i have lomng since stopped trying to wrestle with the PD induced sleep disoder which finds you sleeping very mixed up amounts and times of restful sleep. Melatonin didn't help adjust to "normal hours". IF i "must sleep" i take 2 mg of Clonazepam, that usually deos the trick and it's not very habit forming if you don't use it every night(imho). Clonopin (or Klonopin) is a benzodiazepine , so just be careful.
I think that Seroquel is a mild dopamine antagonist, but has been used successfully by many here over the years. I still think it's a rather "big gun", and that there are perhaps better sleep inducing agents out there, however, most of these things cause some form of dependancy if used on a regular basis.