The 20-20-20 rule: what it is, what the evidence says, and how to actually stick to it

What is the 20-20-20 rule?

The rule fits in one sentence: every 20 minutes, look at something at least 20 feet away for at least 20 seconds.

The American Academy of Ophthalmology (AAO) calls regular breaks using this rule the best way to protect your eyes against eye strain in its guidance on blue light and screens. The American Optometric Association (AOA) gives the same advice on its computer vision syndrome page.

A few details matter:

• 20 feet is about 6 meters. Researchers who have tested the rule describe the distance as 20 feet (6 m). Farther is fine.
• "At least" is part of the rule. Twenty seconds and twenty feet are minimums, not exact targets.
• It is a break for your eyes, not a break from work. You can keep thinking about your task. You just stop focusing up close for a moment.

The AOA pairs the rule with a longer break: rest your eyes for 15 minutes after two hours of continuous computer use. Short and long breaks are meant to work together.

Where the 20-20-20 rule comes from

The rule did not come out of a clinical trial. It came from an optometrist trying to give the public a simple, memorable tip.

In a 2023 Optometry Times article, optometrist Jeffrey Anshel describes how he created it. While working in visual ergonomics, he came across carpal tunnel research suggesting that shorter, more frequent breaks from computer work beat one break every two hours. He reasoned the same likely held for the eyes and boiled it down to "every 20 minutes, take 20 seconds and look 20 feet away."

Two points from his account are worth knowing:

1. It was designed for eye strain. Anshel writes that he created it to relieve eye strain, not as a myopia (nearsightedness) control technique, and he notes his concern at seeing it promoted for myopia.
2. The numbers were chosen to be memorable. That does not make them wrong, but it explains why researchers have since asked whether "20, 20 and 20" are the right values.

Why looking far away is supposed to help

Two things happen when you stare at a screen for a long stretch.

Your eyes hold a near focus. To see something close, the focusing muscles inside your eyes keep working and your eyes turn slightly inward. Looking at something far away lets that system relax. The AOA explains that symptoms usually appear when the visual demands of a task outstrip what your eyes can comfortably keep up with.

You blink less, and less completely. The AAO says people normally blink about 15 times a minute but only about 5 to 7 times a minute while using screens. The research is more nuanced than that headline: a 2014 study that compared reading the same text on a screen and on paper found similar blink rates in both, and the authors suggested that concentration, not the screen itself, drives the drop. Another study linked eye strain symptoms to incomplete blinks, where the lids don't fully close.

Either way, a regular pause breaks up long periods of intense, low-blink focus. That is the logic behind the rule. Whether it works as well as the logic suggests is a separate question.

Does the 20-20-20 rule work? What the evidence says

Honest answer: it is widely recommended, plausible and harmless, but the direct evidence is limited and mixed.

Researchers have pointed this out themselves. A 2023 paper in Optometry and Vision Science noted that "there is relatively little peer-reviewed evidence to support this rule." Here are the main studies that have tested it or something close to it:

What this adds up to:

• The studies are small and short. None followed people for months.
• Results point in different directions. Two studies favor breaks; one found 20-second breaks did nothing measurable in a 40-minute task.
• Symptoms improved more than physical signs. In the most realistic study, people felt better, but tear film tests did not change.
• The effect seems to need ongoing reminders. When the reminders stopped, so did the benefit.

Broader reviews say much the same. A 2018 review in BMJ Open Ophthalmology lists regular screen breaks among the management approaches for digital eye strain, alongside correcting vision and managing dry eye. An earlier review concluded that the efficacy of proposed treatments for computer vision syndrome was "unproven".

So the fair position is this: the 20-20-20 rule is a sensible, free habit backed by major eye care organizations. It is not a proven therapy, and it is not a substitute for an eye exam if you have ongoing symptoms.

How to do the 20-20-20 rule

1. Set a trigger for every 20 minutes. A timer, an app, or a natural break point in your work. Relying on memory alone rarely works (more on that below).
2. Pick a far target in advance. A window, the far end of the room, a doorway down the hall. It should be at least 20 feet (about 6 m) away. Choosing it ahead of time saves you from glancing around and settling on the nearest wall.
3. Look at it for at least 20 seconds. Count slowly, or take about three or four relaxed breaths. Let the target come into clear focus.
4. Blink fully a few times. Close your eyes gently all the way, then open. This is a good moment to undo the half-blinks that creep in during focused work.
5. Go back to work. That's it. No need to stand up for a 20-second break, although you can.
6. Take a longer break every couple of hours. The AOA suggests 15 minutes after two hours of continuous screen use. Do something that doesn't involve close focus: a walk, a phone call, getting water.

Picking a good far target

OSHA's workstation guidance gives a practical example: rest your eyes by focusing on "a clock on a wall 20 feet away."

Why people forget to take eye breaks

Almost everyone who tries the rule finds the same thing: it is easy to understand and hard to do. A few reasons:

• Focus hides the clock. The moments when your eyes most need a break are the ones when you are most absorbed. Twenty minutes of deep work feels like five.
• Breaks feel unproductive. Even 20 seconds can feel like a cost when you're in the middle of something.
• Reminders get dismissed. A pop-up that appears mid-sentence gets clicked away without a glance up. After a few days, many people stop seeing it at all.
• Bad timing. A reminder during a video call or a presentation is useless, and it trains you to ignore the next one.
• No feedback. Skipping one break has no immediate consequence, so the habit never gets reinforced.

The 2023 reminder study above makes this concrete: symptoms improved while reminders were running, then the benefit disappeared a week after they stopped.

Practical ways to stick to the 20-20-20 rule

Choose a reminder method

On a Mac, a dedicated menu-bar app is the least effort. EyeNap, for example, reminds you to do the 20-20-20 look-away and holds reminders during calls, full-screen apps and when you're away from the keyboard, so you aren't trained to ignore them. You can see how it works on the features overview. Any method you will actually follow is better than a perfect one you won't.

Stack it onto habits you already have

Habit stacking means attaching a new behavior to an existing one: "after I send an email, I look out the window." Some natural anchors:

• After you hit send on an email or message
• After every commit, save or export
• While a file uploads, a build runs or a page loads
• Every time you take a sip of water
• At the start of every meeting, before you join

Research on habit formation suggests patience. In a well-known study by Lally and colleagues, summarized by the British Psychological Society, it took participants an average of 66 days for a daily behavior to become automatic, with a huge range from 18 days to a predicted 254. The encouraging part: missing a single day had little effect on the long-term result. Don't quit the habit because you skipped a few breaks.

Make the far view easy

Move your desk so a window or long view is within a glance. If that isn't possible, leave a door open. The less effort the break takes, the more often you'll do it.

Common 20-20-20 mistakes

1. Looking at your phone. It's closer than your screen. You've given your eyes more near work, not less.
2. Looking at a nearby wall. If the wall is 8 feet away, your eyes are still focusing fairly close.
3. Cutting it to five seconds. A quick glance is better than nothing, but give your eyes time to actually relax focus.
4. Staring without blinking. Use the pause to do a few full, gentle blinks.
5. Relying on the rule alone. Breaks can't make up for a screen that's too close, too bright, or a glasses prescription that's out of date. Our guide to digital eye strain covers screen setup in detail.
6. Skipping longer breaks. Twenty-second pauses don't replace getting up and away from the screen every couple of hours.
7. Treating it as a treatment. If symptoms persist despite good habits, that's a reason to get your eyes examined, not to try harder at the rule.

If you'd like something more active to do during longer breaks, see these eye exercises for computer users, along with an honest look at what they can and can't do.

Who should pay extra attention to breaks

• Contact lens wearers. The AAO notes that people who wear contacts and use screens for long periods may find dry eye an ongoing problem, and suggests switching to glasses sometimes to give your eyes a break.
• People who work long, unbroken stretches. The AOA says people at greatest risk of digital eye strain are those who spend two or more continuous hours at a screen every day.
• Anyone over about 40. Age-related focusing changes (presbyopia) make close work harder, and the AOA lists it among the factors that contribute to symptoms.
• Kids. The AAO says the recommendation for children using screens all day is the same as for adults: take breaks.

When to see an eye doctor

Screen-related eye strain is usually temporary. The AAO says eye strain does not cause lasting damage, and if it continues after you've adjusted your workspace, an ophthalmologist can check for dry eye, examine your eye muscles and see whether you need a new prescription. The AOA suggests computer users get a thorough eye exam every year.

Book an appointment if:

• Symptoms are new, or getting worse even after you've improved your habits (Cleveland Clinic)
• Your eyes are consistently red, blurry or watery, or become sensitive to light or painful (AAO)
• Your vision stays blurry at a distance even after you've stopped screen work (the AOA notes this can happen in some people)

See an ophthalmologist right away if you notice any of the signs the AAO lists as urgent:

• Decreased vision, even if temporary
• Double vision
• Pain in the eye
• A dark curtain or veil blocking your vision, or loss of side vision
• Unusual or persistent redness, or excess tearing
• A lot of new floaters or flashes, or a shadow in your side vision

Those are not signs of ordinary eye strain, and no break routine will fix them.