What can my blinking tell me about my health?

Dr. Trisha Pasricha. PHOTO: health.harvard.edu

Q: I feel like I’m blinking more often than usual. What can blinking tell me about my health? And why do we blink?

A: We blink about once every three to five seconds and usually don’t even realize it’s happening, despite losing an incredible amount of our daily visual input to blinking – up to 10 percent.

Blinking serves several practical purposes: It wets and cleans the surface of the cornea and can reflexively protect the eye from rapidly approaching objects. But that’s not quite the end of the story.

In some cases, a change in blinking might herald a health problem. Here are some reasons blinking may change that can tell you something about your health:

Slow or infrequent blinking: Decreased blinking can be one of the early signs of Parkinson’s disease. One important neurotransmitter influencing our ability to pay attention and show flexibility is dopamine. Several studies have found that the rate at which we spontaneously blink mirrors the neurotransmitter’s activity in our brains – the lower the dopamine, the more we fixate on one subject, and the less frequently we blink. And the hallmark of Parkinson’s is the loss of dopamine-producing nerve cells.

Patients with the autoimmune condition Graves’ disease also experience changes to their blinking pattern, which may be related to cornea damage. And other neurological conditions besides Parkinson’s, such as stroke, can slow the normal blinking rate. Slower blinking has also been associated with head injury among athletes.

Excessive blinking: Increased blinking can be a sign of sleepiness while trying to perform a demanding task such as driving while drowsy (if you notice this happening, keep everyone on the road safe and get some rest before continuing your journey). People who are suffering from pain or experiencing very bright lights also blink more frequently.

Excessive blinking can occur when your body tries to compensate for dry eye disease, which occurs for a number of reasons, including Sjogren’s syndrome or side effects from certain medications like antihistamines.

Dry eye disease is also incredibly common among frequent screen-users. We blink less frequently when we stare at our screens.

If you plan on spending hours in front of your computer, set 20-minute timers to step away for a minute or two from your screen. I also like the concept of “blind working” – closing your eyes for brief, deliberate breaks in your workday when you actually don’t need to have them open, such as during a telephone call or while waiting for a program to load. Heightened screen time may also be associated with damage to the glands that keep our eyes healthy as well as myopia.

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Why do we blink?

In many situations, people blink in unexpected patterns that don’t seem to have anything to do with maintaining their eyes’ moisture.

In the 1920s, scientists studying this phenomenon wondered: If blinking was not simply there to dust off the corneas, what did it really mean?

Some of their observations made intuitive sense – they noted that people blink more frequently while smoking; smoke is a known corneal irritant. But they also found people blinked less frequently while reading than they did while talking, when the environment was otherwise the same – and oddly, that people reading almost always blinked at punctuation marks instead of text.

Other findings were just as puzzling. Unexpected sounds, even if not loud, caused children to blink. And people blinked more frequently when they became angry or anxious.

Decades of research has revealed that blinking is much more than the windshield wiper of the body but rather a window into the state of our minds – how carefully our attention is focused and whether we’re ready for new stimuli.

Studies have shown that increased spontaneous blinking can be a sign of gathering new information – especially when it challenges the “rules” of a known environment. For instance, babies in bilingual households blink more rapidly as they switch between hearing different languages spoken, which correlates to signaling in areas of the brain governed by dopamine. And people blink in synchrony when watching the same movie – researchers have found that we tend to stare continuously while the action of the main character unfolds, but we all start to blink unconsciously during the same implicit narrative breaks – such as when there’s a shot with no humans in the scene.

In a similar way, blinking plays a role in our social communication. Scientists have measured that when two people are communicating smoothly with each other and holding the other’s interest, their blinking patterns start to align.

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How did humans evolve to blink?

Scientists believe blinking developed several times across evolutionary history – and in some cases, like with snakes, became lost again. A study of mudskippers published last year in the Proceedings of the National Academy of Sciences hypothesized that it was the transition from aquatic life to land that made blinking beneficial to survival – even for our own ancestors, who also emerged from the sea several hundred million years ago.

One reason blinking on land is critical is because the corneas of our eyes don’t have blood vessels and so they derive oxygen by diffusion from the environment surrounding them. Oxygen diffuses more easily across wet surfaces, and spontaneous blinking helps maintain a thin, fluid film layer on our eyes. Another reason is that dangerous objects travel much more quickly through thin air than they would through water – so blinking reflexively to shield the eyes from injury is significantly more important on land.

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What I want my patients to know

People often buy laptop raisers or elevate their screens to eye level. Instead, try placing the screen at a 10-degree downward gaze angle (and ideally two to three feet away from you). Doing so may relax the muscles around your eye to help you blink more completely, and it can reduce tear evaporation.




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