What it does
- Attention and executive function improve after aerobic exercise, on a timescale of hours. Studying after a run is measurably better studying.
- Sleep quality improves, and sleep is when the day's learning is consolidated. This alone would justify it.
- Mood and anxiety — one of the better-supported non-drug interventions there is, and exam anxiety is expensive in marks, not just in feelings.
- Stress tolerance. Revision periods are long and grinding, and the thing that breaks first is usually the person, not the schedule.
The trap of cutting it
Cutting exercise to buy an hour of study feels like straightforward arithmetic: one hour in, one hour out. But the hour you gain is a worse hour — you're more tired, less focused, sleeping badly — and the effect compounds over a revision period until you have many more hours of much lower quality. That is the wrong direction on both axes.
This is the same error as the all-nighter: trading the quality of your cognition for the quantity of your input, at a bad exchange rate you can't see.
Practically
It doesn't need to be much or serious. A brisk twenty-minute walk is a real intervention. Something aerobic, most days, ideally not immediately before sleep. The point is consistency rather than intensity, and the bar should be low enough to survive a bad week — because a bad week is exactly when you need it.