- Edited
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.