MAny years ago I got myself really stressed out with driving all day in city traffic. I developed an ulcer and went to my Dr's. He gave me medication for the ulcer and asked me to see the practice psychologist. She gave me a relaxation tape that worked a treat. It was a very simple system of concentrating on the muscles in your body starting from the toes to the feet to the calves and so on until you got to your scalp. The system involved you concentrating on the muscles one group at a time and positively relaxing them. By the time you get to your head neck and scalp you are so relaxed that you drop straight off to sleep.
The benefit of relaxation therapy is that you need not worry about any medication.
Another way of getting off is to get into a set routine at night, going to bed at a certain time, reading for say five or ten minutes and then closing your eyes. This also works well for me, especially if the book is a bit on the dry side.
I have also used the technique of deliberately thinking of nothing. It is self-explanatory but quite hard to do. With practice you can stop you mind racing off on tangents when you should be sleeping.
Hope some of this helps, sweet dreams
Michael