20-20-20 eye break reminder
Every 20 minutes at a screen, look at something about 6 metres away for 20 seconds. Press Start and this page reminds you.
The reminder works only while this page is open. It can be in another tab, but closing the page or the browser stops it. Phones and browsers may delay it a little when the page is in the background.
Runs on your device. Nothing is uploaded. Only today's number of breaks is kept, on this device.
Why 20-20-20?
Long screen sessions can bring digital eye strain: tired or sore eyes, headaches, blurred vision, dry eyes, and a stiff neck and shoulders. The American Academy of Ophthalmology says eye strain does not injure the eye or cause permanent damage.
Focusing up close keeps the eye's focusing muscles working. Looking at something at least 20 feet (about 6 metres) away for at least 20 seconds lets them relax. A window, the end of a corridor or the far wall all work.
People normally blink about 15 times a minute but only about 5 to 7 times a minute at a screen, so eyes dry out. Blink fully a few times during each break.
Sit about an arm's length from the screen, with it a little below eye level, and cut glare from windows and lamps. If your eyes still bother you, see an eye doctor: you may need glasses for screen work.
Sources: American Academy of Ophthalmology, "Eye strain: how to prevent tired eyes" (aao.org: every 20 minutes, look at an object at least 20 feet away for at least 20 seconds; eye strain does not injure the eye or cause permanent damage) and "Computers, digital devices and eye strain" (aao.org: about 15 blinks a minute normally, about 5 to 7 at screens; sit about 25 inches, or an arm's length, from the screen). American Optometric Association, "Computer vision syndrome (digital eye strain)" (aoa.org: the 20-20-20 rule and the common symptoms). 20 feet is 6.1 metres. This is a reminder tool, not medical advice. See an eye doctor about pain, lasting blurred vision or headaches.