Given enough sleep-deprivation, adrenaline, and caffeine consumption; Caffeine and eating will join that list(there will come a time when this is useful).
Stay hydrated. When hydration seems to have joined the list, you are WAY past the point where irreversible damage to your body is possible.
Somewhere way earlier in this line of experience, you were better-off catching-up on sleep before whatever you were studying for.