Other than being addicted to EverQuest, lol, I usually don't have problems falling asleep other than during a work night, I always think that I'll wake up too late and not make it in on time, or I'm worried that the next day will be total hell with my job.
I sleep better on my days off, and if that causes a problem, I'll usually eat ice cream or something before going to sleep, I did that last night and I slept 11 hours. I guess I needed it after staying up till 2 a.m. playing EverQuest.
I had trouble falling asleep about 5 years ago at night when my ex-husband left me, he was very abusive, when this occurred I was always scared that he would come back and kick the crap out of me or something.
I had to repeat to myself over and over "he doesn't know where you are, and your in a place he can't harm you" eventually it took into my brain and I was able to sleep after about a year of doing this.
My suggestion is to "train" your mind into thinking that you are o.k. and if needed just repeat it to yourself over and over, eventually your sub-concious will allow you to feel that way and you should be fine.
I'm not a doctor, but it worked for me, so that would by my suggestion