I took it for about 15 months (doses up to 25 mg) and the sedating effect didn't leave until I tapered off and got beneath 7,5 mg. However, to me the sedating effect was a godsend, as I wasn't sleeping at all without. I tried just about every sleep med in the book and then my pdoc put me on olanzapine 10 mg for delusions and it immediately rebooted my sleeping schedule.

However I do sleep a lot. Currently I'm not on olanzapine anymore, but on clozapine, but with both medications ("both" as in, the one or the other, I only ever took it together when switching) I sleep up to or even over 12 hours if my alarm clock doesn't wake me.