Any warm drink, a fish oil capsule (or any type of oil), a vitamin D pill, and calcium pills. Vitamin D can cause problems, so don't take more than one dose per day.
I know what works for me, but YMMV. Back when I suffered from depression I'd play hell trying to get to sleep. My 'go-to' remedies were 1) melatonin (which worked great except for the wild dreams), and 2) an antihistamine and a shot of Jack.