I am 54 years old and suffer from anxiety disorder. Every morning I wake up feeling weak and tired even though I get 8 to 10 hours of sleep. I went to my PCP and she did blood work and said, everything looked fine except my Vitamin D was low, she gave me 50,000 iu of vitamin D to take once a week for six weeks along with calcium, but I still feel weak and tired everyday. I take Xanax 1mg., but I only take it when I really need it. I use to break it in half and take it before going to bed, but I stopped that over six months ago. Does anyone know what might be causing this weak tired feeling ?