Grayscale on iPhone for health and profit.
tl;dr: Settings --> Accessibility --> Display & Text Size --> Color Filters --> Grayscale
My eyes started to hurt in the evenings a few weeks ago, which makes sense given how much time I spend in front of a big screen for work. I also spend quite a bit of time on my little screen in between the times I am sitting in front of the big screen. I'm working on reducing the amount of time I spend on the little screen (and taking more breaks from the big screen), but for the unavoidable times on the little screen, I've discovered that you can make your display grayscale on iPhones. It's nice! It also has the added benefit of making all the shiny things designed to steal your attention much less shiny.
Here's how to do it:
Settings --> Accessibility --> Display & Text Size --> Color Filters --> Grayscale
One issue I've run into, however, is that it can be a hassle to turn off when I just want to look at something where it's helpful to differentiate colors, like a map of state-by-state Barbie-vs-Oppenheimer search interest that eerily matches the 2020 electoral map.
I turned to my usual solution, Apple Shortcuts. The action you're looking for is "Turn color filters on/off". Unfortunately, I couldn't find an easy way to check the current status of the color filter, so I now have two shortcuts "Colorize Me" and "Grayscale" so that I can switch back and forth as needed (yes, I'm lazy).
On the subject of being nice to our eyes (and many other benefits), for the past week we've also been trying some fairly radical sleep hygeine stuff (in short: sun down, lights out, candles on), which I may write about if we make it to a month.
Update: We did this for about three weeks. It was fantastic. However, we don't have our act together to have every chore done by sundown and doing dishes by candlelight wasn't great.