One could try GABA inducers like 5-10g L-Glutamine in a cup of water before bed. It doesn't force falling asleep like Ambien but seems to relax the body and once you fall asleep, you sleep deeper and more restful.
Other GABA inducers are NAC or a low dose Glycine. The high dose Glycine seems to prevent sleep so it is not a good starting one.
GABA inducers increase the production of GABA. They all work in my case but suppress the ability to orgasm so I am always deciding between sleep or sexuality.