What to do when you can't sleep?

This morning I woke up at about 2:30 and couldn't go back to sleep. I thought about reading a little in the BoM (that usually makes me drowsy:), but decided the light would wake Ben up. So finally at 3:30 I decided I would exercise. And I did, right there on the floor by the bed for almost 30 minutes. Push ups, crunches, side planks, etc. Let me tell you I fell asleep with in 5 minutes after that! And when I woke up with Ben, I was so sore and I could barely wake up. I went right back to sleep before he was even out of the shower. I woke back up when he opened and closed the garage door (it's right below our room) so I read the BoM. I have to do it then while the kids are asleep or it won't get done. Then I went to sleep again til the kids woke me up.