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.