Tired, dry or sore eyes after a day at a screen are common, uncomfortable and fixable. The main cause is simple: you blink much less while looking at a screen. Regular breaks for your eyes, a well-placed screen and comfortable lighting deal with most of it. This piece is part of our guide to energy and focus.

Why do screens make your eyes tired?

Mostly because of blinking. The American Academy of Ophthalmology explains that "Humans normally blink about 15 times in one minute", but "we only blink about 5 to 7 times in a minute while using computers and other digital screen devices." Blinking keeps the surface of the eye moist, so fewer blinks mean drier, more irritated eyes.

Holding your focus at the same short distance for long periods adds to it, as can glare, a screen that is too bright or too dim for the room, and glasses or contact lenses with an out-of-date prescription.

What is the 20-20-20 rule?

It is the academy's simplest advice for screen breaks: "Every 20 minutes, shift your eyes to look at an object at least 20 feet away, for at least 20 seconds." Twenty feet is about six meters, roughly the far side of a room or the view out of a window.

It works because it gives your eyes a regular change of focus and a chance to blink normally. Pairing it with a reminder, or with natural pauses such as sending an email, makes it easier to keep up.

How should you set up your screen?

  • Distance: sit "about 25 inches (right about at arm's length) from the screen", the academy suggests.
  • Height: "position the screen so your eye gazes slightly downward, not straight ahead or up."
  • Brightness: "Adjust your screen brightness to match the level of light around you", and try increasing the contrast.
  • Glare: "Try using a matte screen filter to cut glare", and place the screen side-on to windows.

Our article on setting up a workspace for focus covers screen position and lighting in more detail.

Do eye drops help with screen eye strain?

They can. The academy suggests you "Use artificial tears to refresh your eyes when they feel dry", and a humidifier can help in a dry, warm room. If you need drops often, or your eyes stay red or painful, see an eye doctor.

Do blue light glasses prevent eye strain?

The evidence says no. The academy states that "there is no scientific evidence that blue light from digital devices causes damage to your eye", and that "The Academy does not recommend any special blue light-blocking eyewear for computer use." It notes that studies suggest these glasses do not improve the symptoms of digital eye strain.

Glasses made for computer distance are a different thing. The academy points out that "computer glasses for reducing eye strain are not the same as "blue light blocking" glasses". If you wear glasses and your screen distance falls between your reading and distance prescriptions, ask your optician about them.

Screens late at night are a separate issue that affects sleep rather than your eyes. Our article on whether blue light really ruins your sleep covers that.

Can screens damage your eyes permanently?

No. On the belief that long screen use harms the eyes permanently, the academy is direct: "Thankfully, this is not true." Eye strain is uncomfortable and can affect how well you work, but it does not cause lasting damage.

When should you see an eye doctor?

  • Blurred vision, headaches or strain that do not settle with breaks, which can mean you need glasses or a new prescription.
  • Eyes that stay red, painful or very dry.
  • Any sudden change in vision, flashes or floaters, which need prompt attention.

Regular breaks help more than your eyes. Standing up and moving during them is good for the rest of you; see movement snacks for ideas.