Honestly, it's all mental. If you cannot go to sleep, then get in the right state of mind. If you have something troubling you, in this case not being able to sleep is what is keeping you from sleeping, assuming nothing else has happened. Your worry over that is blocking your brain from producing the hormones your body needs to sleep. For me, living the life I do, worry about everything, encounter stress at every corner, and it can be really difficult to let those things go long enough to sleep. But I do sleep, all the time. I know it is more important for me than those things I stress over, and as such all I have to do is just meditate for about ten minutes, slowly lie down, and I'm out within the next half hour. So the key in this is meditation, if you are not sure how just use Google to find a good site describing the right state of mind to be in while meditating.
