Right now, while you’re reading this, your eyelids are sweeping closed and open every few seconds without you noticing. People blink about 15 to 20 times a minute on average. Each blink lasts about 300 milliseconds - a tenth of a second - but multiply that by all day, and your eyes are actually closed for roughly 10% of your total waking hours.
Blinking does several jobs at once. It spreads a thin layer of tears across your eye to keep it moist. It clears tiny bits of dust. And it gives your overworked photoreceptor cells a tiny rest. You can’t see during a blink, but your brain has gotten so good at editing out those dark gaps that the world looks completely continuous to you.
Interestingly, you blink less when you’re focused on something - like a screen, a book, or a video game. This is one reason your eyes feel tired and dry after long sessions: you’ve stopped giving them the constant blink-bath they normally get. Doctors recommend looking away and blinking deliberately every 20 minutes to help.
