Oh, and you are in AU. There is a British AP many swear by, in low doses, as the gentlest sleep medicine without metabolic effects, unlike Zyprexa and Seroquel.

http://en.m.wikipedia.org/wiki/Clozapine

Several notes - first, it has a confusing name, as if it were a benzo. Second, bad things happen on high doses. If the smallest dose, 25 mg, is sufficient to keep you at bay, then it probably is one of the safest routes for you. Taking it PRN only when you feel so elevated that you cannot sleep is probably THE safest route. I am considering it, too, as al alternative to relying on Zyprexa prn. Note that you will need to know yourself REALLY WELL to try the PRN approach, because you will be nipping problems in the bud, and to nip something in the bud, you must not let that somwthing grow into a big plant in the first place.