Science

Why do we blink?

Ten percent of your waking life is spent with your eyes shut. That sounds odd, but the average person blinks about 12 times per minute, 10,000 times per day, and 4.2 million times per year. That’s a lot of blinking! So, if 10% of your life is spent blinking, and 30% is spent asleep, that means that you spend 40% of your entire life with your eyes closed!

With all the blinking that we do in our lives, it must serve some incredible purpose, right? Aside from taking mental pictures, here are a few of the reasons why it is mandatory to close your eyes every few seconds.

To lubricate our eyes

Close up photo of a human eye
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Of course, the most obvious reason that we blink is to lubricate our eyes. Ever stayed up late watching TV because the last episode ended on a cliffhanger and you just can’t stop? It has been proven that while we are staring at a screen, we blink less. With the lack of blinking over the extended period of time watching the show, your eyes will probably dry out and start to sting.

Lubricating tears are constantly being produced in your body and are made up of three layers: the mucous layer so that it sticks to your eye; the aqueous layer, which is a thick layer that hydrates and keeps bacteria away; and the oily layer, which prevents the other two layers, which are predominantly water, from evaporating. Every time you blink, these tears are pulled across the surface of your eye to keep it lubricated and prevent the spread of bacteria.

To clean our eyes

Photo of a man rubbing his eyes
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Ever had your eyes start to water followed by lots of blinking while sitting around the campfire or while you’re rummaging around in a dusty attic? That’s because dust and particles are continuously getting into your eyes. The watering and blinking are the same as when you use the windshield washer fluid in your car when the windshield gets dirty. The watering is the extra fluid to cleanse and soak up the debris while the blinking is the windshield wiper to wipe it away.

Though it may seem like a pretty standard and involuntary process, strangely enough, there is a wrong way to blink. To blink properly can take training and practice, especially for people with keratoconus or if you are one of the millions of people who wear contact lenses.

To protect against perceived dangers

Photo of a volleyball on the beach kicking up sand
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Imagine sitting at the beach, minding your own business, when the rowdy kid on the blanket next to you throws up a handful of sand that comes right towards your face. Your first instinct, without even thinking, is to close your eyes and brace for impact. Sometimes, this reflex seems to border on precognition because it is so fast.

Your eyes can close in 0.1 seconds when stimulus is detected. Sometimes the stimulus is the bright bathroom light at 3 a.m. Sometimes it’s a fistful of sand. This is called the corneal reflex, and it is designed to prevent as much debris as possible from entering and damaging your eye.

To take a mental break

Photo of a woman with her eyes closed and her hands on her face
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This is an interesting theory that is still being studied today. Researchers found that we blink much more frequently than we need just to clean and lubricate our eyes. This led them to believe that there is yet another reason for blinking. So they got a bunch of volunteers, put them in an MRI, and showed them a movie or got them to read a magazine. What they found is that people blink at perceived break points. In a movie it might be a camera change, and, when reading a magazine, blinking usually occurred at sentence breaks.

The interesting part of this study is that brain activity changed in the fraction of a second it took participants to blink. Brain scans showed that during a blink, mental activity spiked in areas of the brain that operate when the mind is in a state of mental rest rather than focusing on the outside world. Blinking may actually serve as a quick moment of mental rest at microscopic natural pauses in life.

Cover image credit: EHStock / iStock