iPhones
Most new smartphones use a display technology called OLED. These displays use a technology called PWM (pulse width modulation) for dimming the display. This creates a flicker, which while not perceptible to the eye, can cause all kinds of symptoms -- headaches, nausea, etc. Every time I have tried the newer iPhones with OLED displays in the store, I find I immediately feel eyestrain. This has kept me from buying one of them and I have stuck to an iPhone with the older display technology called LCD.
If you have had issues with newer phones, you might be sensitive as well. This article sums up the problem nicely.
PWM may not be the whole issue. There's also scrolling speeds, addressed to some extent by ProMotion in some newer iPhones, and also temporal dithering. More on temporal dithering below.
MacBooks
With newer MacBooks, a small, but not insignificant, number of users, including myself, have experienced really bad headaches when using them. A few things that I did to try and mitigate the problem included turning off true tone, turning off auto brightness, and turning off dimming when running on battery. None of these helped.
Digging deeper, I discovered that there's a feature called temporal dithering that Apple implements in order to render a larger number of colors than the display is natively capable of. Unfortunately there is no way to turn this off using native controls in macOS.
In some of the forums, it was suggested that SwitchResX is an app that can be used to disable temporal dithering by setting the display to render millions of colors rather than billions of colors which is the default.
Another useful tool for checking various aspects of displays such as pixel inversion is the Lagom LCD monitor test pages. Testing side by side with a Dell XPS, the M1 MacBook Air showed noticeably more flicker.
Finally, Iris is another tool attempts to get around PWM with laptops by using an app to control brightness and filtering colors in a way that makes the display experience easy on the eyes.
References
- Exclusive: Ultra-bright displays are destroying our eyes, but the OnePlus 12 gets it right
- TÜV Rheinland Intelligent Eye Care certification
- Disabling dithering on Apple silicon Macs using Stillcolor.
- Flicker Sense -- Issues with flicker in LED lights and displays and how to report them
