I cut caffeine out of my diet, (apart from chocolate) which has more or less cured my issues with sleeping. I think I could start drinking it again, but only pre mid day.

It is very hard to do (headaches, sleepy in the day etc), but worth a shot.

I also use earplugs, which I find it very hard to sleep without now (unless drunk). They not only block out noise, but you get conditioned that when you put them in it's time to sleep, it kind of gets you into a sleep mind set.

The other thing I find helps is if I find my mind racing I try and slow my breathing down as much as I can. I think it works on two levels, I focus on breathing and free my mind of jumping all over the place and it also slows your heart rate and therefore oxygen to the brain, which I think has the same effect :P