I was taking Mirtazipine for insomnia and depression for several years and it always worked well but when I came off it earlier this year it had a severe adverse effect on my sleeping and I still haven't got back to a good pattern, I think long term use of these drugs actually damages your bodies natural ability to sleep. I have had some success with Melatonin which at least is more natural and as a last resort when I can't sleep at all and really need to catch up I take Promethazine which really knocks me out but also makes me drowsy in the morning. At least both of these do not mess with my body's sleep systems so much, but ideally I'd love to not have to rely on anything.

Playing meditation music overnight helps somewhat, as does sleep hygiene but that's basic anyway.