It happens to pet owners all the time: You're sitting there wondering what your dog or cat is staring at when you suddenly realize they aren't staring at all - they're simply sleeping with their eyes open.

Can humans sleep with their eyes open?

The answer for up to 10% of the population is yes. But while sleeping with your eyes open may sound harmless, there are plenty of reasons why it's a good idea to keep your peepers shut when you want to get some shut eye.

Why Should You Sleep With Your Eyes Closed?

There's a simple reason your eyes have eyelids to begin with-they help protect the eyes from foreign matter. While you're awake, blinking helps clear your eyes of dust or other particles that might get in your eye; blinking also lubricates your eyes to make sure they don't get dry or irritated. When you're asleep, though, you stop blinking, so keeping your eyes closed is the best way to also keep them safe.

Plus, sleeping with your eyes shut cuts down on outside stimuli such as light or movement that might wake you or otherwise prevent you from getting a deep, restful sleep.

What Are the Dangers of Sleeping with Your Eyes Open?

People who sleep with their eyes open often wake to find their eyes dry, red and irritated. That's annoying and painful in the short term, but there are also potential long term problems that can occur if you chronically sleep with your eyes open.

Sleeping with your eyes open on a nightly basis can cause your eyes to become inflamed and can also lead to dry spots, ulcers or even scarring on your cornea or on the inside of your eyelids.

Why Do People Sleep with Their Eyes Open?

So what causes some people to sleep with their eyes open in the first place? While the phenomenon isn't entirely understood, the most common cause is a sleep disorder called nocturnal lagophthalmos, which basically means an inability to fully close your eyelids at night. Sometimes this is triggered by skin disorders or even botched cosmetic surgery, but usually it's an issue with your facial nerves.

What Should You Do If You Sleep with Your Eyes Open?

Luckily, most people who sleep with their eyes open don't suffer any serious side effects. As a result, treatment can be as simple as using fake tears or eye ointment before bed and after waking to ensure the eye stays lubricated. Sleeping with a mask over the eyes can help as well.

For more serious cases, surgery may be required. And in some instances, gold weights are even implanted in the eyelids to make them heavy enough to close on their own!

If you sleep with your eyes open, consult a physician to find out what kind of treatment is right for you - and try to give your peepers the rest they deserve.