How can I sue my old workplace?

I had been working for a major department store from August 2014 to the present (April 2015). I was treated unfairly and unkindly even with my mental disabilities. I was working 10-12hr shifts ending between 12-2am then to come in the morning for an opening shift; and this affected my normal sleep pattern. Because I would come home at such early morning hours, I would come home exhausted and forget to take my medicine for my disorders. Because this happened so frequently, my family began to notice a change of my behavior, and I became combative when it came to my medication. This caused me to suffer episodes of both bipolar mania and bipolar depression. And as if I didn't already have enough hours, they began pressuring me into staying later or coming in earlier. I felt that my store manager asked me to close because she knew I'd say yes. I feel like they gave little or no consideration to me as an individual with a mental disorder. Their blatant disregard for my well being is sad.