To force yourself to
stay awake, without any alertness aid, in order to perform required duties/responsibilities, even though you had minimal (if any)
sleep the
night before.
He insisted he would scrudge through his
work day without any caffeine even though he only had 3 hours of
sleep the night before. He was looking forward to his evening nap before another long night, minimal
sleep, and another scrudging day tomorrow.