No Sleep for Me

I love sleeping. Often during the day I think about how much I'd love to be getting all warm and cozy in bed and taking a long fabulous nap. So why is it that when I actually HAVE to go to sleep I can't?! It's 1am, I have to sub tomorrow (today), I'm tired...but just cannot fall asleep. I was laying in bed for 2 hours before I got up to wander around. 2 hours! Such a waste! Grrrr...