possible. I guess it depends on the circuitry?

                        Another thing I was written, which is unclear to me, is

                        The power voltage for those lights is 100V and the frequency is all 60MHz.

                        60MHz? What is that frequency? How does the flicker frequency relate to it?

                        • KM replied to this.
                            a month later

                            KM Did you measure the flicker yet, to see if there's a difference between the lamps?

                            I am not sure I did things right, and I had to return the equipment so I have not been able to compare "good" and "bad" lamps yet, but here is a preliminary measurement of the flicker of a "bad" fluorescent light.
                            100 KHz....sounds high to be sensitive to, does not it?

                              5 months later

                              On my request, I got the fluorescent bulb closest to my desk changed from 3000 to 5000 K. At the moment of the swap, eyelid twitching was bothering me little and seldom, not sure if my eyes had adjusted a bit to the light or if other co-factors played a role, like diet or slightly better sleep. Note, I still badly suffered from eyestrain and poor concentration / performance.
                              At the change of the bulb, I found using my MacBook Air and my iMac was a bit more pleasant, however, at the same time I felt my eyes got more fatigued (I know it sounds a contradiction, but that is how I felt). Well, after three days under the new bulb, eyelid twitching returned, and way stronger. The weird thing is that it now affects almost exclusively the right eye, whereas earlier only the left eyelid twitched! At times it is so persistent, that I can not even work. I sometimes have twitching also outside the office, especially when I change my direction of view and when I am talking to people. But it gets really intense when I sit under the bulb. I wish I had some kind of meter to prove that. The onset of the twitching clearly coincided with the change of the bulb, apart from an incubation time of 2-3 days.

                              I was not expecting much from a change of the color of the light to be honest. I remind you that the same 3000 K bulbs are okay in the neighboring labs, where they run at higher power (I have not tested a 5000 K bulb at high power). So for some reason lower power makes the lamp bad for my eyes, whatever the color temperature.

                                AGI Eyelid twitching is a psychological stress reaction.

                                • AGI replied to this.

                                    Does the light make your eyes irritated and then the feeling stays for hours? Happens to me. Happened an hour ago with my backyard lights. Just a few seconds of exposure and my eyes and surrounding face muscles (cheeks) feel like they've been through a marathon, which can persist for hours.

                                    • AGI replied to this.

                                      KM Yes, it is similar to when I look at a bad device. Short exposure causes damage, and the damage does not fade quickly upon removing the trigger.
                                      I do indeed feel enormous tension in my face muscles. I never experienced this before, it had always been more of a neck and back of the head tension, accompanied by eyestrain. In the past though I was always able to dodge bad devices and I was never subjected to such discomforting lighting conditions for long. My twitching did not start immediately. It took about 8-9 months. Initially I only suffered from eyestrain and poor performance at the computer and also reading on paper. You may also remember the story with my Samsung Galaxy on5. I now have doubts that the phone became "bad". It may be that I have subjected myself to unbearable conditions for too long (lighting and two Macs), and at a certain point my body started sending out warnings like twitching and photosensitivity.

                                      Sunspark Eyelid twitching is a psychological stress reaction.

                                      I tend to exclude pure psychological effects, if what you mean is that for instance I am stressed out at work and / or do not like my work environment etc. etc. It is not really the case. I am surviving right because I do not have much pressure. But I am unhappy and worried about my state, so that could psychologically influence.
                                      I am more inclined to think that I have been killing myself for nearly 2 years under horrible conditions, and my body is worn out. I think eye and face muscles are similar to other muscles. If you over-stimulate them and if they are not fit (I do not exclude I have some underlying eye condition like heterophoria), they will let you know sooner or later.

                                      @KM Have you explored the psychosomatic avenue?

                                      Partial good news of the last < 24 hours. There has been a rotation of people and a row of LED spotlights which we used to keep off has now been turned on by the newcomer. I freaked out but interestingly working at the desk feels a bit more pleasant. I hope I can confirm. And if it is the case I will try to run some tests and dig out light specs.

                                      • KM replied to this.
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                                            AGI Have you explored the psychosomatic avenue?

                                            No, not yet. I still refuse to believe in this. The symptoms are 100% reproducible, with different results for different lights. There must be a medical explanation other than "it's all in your head". Plus I suffer from PWM, driver eye strain, pretty much all the main problems that have been discussed here. So we all have similar symptoms and the reason for that cannot possibly be we all had the very same psychosomatic problem. Makes no sense, doesn't seem likely at all.

                                              From my perspective it seems there is a disagreement of our brain to the displays / light we look at. The stimulus (light/display) creates a specific response which may be similar to the stress response, but it is the device or light that creates this.
                                              After some years of training in somatics i can quickly reverse any of the symptoms i get from any device, however this cannot be a permanent solution to engage every 20 mins in 10 mins of release activities to reduce the tension in my body.
                                              So for me this is definitely a tech issue and there is a very clear and distinct stimulus. The new displays/lights create all kinds of tensions in the head and upper body starting with the eyes. Also the eyes initiate and control most motor behavior so it is normal for tension to appear in various forms in the head and upper body (eg headaches, neck/jaw, etc).

                                                Peter After some years of training in somatics i can quickly reverse any of the symptoms i get from any device

                                                Interesting. I know nothing of somatics. Is it some kind of exercise involving controlled breathing?
                                                Do you suffer from instantaneous severe symptoms in front of "bad" devices?
                                                Do you mean that, if you did not have to use the bad device anymore, after practicing some exercises for a few minutes you would be fine and free from symptoms for the rest of the day?

                                                    AGI Somatics is the genre for some body training methods like the Alexander Technique, Feldenkrais, Pilates, etc. Personally I am studying the Alexander Technique for about 5 years due to a back problem.

                                                    I can actually get back to almost symptoms-free in less than 30 mins. After two or three hours i am like i never used the bad device. And yes i do get instantaneous severe symptoms if i use a bad device.
                                                    However learning any somatics techniques takes time.

                                                    My Alexander teacher believes that if my eyes become more flexible in their movement i will be able to adapt. We are working specifically on this for a couple of months now, however i still cant say i have seen significant progress but i know it takes time to alter long standing muscular habits.

                                                    • AGI replied to this.
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                                                        Peter i know it takes time to alter long standing muscular habits.

                                                        Thanks for sharing.
                                                        So it has to do with muscles. It is not a psychological issue, at least in the first place. That was my thought too, without being an expert in the field.

                                                          3 months later

                                                          Seagull Probably comes down to how they are powered. If the LEDs are powered by a standard light bulb fitting that will take any type of bulb they will flicker. But, if they are driven by some purpose built LED power supply, with a proper AC-DC rectifier, they will not flicker.

                                                          Moved from My treatment progress and search for solutions

                                                          Interesting! Would that apply to fluorescent bulbs as well? Summarizing the thread I had opened and forgetting for a moment about the LEDs, I got rooms with fluorescent bulbs run at low power which drive me insane and other rooms where the same model of bulbs are run at higher power and give me no issues. I was changed the bulb color temperature in the office but the power could not be varied, and I still have fatigue and eyestrain / eye twitching. So it does not seem to be color temperature related.

                                                              dev