Since you have had luck sleeping with antipsychotic meds, which tend to be sedating, and do not sleep without them, I wonder if there is an underlying sleeping issue/sleep disorder?
I cannot sleep without some form of medication. I like to limit my exposure to the antipsychotic meds, so my pdoc prescribes temazepam, which is a benzodiazepine. Not all pdocs will prescribe benzos. I actually have sleep terrors, from C-PTSD.
Sleep can be disturbed for a number of reasons. Sometimes, it is mood-related (as in hypomania, for example.) Yet, other times, it could be for a myriad of reasons.
Have you ever thought of seeing a sleep specialist?
I hope you find answers and, most of all, sleep!

WC