Agrona Devoncroix
People have actually self harmed in their sleep, it's basically like sleep walking, moving in your sleep, talking and snoring. People do all sorts of things, and harming your self (not on purpose obviously) can be similar to that.
i agree, alto it could be a demon or a very mad ghost, you could actually be reacting to your dream.
people have sometimes been known to do such things. my friend gets hot while she is sleeping and in a form of sleep walking has folded her pajamas and laid them at the end of her bed. (it is actually annoying when i sleep over and am woken up by her stripping and folding...)
do you have long finger or toe nails? maybe something sharp close to your bed?