First: is it actually necessary?
Sitting the exam on four hours of sleep having covered 70% of the material beats sitting it on zero having covered 85%. The extra content is worth less than the cognitive function it costs, and this trade is much more lopsided than it feels at 1am.
If you can salvage even three or four hours, take them. A partial night is enormously better than none — the falloff is not linear.
If you're committed anyway
- Triage brutally. You cannot cover everything. Pick what's most likely to appear and most recoverable, and consciously abandon the rest. Trying to cover it all means covering nothing.
- Retrieval only. No re-reading — you have no hours to spend on fluency. Questions, blurting, past papers.
- Caffeine early, not continuously. Front-load it. Caffeine at 4am is still in you at 10am when you want to be calm, not jittery — and jittery costs you marks.
- Move every hour. Stand, walk, get cold. Sitting still is how you microsleep through a chapter and don't notice.
- Do not learn anything genuinely new after about 3am. The encoding is poor and the anxiety cost is real. Consolidate what you have.
- Get a nap in if there's any gap at all. Even 90 minutes gets you a consolidation cycle, and it is worth more than 90 minutes of reading.
The thing that makes it much worse
Pulling the all-nighter and then continuing to study *right up to the exam*. You arrive exhausted and wired, with no space between input and output. Stop an hour before. Eat something. Walk. Let the anxiety come down — because the first twenty minutes of the paper is where a panicking, sleep-deprived brain loses the marks it stayed up to earn.