I don’t know about use for mental health either, but currently having acupuncture for a trapped nerve in the lower neck which was causing me real grief;shooting pains down one arm and unable to sleep, etc. it’s been brilliant!
I think it depends on getting the right practitioner. Mine was recommended through a friend and yes I was sceptical, but right from the first session, it was like witnessing a miracle! It was like peeling away layers of an onion, in that he stripped away the pain in my arm and shoulder. Again not sure about mental health, but otherwise I’m a convert.