Newbie here.
I take 7.5 mg remeron (mirtazipine) for sleep. In years past I had been prescribed 15mg to begin and bumped 30mg when 15mg no longer seemed to be effective. (I'd estimate the time frame to be 6-9 months before raising dosage.) Within that same time frame of taking the higher dosage it too seemed to become ineffective. That was about 7 yrs ago. Just over a year ago I began having sleep issues again and Dr prescribed the 7.5mg, I was very doubtful and fully expected it not to work or maybe only work for a short time. To my surprise the lower dose has been very effective. I don't have the "hangover" feeling the next morning as I did with higher doses. It also seems to be working just as well as it did over a year ago! I would give it a try!
I will tell you that it does seem to take quite a while from when I take it to when I'm tired enough to sleep. It's definitely not fast acting. I usually take it 2 hours before my normal bedtime and when I lay down I usually fall asleep quickly, sleeping soundly through the night!! Give it a couple weeks even if at first you feel like it isn't working at first!
Wishing you the best!