I had this one before. My stupid neighbour kept playing music at night and wake me up constantly. Eventually I ended up not sleeping even when the music was not on. I tried everything, I think I managed to calm myself a lot while lying in bed but still nothing. I also tried taking melatonin, but I can't say that it was a success story. I looked at ZMA, as someone training in gym it would have been a natural choice for me as a sleep aid, but ended up not using it, was scared of it causing acne.
What really helped me is using earplugs, like I said the music was not on too often, but I still used my earplugs and that must have given me the kind of relief that even if that idiot ****er turns on his dumb ass music I'm still safe. All in all it took a really long time to get back into sleeping properly, without earplugs or other help, but then it just happened automatically, on its own.
I think what you should do is shut out all the stress and everything that could possible disturb you. Look for things that disturb your sleeping pattern in the recent past.