wanting to sleep, but can't

Last night, I hung out with some friends. So I come home and pick up the book, Nick and Norah's Infinite Playlist thinking that I just read one chapter while drinking my tea. Whoa - big mistake. I couldn't put the book down. I mean, it was one of those things that I was so curious to see if Nick and Norah get together at the end, that I keep reading and reading. And, then before I know it's 3 a.m. so I go to bed. But, then for some reason, I wake up at 10 a.m. and now I can't go back to sleep.