I've been on anastrozole for 5 months and so far my only major symptom has been insomnia. I am up to an average of 5 hours sleep a night at this point. I am also having chronic mild headaches but not sure if that is related to my chronic migraines or the anestrozole. I will see my neurologist in Sept and discuss with him. I did lose some of my hair after my first surgery (8 hours) but that has pretty much stopped now. I had IDC, Mucinous type, 2 tumors, Stage 1 and Stage 2. I elected for bilateral mastectomy with natural reconstruction using my own fatty tissue. I am the most blessed woman as I did not need Chemo or radiation but anestrozole is wreaking havoc with my emotions and depression. Good luck and blessings to you.