No, this is not a flamebait, hear me out.
Since I got the iPhone X I have noticed that when I would watch movies in bed at night, I would wake up with sore eyes that would eventually turn into headaches.
Searching the web I found a lot of people complaining about the PWM on the iPhone X, and I got convinced that it was the screen that was causing my eye strain, so stopped using the X.
Until I got the XR a few days ago. As usual I watched some Netflix while in bed before falling asleep and woke up with the all so familiar sore eyes. This meant that all this time it was not the OLED the one responsible for my headaches, but something else. The only other think that was new both in X and XR was the FaceID.
I started thinking how can it cause problems and came with the theory below. When I am at bed the room is really dark and so I set the brightness level on my iPhone to the lowest setting. My eye-pupils are fully dilated to adjust to the lack of light. My theory is that the FaceID illuminator doesn't take into consideration the amount of light in the environment and uses the same intensity as if it was daylight.
To prove this I took a recording of my iPhone X in similar environment with an IR camera: https://youtu.be/7ewR9wUjnsc
If this wasn't IR but visible light it would be like the iPhone's camera flash going on every 5 seconds right in front of my eyes. There is no question that this would justify the morning soreness and headaches.
My question is: Does the IR light emitted by the iPhone "flood illuminator" have the same effect to my retina even thought I don't perceive it?
Yeah, but that's because your eyelids would be twitching and your temporal muscles contracting in response to to flash. When it's IR you can't see it so your body doesn't do anything in response.
IR light is, in general, very low-energy. Individual photons don't carry enough energy to disturb chemical bonds. The "flash" you're seeing there is less bright than a candle. The flickering not bright at all it's just that CCDs are very good at picking IR light up.
No part of your body can sense or respond to this and even if they did it wouldn't cause soreness.
The IR "flash" you filmed with your phone is about as bright as a television remote control. It's literally impossible that this is causing headaches.
Your headaches come from looking at an illuminated object in a darkish room that's only a few feet from your eyes. Screens in the dark cause eyestrain.
The darker an environment is the more open your pupil is. This reduces the pin-hole focusing effect of the pupil and requires that the lens of the eye be more carefully focused to see. Focusing that tightly is difficult because the lens muscles have to stay in one level of contraction for a long time.
Your body instinctively tries to squint so that the eyelids being close together and the eyelashes will cause a pinhole effect that will help you see. The fight between squinting for focus and opening your eyelids to make things less dark makes your head sore and causes tension headaches. This effect becomes more pronounced with age.
The first thing you said about PWM? That's a thing people say when they're not doing so well with cause and effect and cognitive bias. This new thing you're inventing about the IR is a much worse version of that.
It doesn't have a damn thing to do with the manufacture or components of your phone. Stop trying to read a phone screen (or look at anything on a phone close up) in a dark room. That's it. Don't do that. It's a thing that makes your eyes and head sore. It's really well documented. No new explanation is needed.