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.