Sky, how much magnesium do you take? It could serve as an excellent augmentative sleep agent. Alone, it's not going to do much for most people, but alongside a sleep drug, it can ease you into sleep mode.
I take 300-400 mg of magnesium salts a night, alongside a tricyclic that is known to induce sleep, trimipramine. Doxepin works better for some people, but they don't make a dose small enough for me, and I just hate mussing around with those itty bitty capsules, to dump some out. Never know exactly how much I dumped out, either.
Both of these tricyclics really hit the sleep-inducing histamine receptor. Hard. For antidepressant purposes, these drugs are considered to be too "dirty" for common use, because they are so stunningly sleep-inducing. Maybe you're looking for that side effect? And, along with the third member of this group, amitriptyline, there may be pain suppressant properties that are yet another "side effect".
If Benadryl makes you drowsy, then you know that histaminic drugs that cross the blood/brain barrier are a good choice for sleep induction.
I really don't know your story, if you've been there and done that, but if not......you still have untried options.
The magnesium and the tricyclic make it so I almost can't not got to bed. I can't fight that. And I've had pain and insomnia ruling my life for years.
Lar