Random Fact #23: You can't sneeze while you're sleeping. If you really, really gotta sneeze, you wake up to do it.
Source: This Wikipedia article, third paragraph.
I just sneezed. It's after 1 A.M. and I've got sleep on my mind, and I started wondering if it's possible to sneeze while you're asleep. Apparently not! But I bet you never knew that another word for "sneeze" is "sternutation." There's a word to jazz up your vocabulary.