Contact Lenses

Is it dangerous for me to sleep in my contacts?

When you sleep in contact lenses, they can cause imperceptible damage that can go undetected for years. Here’s what you need to know.

Joel Hunter, MD
Joel Hunter, MD
Refractive Surgeon, Hunter Vision Updated 11/01/18 11:21 AM

Contacts have gotten better and better over the years. You don’t have to rely on intuition to know that. Ask any nearsighted person over the age of 50 what contacts used to be like, and the answer might surprise you. Something about the experience of those early adopters makes the stories about contacts feel like you’re being woven a tale by an old sea captain. Almost weekly in clinic, I’ll hear something like, “those days, often as not all ya felt was the sting of salt in yer tears and ya prayed to yer God that you’d find the blasted thing in yer eye to fish it out before it cut ya to bits.” Then they’ll transition back into the quietly distinguished, nicely dressed older woman or man I was talking to the moment before.

Contacts had a unifying, deep impact on early adopters. For those of us who grew up soft, never having to deal with what felt like live cinders in our eyes, it’s difficult to understand why contacts can be dangerous. This article is for those who wonder whether it’s dangerous to sleep in their contacts—a.k.a. people born after 1970. I can’t remember the last time I talked to someone born before the 70’s who would ask about sleeping in contacts. They’d sooner ask if you’d be foolhardy enough to “try and kiss a shark while yer wearin’ meat pajamas.” They were forged in fire, those early contact lens wearers.

Today, contacts have a much greater ability to stay slick and smooth. This is called “wetability” and I promise it’s a real term, though I understand your reasons for wondering after all the pirate quotes a moment ago. Wetability, along with increased oxygen transmission, makes modern contact lenses more comfortable. Compared to previous generations, today’s contacts feel a lot more like they’re not there. This is why people who’ve worn nothing but current, high-tech contacts can ask the question of whether sleeping in them is okay. Sometimes people do fall asleep in them, and then they wake up and their eyes are still working and all is well. I often meet people who sleep in their contacts for months(!) at a time. I’m amazed and confused that their eyes sometimes look alright. But there’s another side to that coin.

For every ubermensch who sleeps in his or her contacts for long stretches with no difficulties, there are many more whose eyes have minor or major complications when sleeping in contacts. The comparison can be made to the stories of 96-year-olds still working their farms despite smoking three packs of cigarettes every day since they were 8. The reason those borderline-tall-tale type stories are exceptional is because they are, well, exceptional. Stories usually thrive in the fascination surrounding the exceptions in any setting. Statistics, which are much more boring and much more applicable, are reserved for what happens to everyone else.

Statistics say that if you smoke a bunch for your whole life, you won’t do much farming when you’re in your nineties. They also say that if you sleep in your contacts a lot, you’re much more likely have a problem with your eyes. When you sleep, especially in the wee hours of the morning, you make far fewer tears. And while your eye usually can manage a slick piece of space age contact lens material hydroplaning around on its surface, it needs those tears to do it. Your eye runs into problems when everything dries out and your contact lens becomes a tacky piece of plastic stuck to your cornea. The contact can be moved at that point, but usually some cornea is coming with it and leaving a divot behind.

Eyes heal quickly, and those abrasions on the surface go away in a matter of hours, but if you’ve ever had a hangnail or a paper cut get inflamed or infected, you already know what happens when things don’t heal quickly enough. The chances of having an abrasion on your eye turn into an ulcer are directly proportional to how many times you have those abrasions. Part of what increases the chances of inflammation over time, even more than a few extra rolls of the dice, is the new blood vessel growth on the eye which is stimulated under all these conditions.

The reason exceptions exist, in the case of contacts, is because of something akin to a selection bias. When you sleep in your contacts and your eyes feel okay, you likely have a condition akin to “anti-dry eyes.” You’ve got tears to spare and you happen to tolerate contacts well. It’s not that it can’t cause problems over time, it’s just that people who would get those problems early don’t usually want to sleep in their contacts in the first place. It hurts when they do. So the stories we hear about people with contacts in for months at a time are the select few who do it because they actually can without waking up in misery.

It’s not the most medical-sounding comment an ophthalmologist should make on this, but in general, if your eyes are in imminent danger, you’ll know without a doctor telling you. Here’s the issue: there are times when problems build up slowly over years, and you can’t know until well after you wish you’d never slept in your contacts. And while that sounds like typical medical advice, it’s still relevant and true.

The danger of comfortable contacts is that they’re comfortable. When they’re used in a way not intended, the little imperceptible bits of damage done over the years can go undetected a long time. I’m not an alarmist saying you’ll end up with an eyepatch like a pirate if you sleep in your contacts. But I am saying it wouldn’t be a bad idea to learn from the tales of the people who came before you—people who now sound eerily like someone who’d wear a pirate patch.

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