You really want to take that 3 p.m. nap, but you don't feel like taking out your contacts. After all, what's the worst that could happen? We spoke to an eye surgeon to find out.

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Following is a transcript of the video:

Irina Belinsky: Some contact lens brands say that it's okay to sleep in them, but as a general rule, it's really not. Contact lenses are safe, but they're safe if you take care of them appropriately, and part of good contact lens hygiene is not sleeping in your contact lenses. Think of the contact lens as foreign material in your eye. It's sort of like a sponge, and to be comfortable, the contact lens needs to be moist, so, it absorbs moisture from your eye, and it can also trap bacteria, and so, it's very important to take your contact lenses out to clean them periodically.

Leaving them in when you sleep can cause an eye infection that can sometimes be really, really bad. A lot of the infections can be mild and go away with antibiotic eye drops, but some infections can be really, really severe, and even if they go away, they can cause scarring of the surface of your eye, which is the cornea, and that scar can cause sort of a permanent change in your vision. Sometimes an infection can be devastating, and it can completely cause the eye to scar to the point that someone might need a corneal transplant or lose vision completely.

Really serious blinding kind of infections related to contact lens wear are rare, fortunately. If they were common, then nobody would ever wear contact lenses. So, they are exceedingly rare, and they usually have to do with really, really bad contact lens hygiene. So, good contact lens hygiene has to do with a few things. One, knowing if your contact lens needs to be changed every month or every two weeks and trying to stick to that, even if you have to put a little reminder in your calendar. The more common thing that we see is just contact lens overwear. The cornea gets devoid of oxygen. So, a contact lens does start to break down over time so it doesn't have a smooth surface. It's gonna form micro-breakdown kind of edges, and the contact lens will also dry out. I mean, your eye just doesn't have enough moisture to keep a contact lens in there forever.

If you think of the contact lens as a sponge, like the sponge in your kitchen, you have to clean it every so often, and you might even have to replace it every so often, because it just doesn't do the job right anymore. A contact lens can become kind of folded and entrapped in the eye underneath the lid, so, I have seen that where patients come in with chronic red eye, and you look around very carefully and sometimes, and this is also rare, but you can actually extract a contact lens that has probably been there for months.

It can happen if you put it in wrong. It can happen if you sleep in it. It can happen if you don't take it out, or if you forget to take it out. Take your contact lenses out. Don't leave them in. Take them out every day.