I recently switched from Trazadone, was up to 150mg, also take 3mg Melatonin and generic Ambien when I cannot fall asleep. Was sleeping pretty well on 150mg but seemed to have to stop working. I usually take my meds 2 hours before I want to be sleeping, sometimes they kick in within an hour, depends upon how fatigued I am. I recently had a couple of sleep studies done. I have obstructive sleep apnea. Now sleep with CPAP machine, since end of November 2009. Recently had follow up with CPAP dr and he made some adjustments, not my medicine Dr. Saw another specialist that is supposed to help with our condition, and he is working on my sleep. Stopped Trazadone and started Mirtazapine of 30, did not keep me out for 7 to 8hours is what I am aiming for. Split tab the last 2 nights so dosage is 22.5 of Mirtazapine and I am only supposed to increase when I am not getting 7 to 8 hours of sleep up to 30mg a night. Will see the Dr in a month from now. I am sure our meds are going to need to change with time since our bodies get used to them!