The explanation has always been simple. With every blink, your eyes open and close. By so doing, your eyelids coat the surface of your eyes with tears. And since these tears contain nutrients and self-cleaning properties, they clean and nourish your eyes.
But as it turns out, this simple explanation does not explain everything. It doesn't explain the 15-blinks-per-minute rate. And it doesn't explain the fact that people tend to only blink during momentary rest periods.
According to The Smithsonian, it took an earlier experiment, a couple of inquisitive Japanese scientists, and several sessions with Functional Magnetic Resonance (fMRI) machines to actually crack the code as to why human beings blink so often.
The earlier experiment
The experiment that provided the first piece of the puzzle determined one thing, and that is: there is nothing random when it comes to blinking in humans. That for some reason, blinking seems to occur during given times, which is when a person is in a state of momentary rest – however brief the rest period is.
The researchers observed that people reading magazines often blinked when they reached the end of a sentence. And when the experiment was performed on people watching television, it was found that they often blinked at the end of scenes or when there wasn't really anything happening on screen.
The Japanese researchers and the sessions with the machines
While the findings of the first experiment seemed trivial to some, it didn't for a couple of Japanese researchers. They asked themselves the question "Why" and followed through by doing some experiments of their own.
They decided to use the TV show used in the first experiment, but instead of just observing with their eyes, they decided to use fMRI machines to help them detect the activity of the brain at the exact moment when a person was blinking.
What they found out
By monitoring the brain activity of their subjects, the scientist noticed that there were increased brain activity levels in regions associated with the default network of the brain. In other words, the brains of the subjects tended to switch to rest-mode every time they blinked.
What this means
The findings of the researchers imply that the main reason why you blink so often, may not be because of tear-coating—although this is important. They suggest that blinking is likely to be more of a momentary pose. A thought-gathering brief period of calm that helps you to process visual stimuli. In other words, the main reason why you blink 15 times a minute is because your brain needs those tiny breaks so as to be able to process what you are seeing. Talk to places like Atlantic Ophthalmology for more information about how your eyes work.