The first thing I do in the morning is check my phone. I grab my phone off its charger, silence the alarm, press the power button—and instantly recoil as the screen’s hideously bright light turns my retinas to ash.

Our phones are bright and colorful by design, as they hope to lure us in all day, every day. But I’ve found a way to fight back that’s easier on my rods and cones, and lighter on my batteries. It might even help me use my phone a bit less.

There...