In my experience (I won't go into the details) but +1 to the notebook and try self-hypnosis. Unfortunately, I was taught it by medical professionals (no, really, I won't go into the details) and it is not easy to teach yourself but I now have a routine which involves deep breathing exercises then tensing every muscle I can feel, and relaxing them individually up the legs, then up the arms, then chest and neck. I do this in tandem with breathing exercises (breath in whilst counting to 5... breath out whilst counting to five, relax and repeat)
Having written down whatever it was that was bothering me in the first place, I'm usually gone again before the end of that.
Plan B, depending on how anal you are, count in binary on your fingers. You can get to 1,023, which is much better than using decimal when you can only get to 10.
If you can't count in binary, so much the better. Clear the crap out of your brain and replace it with something which you won't worry about.
I know some people who lie awake worrying if they have insomnia. Don't lose sleep worrying about sleeplessness. It seems frivolous but it isn't. If you wake up, read a book. Stay in bed and relax but don't just lie there, in the dark, worrying about shoot which isn't worth worrying about. Relaxing in bed is still giving your body recovery time, find a crap book to empty your mind as well.
If you find yourself waking at 3:30 every morning, that's a sign (IMO) that you should see someone with better qualifications than the armchair shrinks on CC. And no, I'm still not going into details.