Do not sleep with lenses that are not specifically designed for this. If you still fall asleep with the lenses, it may feel dry when you wake up. Do not remove them directly, but drip some lens fluid into the eye and wait for a while to pick them out when they do not feel dry anymore.
For some it goes straight on, for others it can take a few days to get used to the lenses. Partly because the eye's mucous membrane is not used to know the lens and partly that what you see can feel a little reduced or enlarged compared to how you see with glasses.