Why can't I calm down?

I stress a lot... I think that's part of the reason I'm an insomniac. I can't do one thing at a time, I'm constantly multi-tasking and thinking about what I need to get done. Monday I stayed up until 2am working on the kid's preschool book (I'll post that later). It's done! Thank God that's over. Tuesday morning I was invited to join the "preschool/elementary commission" at my church so I went to their Informational Brunch. Yes, I joined.... do I ever say "no" to anything? I'm a sucker! Then I drop the kids of at school and think I'm going to take a nap. I lay down but can't fall asleep. Figures. So I catch up on some e-mails, etc. Pick the kids up and hours later I'm back at the church because I volunteered to help out 5:30-9. I'm exhausted when I get home but can I fall asleep? No! I take some Advil PM and eventually fall asleep somewhere around midnight.
So now that I have a major project done and I can return to my other projects. I'm just hitting roadblocks.... There's no reason for me to be stressed but for some reason I'm just wound.
I need to do something relaxing but at the moment I can't think of what that would be.
Any ideas?