In college, this happened and I slept three straight days. I wasn't sick, just exhausted. My roommate kept poking me awake to make sure I wasn't dead. She wasn't the greatest roommate, but at least she made sure I kept breathing.
Several years ago, when I was volunteering a lot, I helped out for a concert and walked the equivalent of eight miles and about twenty flights of stairs. It took me about a week and some prescription strength vitamins to get me back to good.
I say all this because running a farm, dealing with my teeth and not eating properly, rehearsing for the play, getting the barndo in order and trying to keep up with all my social activities, I hit the wall in the middle of last week. So I've been sleeping a lot this weekend and I'm getting better. Just know, I'm seeming to work more as a lady of leisure than I ever did when I worked full time!