Hey Socrilus, mirtazapine is a pretty strong antihistamine but that effect is known to wear off after a couple weeks, and also at the higher doses the more anti-depressant type effects will kick in (around 45mg), so you could try to stick with it for a little and maybe titrate up a bit faster than usual. It can be activating for most once the dose is up there.
TCAs can have sexual side effects but as I understand it, with some of them (especially the ones with 5-HT2A antagonism) it's better than SSRIs.
Wow that is the opposite of what I would have thought logically if it was some linear effect. I thought if its such a strong sedator (I knocked out within 15-20 mins) then it would keep doing that even more at higher doses. Is it some U shape type thing?