Melatonin is decent. I have had this problem a lot and honestly the best solution I've come up with besides alcohol is forcing yourself out of bed every 30 minutes or so if you can't sleep, for 5 minutes at a time. Sit somewhere else and read your Kindle. Or just walk around.
I used to have bad weeks where one night of no sleep made me anxious about falling asleep the next night, which made the night after that shit too, and so on...the problem was that I basically associated my bed with not falling asleep which is something you want to try to get rid of. Getting out of bed if you can't sleep helps a lot with that