Are psychiatric medications harmful to a persons mind and body?

It sounds like you may have been reading some Scientologist propaganda. They are really anti-psychiatry because L. Ron Hubbard was diagnosed as a paranoid schizophrenic and wouldn't comply with his doctor's treatment. That being said, considering what you're taking, I'm surprised you're awake. Seroquel is an anti-psychotic that can have irreversible side effects like tics and tardive dyskinesia. It is NOT indicated for anxiety or insomnia. It's only approved for psychosis in schizophrenia and bipolar disorder type 1. Mirtazapine is not a very good antidepressant, and it can make you extremely tired or drowsy. I was on it, and it made me sleep 14 to 16 hours a day and have horrific nightmares. I think you need a new doctor. I could recommend a lot of different meds without the heavy side effects of these drugs. They're totally inappropriate, and it seems like your doctor is trying to sedate you heavily to treat anxiety, and that doesn't work.