By 3 PM every workday, my eyes felt like sandpaper. Headaches behind my right eye, blurred vision when I looked up from my monitor, and the constant urge to rub my eyes — which makes it worse, by the way.

I went to an optometrist expecting to need glasses. He asked about my screen habits, nodded, and said “You have digital eye strain. It is completely reversible and I am going to give you exactly one rule to follow.”

The 20-20-20 rule

Every twenty minutes, look at something at least twenty feet away for twenty seconds. That is it. The rule is simple but the reason matters: your eye muscles are relaxed when looking at distant objects. When you stare at a screen two feet away for hours, those muscles stay contracted the entire time. They fatigue, just like any muscle held in one position too long.

The twenty-second break lets them reset. I set a recurring timer on my phone and on my computer. At first it felt disruptive. By day three it was automatic.

Blink more (seriously)

Humans blink about fifteen times per minute normally. When staring at screens, that drops to five to seven times. Less blinking means your eyes dry out faster. Dry eyes feel gritty and tired — exactly what I was experiencing. Being aware of this is half the fix. I put a sticky note on my monitor that just said “BLINK” for the first week.

Adjust your screen

Your monitor should be at arm’s length and the top of the screen should be at or slightly below eye level. Looking slightly downward is the most comfortable angle for extended viewing. Looking up strains your neck and exposes more of your eye surface to the air, accelerating dryness.

Brightness should match the room. If your screen glows like a window in a dark room, it is too bright. Reduce it until it feels like a piece of paper under the room’s lighting.

Night mode all day

Enable the warm color setting — Night Shift, Night Light, or f.lux — and leave it on during the day, not just at night. Reducing blue light reduces eye fatigue regardless of the time of day. The slightly yellow tint looks odd for about fifteen minutes, then your brain adjusts and you stop noticing it.