Healthy habits for exam season: sleep, food and caffeine

How does sleep help you in exams?

Sleep is where the day's studying settles in. Adults aged 18 to 60 should get seven or more hours a night on a regular basis, according to the joint consensus of the American Academy of Sleep Medicine and the Sleep Research Society (Watson and colleagues, 2015). They stress that regularity and quality count too, not only the number of hours.

For exams specifically, the most useful finding comes from Okano and colleagues (2019), who gave sleep trackers to students in a college chemistry course. Better quality, longer and more consistent sleep went with better grades, and sleep measures accounted for nearly a quarter of the variation in results. The surprising part: sleep on the single night before a test showed no relationship with performance. Sleep over the previous week and month did.

That makes productive sleep a habit, not a last-minute fix:

• Same bedtime, same wake time, including weekends and the week of the exam.
• A wind-down cue: the last study session ends at a set time, screens go off, and tomorrow's first task goes on a sticky note so your head doesn't keep revising in bed.
• No all-nighters. They trade away the kind of sleep that's linked to better results, on a night that matters less than students think.

What should you eat during exam season?

Nothing exotic, just regular and real. Long study days go best on meals that keep your energy steady, not on a cycle of skipped meals and late-night sugar.

• A proper breakfast, especially before morning exams: oats, eggs, yoghurt, fruit, wholegrain toast.
• Balanced main meals: some protein (eggs, fish, chicken, beans, lentils, tofu), plenty of vegetables, and wholegrain carbs like brown rice, wholemeal pasta or potatoes.
• Smart snacks for study blocks: fruit, nuts, yoghurt, hummus with vegetables, or a slice of wholegrain toast instead of crisps and sweets.
• Water on your desk. Refill it at every break; it's an easy cue to stand up and move too.
• Eat at regular times. Tie meals to your study routine so a long session never runs straight through lunch.
• Keep exam day familiar. Eat what you normally eat; exam morning isn't the time to experiment.

A simple trick: cook or prep a few days' worth of easy meals at the start of the week. It removes daily decisions and keeps the healthy option the easy one.

Is caffeine good for studying?

Used well, yes. The European Food Safety Authority gave a favourable opinion to caffeine's effects on alertness and attention, based on a serving of around 75 mg, roughly a cup of coffee or a strong tea (as reported by NutraIngredients, 2015). That's why a morning coffee before a study session genuinely helps you focus.

The same authority's 2015 safety opinion says that for healthy adults who aren't pregnant, habitual intake up to 400 mg a day, and single doses up to 200 mg, don't raise safety concerns. It also notes that a dose of around 100 mg close to bedtime can delay sleep and shorten it in some people.

So the rule for exam season is about timing, not giving it up:

• Have it early: with breakfast or before your first study block, when it helps most.
• Stop by mid-afternoon, so it's out of the way by bedtime and your sleep stays productive.
• Stay moderate: two or three cups of coffee or tea across the morning is plenty. Energy drinks can pack a lot into one can, so check the label.
• On exam day, have your usual cup at your usual time; it's not the day to double up.

What does a healthy exam-season day look like?

• Wake at your usual time. Breakfast and a coffee, then your first study block.
• Mid-morning: fruit or yoghurt and a water refill between sessions.
• Lunch at a fixed time: protein, vegetables, wholegrain carbs. Last coffee or tea of the day.
• Afternoon study block, with a snack and water on the desk.
• Dinner, then a shorter evening session on your weakest topic.
• Wind down and the same bedtime as every night.

The study blocks themselves work best when they start with questions rather than rereading. Our study routine for exams shows how to build them, and how to make a revision timetable helps you plan the weeks. If you want questions ready to answer, Ace turns your own lecture slides, PDFs or YouTube lectures into practice questions and shows the line from your notes behind every answer.

Frequently asked questions

Sources

1. Watson, N. F. et al. (2015). Recommended amount of sleep for a healthy adult: A joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep, 38(6), 843–844. PDF
2. Okano, K., Kaczmarzyk, J. R., Dave, N., Gabrieli, J. D. E. & Grossman, J. C. (2019). Sleep quality, duration, and consistency are associated with better academic performance in college students. npj Science of Learning, 4, 16. PMC
3. EFSA Panel on Dietetic Products, Nutrition and Allergies (2015). Scientific opinion on the safety of caffeine. EFSA Journal, 13(5), 4102. EFSA explainer
4. Harrison-Dunn, A. (2015, March 6). Alert vs insomniac: EFSA says caffeine effect can be both good and bad. NutraIngredients. nutraingredients.com