I remember having a nightmare a couple of years ago. The usual one, revolving around heights. Being thrown out of an air plane, straight into a lake. In no time, I would be under the water, loosing the last bit of my breath. Drowning, basically.
I woke up, just to realise that I have pushed my own head into a pillow, and could not breathe. I didn't know whether I should laugh, or be freaked out by my own sleeping idiocy.