I Don't Think I Need Mirtazapine For Sleep. I Am

I don't think I need mirtazapine for sleep. I am not depressed. Why does my doctor want me to take it?
I have not be able to sleep since my husband died 5 years this Feb. I since moved 170 miles last Oct.
to Indianapolis where my daughter is and grandchildren. I am not really happy living in a retirement apt. but know I could no longer take care of a big home. I am 73 years old and carry the oxygen tank around my neck when I go out. I have had trouble sleeping for a long time but I am not depressed. I also have a tumor in my heart chamber. Too risky for surgery. I don't worry about it. Do you think I need that strong of medicine? I don't. Thank you