Doc prescribed 2 mg. tablets for me. It did nothing for me. So I upped my dose to 4 mg. I feel asleep after a while. The next time I took 4 mg. it did nothing at all for me. And the next time neither.

(Now I am on ativan. I alternate with 'melatonin', as I find that I keep needing to increase the ativan. Ok, maybe I'm on a small dose and need to up to a normal dose. I'm doing 1 mg. and now I need 1.5 mg. if I want to fall asleep. One night, I took 1.5 and didn't fall asleep, so I took a melatonin and seems the combination worked.
I do have some adrenal fatigue, which I believe is contributing to my inability to fall asleep. Looking into possibility of low thyroid, which by now I'm convinced is the case.)