Your contact lenses are a barrier between your cornea and the rest of the world. While this may not seem like a bad thing, it is. Your cornea, like every other part of the body, requires Oxygen. Too little oxygen, and complications begin to arise. So what happens when you fall asleep with your contact lenses in? Your cornea is being denied oxygen by the lens itself. This leads to a condition known as hypoxia.

Corneal hypoxia changes the rate of metabolism in the epithelium. This in turn causes a decrease in glycogen, and makes the cornea more sensitive and prone to adhesion and refractive error changes. Continued progression includes corneal ulcers.

Since the cornea is more adhesive, this increases the chances of any buildup on the cornea itself, including protein buildups, which cause bacterial infections and corneal ulcers. Short term effects include extreme intolerance to contact lenses. Lens intolerance can be overcome by RGP Contact Lenses, but by this point, you should just ditch them all together. Give your eyes a chance to heal, and suck it up and wear glasses.