Exhaustion?

Is it normal at 5wks 2days to be completely DEAD? I am soooooo tired all the time :( I work fulltime 48-56 hr work weeks and when I get home on my weekends all I want to do is sleep !! I feel so lazy and unproductive and my husband has been stepping up and handling chores around the house like a sweetie but still! I feel bad for being so tired:( I also did not get enough food or water in yesterday because I was so exhausted. Is this normal?