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The 20-20-20 rule for eye strain: what it is and what the evidence says

What the 20-20-20 rule is, what studies actually show about it, the other eye-care habits ophthalmologists recommend for screen work, and how to get gentle reminders in Chrome without breaking your focus.

Updated · 3 min read

The 20-20-20 rule is the most repeated piece of advice about screens: every 20 minutes, look 20 feet away for 20 seconds. It’s simple, it’s free, and it’s recommended by eye doctors. It’s also less proven than most people assume. Here’s what we know, and what else helps.

In short

  • Screen strain comes from close focus and blinking less, not from blue light.
  • The 20-20-20 rule is recommended by ophthalmologists; the research behind it is small and mixed.
  • Distance, glare and blinking matter as much as breaks.

Why screens tire your eyes

Looking at something close keeps the focusing muscles inside the eye contracted. Looking far away lets them relax. At the same time, people blink much less while concentrating on a screen: the normal rate of around 15 blinks a minute can fall by a third to a half. Fewer blinks means a drier, grittier surface by the end of the day. Neither problem is caused by the screen’s light itself.

What the evidence says

  • Recommended: the American Academy of Ophthalmology and the American Optometric Association both advise the 20-20-20 rule.
  • Some support: a small 2022 study with 29 people found dryness, sensitivity and discomfort fell noticeably after two weeks of 20-20-20 reminders.
  • Some doubt: a small 2020 study found no change in eye-strain symptoms after twenty days, and reviews note that little research has tested the rule directly (Medical News Today).

The fair reading: it’s unlikely to hurt, it may help, and the habit of looking up from the screen is worth having anyway.

Other habits that help

HabitWhy
Screen about an arm’s length away (around 25 inches)Less effort to focus
Top of the screen at or just below eye levelEyes look slightly down, less of the eye surface is exposed
Cut glare with a matte screen or by moving lampsLess squinting
Blink fully, use lubricating drops if dryKeeps the surface moist
Match screen brightness to the roomA bright screen in a dark room is hard on the eyes

If strain persists, see an optometrist. Uncorrected or outdated glasses are a common cause.

Reminders that don’t wreck your focus

The problem with a reminder every 20 minutes is that it interrupts good work. In Pax, Settings › Wellbeing has three separate reminders, each with its own interval: Rest your eyes, Drink water and Stand up and stretch.

  • Water and stretch reminders are skipped during focus sessions; only the 20-second eye break comes.
  • Only during work hours keeps evenings and weekends quiet.
  • They arrive as gentle notifications, even with no tab open.

Questions people ask

What is the 20-20-20 rule?

Every 20 minutes, look at something about 20 feet (6 metres) away for at least 20 seconds. The American Academy of Ophthalmology and the American Optometric Association both recommend it for digital eye strain.

Does the 20-20-20 rule work?

The evidence is thin and mixed. A small 2022 study found dryness and discomfort fell after two weeks of reminders; a small 2020 study found no change. It’s low cost and low risk, so most eye doctors still suggest it.

Why do screens strain the eyes?

Close focus keeps the eye’s focusing muscles working without rest, and people blink far less at screens, by a third to a half, so the eyes dry out.

Does blue light from screens damage the eyes?

The American Academy of Ophthalmology says blue light from computers has not been shown to increase the risk of eye disease. Strain comes from focus and blinking, not the colour of the light.

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