I'm a lark. I learned from the Brain Rules book described in the previous post that people can be categorized (ok, labeled) based on their circadian behavior; whether they are early or late chronotypes. Simply put, based of whether they are a morning person or a night owl. I am a morning person, so I'm labeled a lark. I could not name any other morning person, among the people I know. I was beginning to think that maybe I was weird. This site has a large table outlining the differences between larks and owls.
Here's a Youtube video of John Medina explaining larks and owls.
You can take online tests to see if you're a lark or an owl: MSNBC test and BBC test.