In exam season, most students treat sleep, food, and exercise as the things to cut to make more time for revision. This is one of the most common mistakes anyone makes about how exams work.
Your brain is the thing that's going to do the exam. The brain runs on sleep, food, and physical activity. Cutting any of those to revise more is like trying to drive faster by taking petrol out of the tank. It feels productive. It actively makes you worse at the exam.
This article is short because the rules are simple — but they make a measurable difference to exam performance. Treat this as a checklist, not a sermon.
Sleep
Aim for 8–10 hours a night. This isn't optional or a "nice to have" — sleep is when your brain takes everything you learned that day and files it into long-term memory. Without sleep, the learning hasn't happened properly.
- Don't revise in the hour before bed. Your brain needs to wind down. Revision right before sleep keeps your brain in study mode and stops you actually resting.
- No caffeine after about 4pm. Caffeine stays in your system for hours, even if you don't feel it. Late-afternoon coffee makes for a worse night's sleep, which makes for worse revision tomorrow.
- The night before an exam, go to bed at your normal time. Lying awake worrying does nothing useful. If you genuinely can't sleep, get up and read something boring for 15 minutes, then try again.
- Cramming all night before an exam is the worst possible strategy. You absorb almost nothing, and you sit the exam exhausted. You'd score better with 8 hours of sleep and no last-minute revision.
Food
What you eat directly affects how your brain works. The differences are noticeable within hours, not weeks.
Slow-release carbs and protein, not sugar. A breakfast of porridge, toast, eggs, or anything similar gives your brain steady energy for hours. A sugary breakfast gives you a fast spike and a crash about an hour later — usually right when you're sitting down to revise or in the middle of an exam.
Drink water. Even mild dehydration measurably cuts concentration. A water bottle on your desk is one of the easiest changes you can make.
Don't skip meals to revise. Lunch in front of your books still counts. Skipping food entirely makes your brain run on empty, which makes everything harder.
Energy drinks are the worst option. They give you alertness and anxiety in equal measure. The crash afterwards is real — 60–90 minutes of useful focus, then an hour of worse-than-before fog. Avoid.
Exercise
A 20-minute walk improves concentration for the next 90 minutes. This is well-documented. Movement is one of the easiest ways to revise better.
You don't need to go to the gym. Walking, cycling, kicking a ball around, dancing in your bedroom — all count. Anything that gets your heart rate up for 20 minutes makes your brain work better afterwards.
- Walk before a hard revision session. Especially in winter when daylight is short — getting outside helps.
- Walk between subjects. A 10-minute walk between Maths and Science clears your head and resets your focus.
- Don't stop your sport during exam season. It's tempting to think "I'll quit football until exams are over" to make more time for revision. Almost always a mistake. Sport is keeping your brain working.
What this looks like in practice
A normal day during exam season
- 8 hours of sleep (no negotiation)
- A real breakfast — not skipped, not just sugar
- Some kind of physical activity — sport, walking, cycling
- Real meals at normal times
- Water bottle filled, on the desk, used
- Caffeine, if any, before lunch
- Phone away from the bed
None of this is hard. But every single one of these makes revision genuinely more effective. Together they're worth more than an extra hour of revision.
The opposite of looking after yourself
The opposite is: late nights, skipping meals, no exercise, lots of caffeine, lots of sugar, lots of stress. This combination produces a brain that feels like it's working harder but is actually performing worse.
If you find yourself drifting into that pattern in exam season, it's a sign to course-correct, not a sign you're working hard. The students who score highest in their exams almost never do it on no sleep and energy drinks. They do it on the boring stuff.
Frequently asked questions
How much sleep does a teenager actually need?
NHS guidance recommends 8–10 hours for ages 14–17, and 7–9 hours for ages 18+. Teenagers genuinely need more sleep than adults — their bodies aren't being lazy when they want to lie in. Cutting sleep below this range to revise is counterproductive.
Is it true that breakfast affects exam performance?
Yes, measurably. Studies consistently show students who eat a balanced breakfast outperform those who skip it or eat sugary alternatives. The effect is strongest for working memory and sustained attention — both critical in exams.
My teenager won't go to bed earlier. What can I do?
Phones out of the bedroom is the single biggest factor. Late-night scrolling delays sleep onset by 30–60 minutes for most teenagers. If the phone leaves the bedroom an hour before bed, sleep timing usually improves naturally within a fortnight.
Are energy drinks really that bad during exam season?
For exam season, yes. The combination of caffeine and high sugar produces an alertness spike followed by a sharp crash 60–90 minutes later. The anxiety boost is also real. If a teenager genuinely needs caffeine, a single cup of coffee in the morning is much better than a 500ml energy drink in the afternoon.
A revision plan that respects rest
Most revision tools push children to revise more, longer, and more often. Learn with Fred is built around shorter, smarter sessions — about 35 minutes each, spread across the week with rest days built in. The goal is sustainable, evidence-backed revision that doesn't burn children out.
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