Are those actually scratches? I know stupid question but I've woken up with those but they weren't actually scratches. The skin felt smooth and everything, I could just see the lines. I got them from apparently working out and somehow stretching the skin or something? If those are actually scratches though then I'm not sure.
You might want to look at doing a sleep study. You might be doing this to yourself and not know it. That or do you have a cat?
I am not trying to be funny on the last comment, i really do hope you find the cause.