Wow - I have managed to survive the first week of classes without losing too much sleep. I had terrible trouble with falling asleep during pre-planning as I do every year. All the things that have to get done and not enough time to do it all. I am sure you know the feeling.
I did something unusual this year that I would recommend to any teacher out there. Instead of spending my last week of summer doing things to get ready for school, I took off for a fun filled vacation to Las Vegas. Now, not everyone would pick that destination, but I know that just getting away and relaxing right before going back to school kept me from stressing for the week. I told myself that it would all be there when I got back and I had already spent a great deal of my summer doing things for school. If you are anything like me, you take classes or attend workshops over the summer that you are not compensated for. So enjoy that last week before school next year...you will have so many fun stories to share with your colleagues when you do get back to school.