I work for a contact lens manufacturer and let me tell you it is bad to sleep in contact lenses that are not designated for extended wear, even naps.
When your cornea is oxygen deprived (hypoxia) it swells and becomes very dry (the peeling). You leave yourself open to conjunctival infections (pink eye) and damage to the epithelium, stroma, and endothelium (layers that make up the cornea), resulting in cysts and infections.
Don't peel your lens. Hydrate your eye before you do it. You are peeling away a layer of the epithelium when you do that!
If you want to sleep in your lenses have your doctor prescribe a lens made of silicone hydrogel, which allows more oxygen to the cornea.
Off the soapbox now. I guess that's more than you really wanted to know about the effects of corneal oxygen deficiency! But you should really take care of your eyes!