... We're told not to do this, and I totally understand why... BUT, it's not like driving after drinking which you can readily control. Say I've had a crap night, I can hardly call into work and say 'sorry, I feel tired, and as I have to drive in I'll won't be coming in'..... Or my daughter needs picking up from her dance class, and I've had a long day and feeling exhausted, I can't exactly leave her there...
And yet I've often heard and read glib 'never drive when you're tired' on MN and other places.
So what's the solution? A stiff coffee is the only practical answer as far as I can see, unless you literally haven't slept for days and are genuinely struggling to keep your eyes open, when you may need to accept you just can't drive safely.