How about have the status bar appear after the first time you are dog tired ... until then it is greyed out.
You can even have a dialog "Man, I'm feeling like crap. I've trudged my way all around the area and am dog tired. What's interesting though, is one of my neuroindicators fired up and began letting me know just how tired I am. I'm going to have to pay a lot more attention to this from now on"