Why Do We Blink Our Eyes?

Everybody does it without even thinking about it. And it happens so fast that it has spawned a common expression of speed: “It happened in the blink of an eye.” 

Blinking is the semi-autonomic action of rapidly closing your eyelids. It is an essential eye function that spread tears across your eyes and eliminates irritants and foreign objects from the surface of your cornea and conjunctiva. 

It takes a little longer than a blink to explain the science and reasons behind blinking, so bear with us as we answer your questions.

Why We Blink Our Eyes

Blinking lubricates your eyes through corneal irrigation, using your tears and a lubricant secreted by your eyes. You also blink to protect your eyes from irritants and foreign objects.

When you blink, your eyelashes trap most of the foreign objects and potential irritants before they can reach your eyeball. The eyelashes serve as a line of defense against things such as dust particles and other elements.

Because blinking occurs more frequently than necessary to keep your eyes lubricated, researchers believe blinking may have secondary functions. Some researchers suspect that blinking may help you disengage your attention.

Research shows that when you blink, your dorsal network, which is responsible for the voluntary control of your visual perception of spatial relationships of objects, experiences a decrease in cortical activity. At the same time, cortical activity increases in your default-mode network, the brain regions that are active when you are not focused on the outside world.

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How We Blink Our Eyes

Several muscles control the reflexes of blinking. The main muscles responsible for blinking are located in your upper eyelid. These muscles are the levator palpebrae superioris and orbicularis oculi muscles.

The contraction of the levator palpebrae superioris muscle opens your eyelid. The orbicularis oculi closes it. The superior tarsal muscle, or Muller’s muscle, situated in your upper eyelid, and the palpebral muscle located in your lower eyelid function to widen your eyes.

When you blink, all these muscles are involved in the semi-autonomic action. The muscles are also essential for other eye functions, such as winking and squinting.

There are three types of blinking — spontaneous, reflex and voluntary.

• Spontaneous Blinking: It happens without internal effort or external stimuli. This type of blinking happens subconsciously, like breathing or digestion.
• Reflex Blinking: This is a response to external stimuli such as foreign objects appearing close to your eye or in contact with your cornea. It occurs faster than a spontaneous blink.
• Voluntary Blinking:  It is a conscious blink that utilizes all the involved muscles.

Benefits of Blinking

One chief benefit from blinking is that it helps clean the surface of your eyes of any particles or debris. It helps decrease your risk of getting an eye infection significantly and helps lubricate your eyes as it washes your eye surface with fresh tears.

The natural washing helps prevent uncomfortable dry eyes. Also, as you clear the surface of your eyeball when you blink, your vision improves considerably.

Blinking also nourishes your eyes with oxygen and nutrients, thus keeping your eyes healthy. Finally, blinking helps reduce eye fatigue via the reorganization of ocular muscles.

Blinking and Your Brain

While blinking may be a response to external stimuli, the action appears to be controlled in your orbitofrontal cortex, a region in the frontal lobes of your brain.

Dopamine production in your brain is also associated with frequent spontaneous blinking. Conditions such as Parkinson’s disease, where dopamine levels are reduced, result in reduced blinking rates. Conversely, conditions such as Schizophrenia, where dopamine levels are elevated, result in increased blinking rates.

Excessive Blinking

When your blinking reflex is overstimulated, excessive blinking occurs. Some causes are eye irritation, eyestrain, vision problems and neurological conditions. Specifically:

• Eye irritation: Eye irritants such as dust, chemical vapors, pollen, smoke, and foreign objects result in excessive blinking. Other sources of eye irritation include inflammation, dry eyes, ingrown eyelashes, and eye injuries.
• Eyestrain: Eyestrain caused by prolonged focusing can cause excessive blinking. It can be caused by prolonged screen time, prolonged reading, and exposure to bright light.
• Vision problems: Eye conditions such as myopia, hyperopia, and presbyopia can also result in frequent blinking.
• Neurological conditions: Rarely, neurological conditions including Tourette syndrome, multiple sclerosis, and Wilson’s disease may be associated with frequent blinking.

One of the first signs of excessive blinking is blinking more than you want to, which interferes with your vision or daily activities. A human adult blinks approximately 12 times per minute, with a blink lasting about one-third of a second. If your blink rate is significantly higher than this, you may have an excessive blinking reflex.

Excessive blinking can resolve on its own depending on the cause. Treatment options vary based on the causative agents. In the case of eye irritation, avoiding irritants and treating causative conditions are recommended. Eye strain is treated by reducing exposure to factors that cause it. Correcting vision problems may eliminate the associated excessive blinking.

FAQs

What causes us to blink?

External stimuli such as an object appearing in front of your eyes or a foreign object in your eye cause reflexive blinking. Eye strain and dry eyes can also cause you to blink.

What happens if we don’t blink?

The most notable effect of not blinking is dry eyes, which can eventually impact your vision.

Why do we blink without thinking?

Blinking is largely an involuntary reflex. It is controlled by your autonomic nervous system, which acts unconsciously to regulate bodily functions.

References

1. Blink-related momentary activation of the default mode network while viewing videos. (December 2012). Proceedings of the National Academy of Sciences of the United States of America.

2. High-speed camera characterization of voluntary eye blinking kinematics. (August 2013).  The Royal Society Publishing.

3. Functional MRI of Brain Activation by Eye Blinking. (July 1999). Experimental Eye Research.

4. Blink and you miss it! (July 2005). University College London.

5. Eyelid movements. (February 2015). University of Minnesota Medical School.

6. Dopamine and inhibitory action control: evidence from spontaneous eye blink rates. (May 2009). Experimental Brain Research.

7. Excessive Blinking in Children. (January 2022). American Academy of Ophthalmology.

8. Excessive Blinking in Children. (October 2019). American Association for Pediatric Ophthalmology & Strabismus.

9. Don’t Blink and You’ll Miss It. (March 2017). Facial Palsy UK.