"i suffered a neurotoxic reaction to another drug, metronidazole; it caused lesions for form on my brain.  this led to neuropsychiatric symptoms, including severe anxiety, major depression, suicidal thoughts (just a month before, i was happy), and horrible insomnia.  i was given mirtazapine and it greatly helped, especially the insomnia.  i had barely slept for eight days--even  ambien couldn&#039;t knock me out after the first night (i&#039;d never taken a sleeping pill in my life and even ambien couldn&#039;t help).  mirtazapine was a life-saver, literally.  metronidazole had overstimulated my central nervous system and mirtazapine helped to calm it down.  it took longer to treat the other symptoms, but they, too, resolved."