There was a program about a guy who, in his sleep, killed his mother in law an age ago, but I remember it well. Story goes he got out of bed, dressed himself, drove to his in-law's 50 miles away, let himself in with the key under the door mat, stabbed his mother in law whilst the father in law was downstairs asleep in front of the tele, left, slamming the door which woke the father in law, who checked to see who it was, saw it was only the son in law, went up to bed and found his wifes body all wrapped up in bloody sheets! You don't want that, do you? Go and see a doc.