Why do we blink?

Dear Alice,

Why do we blink?

Dear Reader,

From a strictly functional perspective, blinking is a way to keep the eyes clean and moist. When the eyelids close over the eyes (as they do about ten to fifteen times per minute, on average), they coat the eyeballs with the following three types of fluids:

  • Tears released by the tear glands in the eyes
  • Lubricating oil produced by sebaceous glands found between each eye lash that keeps tears from evaporating too quickly
  • Mucus that further lubricates the eyes and helps tears adhere to the surface of the eyeballs

These three fluids also help flush out any dirt or other foreign objects that might sneak past the eyelashes. Blinking can also serve as a proactive way of keeping things from entering the eye in the first place, by lowering the eyelids and lashes for protection — this is why people blink when something startles them or moves quickly towards their faces.

Blinking also seems to be tied to concentration and information processing. People who are deeply focused on learning or on a detailed task (e.g., working at a keyboard, sewing intricate needle point, or picking minute bits of lint from their navels) blink much less than those who are not actively engaged. They can become so engrossed in what they are doing that they actually "forget" to blink, causing that gritty, tired eye feeling. This wide-eyed tactic is not really necessary — the muscles that control blinking contract and relax so quickly that blinking does not obstruct vision.

So, if you're prone to dry, scratchy eyes, the next time you're carefully scrutinizing something, don't forget to bat your eyelashes occasionally to make sure your peepers are adequately lubed.

Last updated Jul 28, 2015
Originally published Jul 19, 2002

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