Does the 20-20-20 rule work? A small study put it to the test

The 20-20-20 rule is simple: every 20 minutes, look at something 20 feet (about 6 metres) away for 20 seconds. It's widely recommended to people who spend long hours at screens. What's surprising is how little it had been directly tested, until a small study in 2023.

The study

Researchers recruited 29 computer users who already had symptoms of digital eye strain (Talens-Estarelles et al., 2023). For two weeks, software on their computers reminded them to follow the rule. Then the reminders stopped for a week. The team measured eye strain and dry eye symptoms with questionnaires, and also measured the eyes themselves: the tear film, the surface of the eye, and how well the two eyes worked together.

While the reminders were running, participants took more breaks, and their eye strain and dry eye symptoms went down. One week after the reminders stopped, the improvement was gone.

The objective measurements didn't change: not the tear film, not the eye's surface. People felt better, but their eyes didn't measurably change in two weeks.

What it tells us, and what it doesn't

This is a small study with no control group, over a short period. Without a control group, some of the improvement could come from simply paying more attention to your eyes. So it's a promising early result rather than proof.

It doesn't show that breaks treat dry eye or improve vision, and it isn't a reason to skip an eye test. If your eyes are persistently sore or dry, or your vision has changed, see an optometrist or doctor.

The part about reminders

The most interesting result for anyone trying to build a habit is the last one. Symptoms improved while reminders ran and came back once they stopped. The rule helped, in the sense that people felt better, only as long as something prompted them to follow it.

That matches research on sitting. A 2017 review of 17 trials looked at apps, prompting software and wearables designed to reduce sitting (Stephenson et al., 2017). On average they cut sitting by about 40 minutes a day in the short term. Beyond six months, the effect had nearly vanished.

Reminders work while they're working. The lesson isn't that reminders are pointless. It's that the behaviour tends to lapse without them, so a reminder you're happy to keep getting beats one you'll mute in a week.

Why the numbers are 20, 20 and 20

The rule's appeal is that it's easy to remember, not that each number was worked out precisely. The 2023 study tested the rule as usually stated, so that's what we know about. Nobody has shown that 25 minutes, 15 feet or 30 seconds would be better or worse.

In a real office, 20 feet is roughly the far side of a room, the end of a corridor, or anything outside a window. If you can't see that far from your desk, looking as far away as you can is a sensible approximation, and a short walk gets you the distance view for free.

How to use the rule

• Every 20 minutes or so, look at something far away: out of a window, down a corridor. Around 6 metres is enough.
• Hold it for about 20 seconds, and let yourself blink.
• Use a reminder. The study suggests the rule helps while you're prompted to follow it.
• Pair it with a movement break when you can. Standing up and walking away from the screen changes where you're looking anyway.

DeskBreak's 1-Minute Eye Break is a guided version: a look into the distance, a few slow blinks, and a moment away from the screen. It's for comfort during screen work, not a treatment for any eye condition.

If you try the rule, give it the same test the researchers did: notice how your eyes feel at the end of the day for a couple of weeks with reminders, then without. It's a small experiment, and yours is the result that counts for you.