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What Causes Sleep in Your Eyes? 8 Eye-Health Questions

ophthalmologist-glassesFascinating facts about your eyes—straight from the experts.

What causes sleep in your eyes?

Glands in the eyelid and in the protective tissue that covers the eye produce secretions that help protect the eye. These secretions can build up under closed lids because little evaporates or drains into the nose and back of the throat. The residue is colloquially called “sleep.”

The doctor says I have dry eyes even though they water all the time. How can that be?

Dry eyes are an increasing problem in our air-conditioned, airline-traveling, contact-lens-wearing, medicated, laser-corrected, aging society. Too few tears, decreased blinking or tears with abnormal composition result in dry eyes that itch, sting, burn, get red and cause blurred vision.

newsletter-graphicThese problems are all defects involving baseline tears, or the constant tears that moisten the eye’s surface. In response, however, some people secrete reflexive tears in high volume. These are more watery tears meant to wash out the eye, not effectively lubricate it. So they don’t correct the problem; they just give you the seeming conundrum of watery dry eyes.

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Will looking at the sun for just a second really hurt my eyes?

While a quick glance might not cause a problem, looking directly into the sun for any longer can cause irreversible damage.

Staring at a solar eclipse, for example, or accidentally falling asleep in the sun with your eyes partially open can harm the macula—the central part of the retina, located in the back of the eye, which is responsible for the most detailed, central part of vision. This disorder, called solar maculopathy, may result in decreased vision and a central blind spot.

What if the sun is setting and isn’t so bright?
The damage might just take longer.

Because the sun is lower in the horizon, pollutants and the earth’s atmosphere can partially block its rays, making it appear red or orange. But don’t let this change fool you; if you stare directly at it, permanent harm can still occur.

Why do people get double vision but not triple or quadruple vision?

If you look at an apple, though each eye registers it separately, your brain sees only one. But if the eye muscles fail to hold the eyes perfectly in sync, the brain keeps the images separate. You see two apples because you have two eyes.

To view the difference between the two eyes’ images, focus on a finger held out in front of you. Close one eye, then the other, and note the change in the background.

Why do onions make my eyes water?

Whether it’s a stick in the eye, an infection, smoke from the barbeque or a chemical irritant (such as shampoo), anything that irritates the surface of the eye causes tearing.

Crushed or peeled onions release small particles as fumes that irritate the eye. You can think of this reflex tearing as a natural mechanism for the eye to protect itself.

In 2008, researchers announced they genetically engineered an onion that does not produce the enzyme that makes your eyes water. While the new breed may be years away from your supermarket, onion lovers can try peeling under a steady stream of water to wash away the fumes before they reach the eyes.

Why does looking at a computer a long time hurt my eyes?

An improper glasses prescription or poor lighting conditions can result in eyestrain, causing eye pain, headache or blurred vision. Dry eyes are another common problem associated with tedious visual activities (like staring at a computer): as you stare, you blink fewer times per minute than normal, leading to faster evaporation of the natural protective tear film.

To diminish or eliminate eyestrain:

  • Take frequent vision breaks: look away briefly, focus on a distant object and blink several times.
  • Use artificial tears prior to a computer session, and reapply as much as needed.
  • If you need glasses (or don’t know if you need them), make sure your prescription is up-to-date.
  • Get regular eye exams to make sure your symptoms are not a sign of some more serious condition.


newsletter-graphic8. My vision is fine, but I have cataracts. Do I need surgery?
A cataract is a clouding of the natural eye lens caused by aging, medical conditions such as diabetes, or trauma. This can result in blurry or yellowed vision.

If it doesn’t interfere with driving or everyday activities, you may elect to wait to have your cataract removed. But keep your yearly eye appointments, and let your ophthalmologist know of any vision deterioration to make sure it’s cataracts.



Johathan M. Davidorf, M.D., board-certified ophthalmologist; director, Davidorf Eye Group, Los Angeles; assistant clinical professor, UCLA's Jules Stein Eye Institute.

Paul J. Dougherty, M.D., board-certified ophthalologist; medical director, Dougherty Laser Vision, Los Angeles; assistant clinical professor, UCLA's Jules Stein Eye Institute.


Last updated and/or approved: September 2010. Original questions and answers appeared in various issues of the former print magazine. Bios current as of those issues. This general health-care information is not meant as individual advice. Please see our disclaimer.
Comments (4)add comment
written by David Baker , December 01, 2014

All my life I have suffered with sleep in my eyes, they are clear for many hours and then suddenly I get a slight blurr across my vision which is clear sleep thank you
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Highly Sufficient Data! A 10/10
written by Timothy , January 11, 2014

I learned a lot today from reading this article. I must say, I was highly intrigued! Job well done. I am OBSESSED with maintaining healthy vision and as a result I make sure I take care of my eyes. This article only helped to make me even more aware on the do's/don't's of optimal vision. Thanks a bunch and Happy New Year.
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Re: Free Eyecare? please
written by Leigh Ann , July 24, 2013

Hi, Jeff. This resources list from the National Eye Institute might be helpful:

In addition, the nonprofit Modest Needs might be worth looking into:

We hope you find the assistance you need, and we wish you the very best of luck.

Leigh Ann Otte
Managing Editor

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Free Eyecare? please
written by Jeff A , July 24, 2013

Ok I have applied for free healthcare with the state. They refused me said I made to much money. Which I do not my bills equal my income almost exact. I do not have any expenses for luxuries. Cant even save $5 a week have to feed the family. So my question is can I get help anywhere to get my eyes checked and maybe new glasses. The ones I have are held together by tape and blurry for my vision. Worse without them. I need help I work on a computer all day and my eyes are really starting to hurt alot. Any help you can tell me is appreciated
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