About one-third of all contact wearers fall asleep with their lenses in, and most wake up with nothing more serious than a little dryness they can blink away with a few eye drops. Some contacts are even FDA-approved for sleep.

The Centers for Disease Control and Prevention (CDC) say it’s not. That’s because sleeping in your contact lenses makes you six to eight times more likely to get an eye infection.

Serious eye infections can lead to corneal damage, surgery, and in rare cases, loss of vision.

It’s important to note that these infections can occur whether you’re wearing contact lenses to correct your vision or purely decorative lenses.

According to researchers, just about everyone.

Studies show that around 85 percent of teenage contact lens wearers, 81 percent of young adult contact users, and 88 percent of older adults engage in at least one behavior that puts them at risk for an eye infection.

The most common risk taken? Sleeping or napping in contacts.

Corneas come into contact with bacteria every day, yet infections rarely occur. That’s because a healthy cornea is part of your eye’s natural defense against contaminants. But to function in a healthy way, your cornea needs both hydration and oxygen.

While you’re awake, blinking keeps your eyes moist, and oxygen can flow in through the tears you produce. Contacts fit over the surface of your eye, significantly cutting the amount of oxygen and moisture your eyes can access.

While you’re sleeping, that decrease becomes even more severe. Without enough oxygen — a state called hypoxia — the cells in the cornea lose their ability to fight bacteria effectively.

Sleeping in your contacts could result in one of these serious eye conditions:

Bacterial keratitis

Bacterial keratitis is an infection of the cornea, generally resulting from either Staphylococcus aureus or Pseudomonas aeruginosa, both of which are bacteria found on the human body and in the environment.

You’re more likely to have bacterial keratitis if you use extended-wear contact lenses, if your immune system is compromised, or if you’ve had an eye injury.

According to the National Eye Institute, infectious keratitis can usually be treated by eye drops, though more serious cases may require steroid drops.

If left untreated, your cornea could be permanently scarred by the infection.

Acanthamoeba keratitis

The amoeba that causes this infection can be found in lots of water sources, including tap water, hot tubs, pools, lakes, and rivers.

The American Optometric Association says acanthamoeba keratitis often occurs at the same time as a microbial eye infection. So, if you’ve been rinsing your contacts in tap water, swimming in them, and also sleeping in them, you may be at risk.

Treatment for this condition requires a long regimen of medicated eye drops, and if the eye drops don’t resolve the problem, you may need surgery.

Fungal keratitis

Researchers have found that fungal keratitis is most common in regions with mild temperatures and tropical weather.

Sleeping in your contacts increases your risk of getting fungal keratitis. But most people who get it also have experienced some kind of eye trauma involving a plant, branch, or stick.

Treating fungal keratitis quickly is important, because if left untreated, it can cause you to lose sight in the infected eye. In fact, fungal keratitis is among the leading causes of blindness in India.

If you fell asleep with contacts in, remove them as soon as possible. If you can’t remove them easily, don’t tug at them. Place several drops of sterile contact solution in your eyes, blink, and try again. The extra lubrication should help dislodge them.

Don’t wear your contacts for one full day, and pay attention to how your eyes are feeling. If you notice any of the symptoms of infection, contact your eye doctor immediately.

Signs of eye infection

The Cleveland Clinic recommends that you see your physician or eye doctor right away if you notice any of these symptoms:

  • blurred vision
  • discharge coming from your eye
  • redness
  • excessive watering

If you think you have an eye infection, put your contact lens in a plastic container, and bring it to the eye doctor so it can be tested.

Because lenses come into contact with the sensitive tissues of your eyeball, the American Academy of Ophthalmology advises that you observe these precautions:

  • Don’t swim or get into a hot tub while wearing your contacts.
  • Wash your hands with soap and water before handling contacts.
  • Rinse and store your lenses only in contact lens solution, never saline solution or tap water, which can’t disinfect your lenses.
  • Rub your lenses with disinfecting solution to clean them before you place them in your storage container.
  • Replace the disinfecting solution in your lens case every day. It’s not enough to just “top it off.”
  • Replace your lenses and your lens case often — at least every three months. Never use a cracked or broken lens case.
  • When you travel, buy a special travel-size contact solution. Don’t pour solution into a plastic container that may have been exposed to contaminants.

Sleeping in contact lenses is dangerous because it drastically increases your risk of eye infection. While you’re sleeping, your contact keeps your eye from getting the oxygen and hydration it needs to fight a bacterial or microbial invasion.

If you do fall asleep with them in, remove them as soon as you can, and let your eye recover for a day before wearing lenses again. Practice good contact lens hygiene to protect yourself from infection.

If you notice any of the signs of infection, see a doctor right away so that you can treat the problem before serious damage occurs.