Real talk: if you’re a regular contact wearer, chances are you’ve fallen asleep in your contacts at some point in time (or maybe even a few times). We all know it’s not recommended by eye doctors, but why, exactly? What’s actually happening in your eyes when you sleep with your contacts in?
You’re not ingesting a contact, it’s just sitting on your eye, but your body has to get acclimated to it. Contacts can also sometimes burn or cause dryness in the eye, too. Each individual’s tears are made up of a certain pH acidity and when you put a contact into your eye, the contact solution—not the actual lens— actually has a different pH, so your eye may tear to help wash that solution out.
If you have dry eyes to begin with, lenses may only exacerbate that. When we blink, we’re wiping tears across the cornea to help keep things uniform and clear, because when the cornea is exposed to air, it can become irritating.
Contacts need moisture once they’re removed from the solution they come packaged in, and if you already don’t have enough tears or suffer from dry eyes, lenses might only make that worse.
When we sleep, we lose ambient oxygen exposure to the cornea, which is needed to keep the cornea healthy. We are still able to get it in other ways—like through blood vessels—but we are getting less than we do when we’re awake. What a contact lens does is limit the oxygen even more because it creates a barrier between the oxygen and the cornea.
Some lenses—extended wear ones—allow the oxygen through though but if not enough oxygen gets through, you can experience what is called hypoxia (oxygen deprivation in a region of the body).
You also increase your chances of developing an infection, because bacteria can get onto the cornea and when your eyes are closed, there’s nothing to flush it away. The bacteria can then become opportunistic and literally start to eat away at your cornea.
If you fall asleep accidentally with your lenses in for just one night, you’re unlikely to experience any serious issues. But if it becomes a more frequent habit or you’re purposefully wearing lenses overnight that aren’t mean to be, you’re upping your chance of a serious health risk. If you start to notice that your eyes are extremely red (we’re talking very bloodshot), you feel like there’s something in your eye and it’s irritated all the time, your eye lid is looking inflamed, you aren’t seeing as well as you used to, or if when you look at an indoor lamp it feels like you’re looking directly at the sun, these are signs that you could have an infection and you should see your eye doctor right away.
So why even take a chance? Make it a routine to take your contact lenses out every night before you go to sleep.