And, if part of why you can't sleep is because you are worrying about stuff, try this trick:
Talk yourself through the "worst case scenario" of whatever it is that you are worrying about, and then convince yourself that it really isn't that bad. For example, my worst-case scenario for the LSAT would be to score a 155 (the lowest score I have ever had, so it's reasonable to believe that I wouldn't score lower than that). What would happen? Well, I would apply to law school with that score, and because of my awesome GPA, and the work experience I plan to have before entering law school, and my strong writing skills and LOR's that I could get, I would probably still get into most schools that I am applying to.
AND... I'm still alive, my boyfriend would still love me, I still have two degrees, I'm still one of the smartest people I know, I am healthy, no limbs missing, my family is alive, I have place to live and food to eat, etc. etc.
See, the worst-case scenario isn't bad at all! I can sleep!