At one point i managed to toss and turn my head directly into the the bookshelves. I went "ow" and then went back to sleep.
This morning shelleycat asked me "why do you have blood on your forehead?" =P
Actually it's not that much blood, just a path about a centimeter wide and two or three centimeters long. And once i washed the bits of crusted blood off it's just a kind of bright pink patch. Still, more blood that you usually expect to find on your head when you wake up in the morning :)