Blue
light blocker.
I use "iris mini" for my mac, "flux" for my work laptop, and the built-in "night shift" on my iPhone.
It takes getting used to the orange-ish glow instead of the blue/white glow, but once you get used to it you'll be having to put on sunglasses when you look at a friend's screen and won't understand how they can stand it!
That or get yourself a pair of something like
these.
This gets into a whole can of worms about blue
light doing a heck of a lot more to you than just hurting your eyes but that's for another thread...