Not sure if anyone else has seen this or not, probably so, but it was new to me. I have an evil gnome and it popped beside my sleeping sims bed. As I got to looking, its eyes were glowing and all of a sudden, my sim sat up in bed and acted like he was scared, then laid back down and went back to sleep. He had the moodlet, gnightmare or something to that effect. It happened so fast, I couldn't get a screen shot. Then, I moved the little gnome away from the bed and a few minutes later saw this...
I will say one thing, these little things are definitely evil. I know my sim didn't make that mess, because they were all asleep and this is upstairs.