This made me chuckle :)
Here's the bit...The rest of the site is quite interesting as well.
Not boors that surprise you by ringing your doorbell with a fistfull of Watchtowers, but those sudden jerks that you make when you're asleep. A reasonable (but not proven) evolutionary hypothesis is that it was a defensive response that developed when we slept in trees. Any slight sense of unbalance would promote an automatic jerk and instant awakening. Sometimes it accidentally goes off even nowadays, even when you're planted firmly on your Certa Perfect Sleeper. That's the beauty of evolutionary explanations: there has to be one, and it has to make sense--but you don't have to commit adamantly to it. A better one may present itself as more evidence is considered. Think of a good "creationary" explanation for those sudden jerks, preferably better than "God made us that way and He moves in mysterious ways."