The only non prescript
ion that I can think of off the top of my head would be something along the lines of benadryl or something like that. I know that you can buy just Diphenhydramine which is the thing in benadryl that makes most people sleepy. It's usually sold OTC as sleep tabs.
There's also the classic warm milk routine if you don't have an dietary issues with lactose. Umm... melatonin. A good turkey sandwich earlier in the evening for the tryptophan?
Those are the only ones that I can think of right off the top of my head, hopefully those help or someone else here will have some more suggestions for you soon. I've been lucky enough that when I have those nights that I am able to use ambien without any major side effects so I'm not that well versed in what to recommend.