I did a PTSD course in 07, and they talk all about the proper sleep hygiene. No caffeine after 4.30, don't watch anything on tv which over stimulates you, a relaxing shower etc etc. It taught us about the environment too. No bright clocks, No trying to sleep with the TV on etc.
It also talks about the bedroom only being for two things. Sleep and Sex.
What William said on the other thread about Valerian is worth a try. What I found though is that if something was troubling me and still on my mind, it did not matter whether I took stilnox or anything. It would knock me out for two hours then I would be awake for the rest of the night.
During the lesson, they also tell you that if you cannot sleep, don't just lie in bed. Get up and do something until that wave of tiredness sweeps over you again. It comes in cycles of like 90 minutes or so, but there is only a small window of about 10 minutes. You know when your on watch and you can't keep your eyes open. It last for about 10 or 15 minutes then gets a bit better.
My therapist has me writing down what is bothering just before lights out.
Currently I am on Valdoxan an anti depressant which makes you weary, and immovane which finishes the job. Last night a thousand things were on my mind though and I was a wake every hour or so.