Sleep really is so important. I used to suffer horribly with insomnia. Sometimes it revisits. My general rule is that I have got very little sleep for 2 nights, I will take something (like Tylenol PM, nothing major) on the third. I've developed my own system for sleeping but I don't know that it would work for anyone else. I just have to get myself very emotionally involved in an inner story that has NOTHING to do with my life. It has to have a strong emotional pull (I think it may be ... possibly past life related... but not sure) in order to keep my attention... otherwise my mind is right back to this life and struggling to stay connected to it. It's bizarre.
You could always try progressive relaxation or guided imagery or something. I like to imagine and feel myself going down an elevator... floor 10, 9, 8, etc... and with every floor that i go down, I become heavier and more relaxed, sleepier. Once in a while that works.

Another thing that helps some people is to write down the things that are worrying you or occupying your thoughts and then close them in a notebook (maybe even put a rubber band around it) and decide to put them up for the night.

Good luck. I hate insomnia. Pills are not evil (but the heavier duty ones make you groggy and mess up your morning).