Short answer: Research shows low to moderate doses of caffeine (about 40-300mg) reliably improve alertness, attention and reaction time. The effects on memory and complex reasoning are less consistent. For most study sessions a small dose, around 30-75mg, is enough, and it's best kept to the first part of the day so it doesn't cut into sleep, which matters more for learning than caffeine does. One piece of Zuum Everyday Energy Gum has 30mg of caffeine.
Caffeine is the most popular study aid in the world. Used well, it helps you stay switched on through a long block of reading or revision. Used badly, it leaves you jittery at 11pm with a pile of notes you can't remember. Here's what the research actually says.
What caffeine does (and doesn't do) for study
The most thorough review of the area is a 2016 review of caffeine's effects on cognitive and physical performance by researchers working with the US military. It found:
- Alertness, vigilance, attention and reaction time improve after low (about 40mg) to moderate (about 300mg) doses of caffeine.
- Effects on memory and higher-level thinking are less consistent. Some studies find a benefit, many don't.
- Caffeine is most useful when you're tired. Repeated doses helped people hold their performance when sleep was restricted.
In practice, that means caffeine is good at keeping you awake and on task. It won't make you smarter, and it can't replace understanding the material.
A little caffeine goes a long way
You don't need a big dose to feel the difference. In a study of low doses of caffeine, as little as 12.5mg improved attention and mood, and the effects at 12.5-100mg were broadly similar. More caffeine didn't mean more benefit.
That matters for students, because higher doses bring the side effects that hurt study: jitters, a racing heart, anxiety and trouble sleeping. We cover this in more detail in low dose caffeine and focus.
| Caffeine source | Typical caffeine |
|---|---|
| 1 piece of Zuum Everyday Energy Gum | 30mg |
| Can of cola (375ml) | About 36mg |
| Cup of black tea (220ml) | About 50mg |
| 1 serve (2 pieces) of Zuum Everyday Energy Gum | 60mg |
| Energy drink (250ml can) | About 80mg |
| Instant coffee (1 teaspoon) | About 80mg |
| Espresso coffee (50ml) | About 145mg |
Coffee varies the most. A large café coffee with a double shot can easily be well over 150mg, which is a lot for a quiet afternoon in the library. See how much caffeine is in coffee, tea and energy drinks for the full list.
Protect your sleep: it's where learning sticks
Sleep is when your brain consolidates what you learned during the day. Cutting it short to study more, or because caffeine kept you awake, usually backfires.
In a sleep study, 400mg of caffeine taken 6 hours before bed still significantly disrupted sleep, cutting total sleep time by more than an hour. Caffeine's half-life is typically 3-7 hours, so a mid-afternoon coffee can still be working at bedtime.
A simple rule: keep caffeine to the morning and early afternoon, and stop at least 6 hours before you plan to sleep. If you need a lift later in the day, keep the dose small.
A simple caffeine plan for a study day
Morning block
- Your usual coffee or tea with breakfast is fine.
- If you'd rather skip the coffee run, 1-2 pieces of Zuum Everyday Energy Gum (30-60mg) at the start of your session.
After lunch
- This is when the afternoon slump hits. Get up, walk, get some daylight.
- If you still need it, 1 piece of gum (30mg). A small dose is less likely to affect your sleep.
Evening
- Skip caffeine. Review notes instead of learning new material, and get to bed at a regular time.
Exam day
- Have what you normally have. Exam morning isn't the day to try a big dose for the first time.
- Gum is handy here: it's quick, and you don't need to drink a whole coffee before you walk into the exam room. Check your exam rules first, as some exam halls don't allow food or gum.
Common mistakes
- All-nighters fuelled by energy drinks. You'll trade a few extra hours of study for worse memory and a foggy exam.
- Stacking doses. Coffee, then an energy drink, then a pre-workout adds up fast. Australia's food regulator recommends adults stay under 400mg a day.
- Using caffeine to cover for no sleep, night after night. Caffeine masks tiredness, it doesn't fix it.
- Big doses when you're anxious. If exams already make you nervous, high caffeine can make it worse.
How much is too much?
Food Standards Australia New Zealand (FSANZ) recommends healthy adults have no more than 400mg of caffeine a day, and no more than 200mg in a single serve. For people who are pregnant or breastfeeding the limit is 200mg a day, and under-18s should have no more than 3mg per kg of body weight in a single serve. If you have a heart condition or anxiety, or take medication, check with your doctor first.
Frequently asked questions
Does caffeine help you study?
Caffeine improves alertness, attention and reaction time, which helps you stay on task during a long study session. Its effects on memory are less consistent, and it can't replace a good night's sleep.
How much caffeine should I have to study?
Research shows benefits for attention from as little as 12.5-40mg, and little extra benefit at higher doses for most people. A small dose like 30-75mg is a sensible place to start.
When should I stop having caffeine before bed?
At least 6 hours before. In one study, caffeine taken 6 hours before bed still cut sleep by more than an hour.
Is caffeine gum good for studying?
Caffeine gum is a convenient way to get a small, measured dose without a drink. One piece of Zuum Everyday Energy Gum has 30mg of caffeine, so you can have one piece at a time and stop when you've had enough.
Should I use caffeine for an all-nighter?
It's better not to pull an all-nighter at all. Sleep helps your brain store what you've learned, so a full night's sleep before an exam usually beats extra hours of study.
The bottom line
Caffeine can help you stay alert and focused while you study, and a small dose does most of the work. Keep it to the morning and early afternoon, protect your sleep, and don't rely on it to cover for all-nighters. If you want a measured, low-dose option, Zuum Everyday Energy Gum has 30mg per piece, with guarana and B vitamins.
Read the study: McLellan TM, Caldwell JA, Lieberman HR (2016), A review of caffeine's effects on cognitive, physical and occupational performance, Neuroscience & Biobehavioral Reviews 71:294-312. Abstract on PubMed.
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