Caffeine and performance: studied doses, safety and sleep
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What ISSN says
The 2021 ISSN position reports acute benefits in many, not all, studies. Aerobic endurance has some of the most consistent findings, but magnitude varies between people. A frequently studied range is 3–6 mg/kg; the minimum effective dose remains uncertain and may be around 2 mg/kg. Very high doses, such as 9 mg/kg, increase adverse effects without being required for benefit.1
The most common timing in studies is about 60 minutes before exercise, but form matters: caffeinated gum does not necessarily have the same timing as a capsule. This is not a reason to take more products if an effect does not feel immediate.
Performance and safety are different questions
| Source and context | Reported quantity | How to read it |
|---|---|---|
| ISSN, performance studies | Often 3–6 mg/kg | Research range, not an individual safety guarantee |
| EFSA, healthy adults | Up to 200 mg as a single dose from all sources | No safety concerns in assessed conditions, also before intense exercise in normal environmental conditions |
| EFSA, healthy non-pregnant adults | Up to 400 mg spread throughout the day | Not a target or guarantee for every person |
| EFSA, sleep | Even 100 mg near bedtime | May affect sleep duration and patterns in some adults |
EFSA’s assessment does not cover diseases or medicine interactions. Healthy-adult references should not automatically be extended to minors, pregnancy or breastfeeding, or people with cardiac conditions, anxiety or other conditions. These require discussion with a healthcare professional, not a table calculation.2
Calculation examples, not recommended doses
| Hypothetical weight | 2 mg/kg | 3 mg/kg | 6 mg/kg |
|---|---|---|---|
| 60 kg | 120 mg | 180 mg | 360 mg |
| 70 kg | 140 mg | 210 mg | 420 mg |
| 80 kg | 160 mg | 240 mg | 480 mg |
At 70 kg, 3 mg/kg is 210 mg, already above EFSA’s 200-mg single-dose reference. Six mg/kg is 420 mg, above its 400-mg daily reference before counting coffee or tea. This does not make 201 mg a toxicity threshold: it means performance ranges do not automatically authorise any intake.12
A hypothetical label example: an 80-mg serving, a 100-mg serving and a 50-mg gel total 230 mg. Count all sources rather than assuming every espresso has a fixed dose. EFSA notes variation by preparation, beans and serving size; a coffee count is not a precise unit.2
Sleep, stomach and individual response
Anxiety, palpitations, gastrointestinal problems and disturbed sleep can offset the intended benefit. ISSN describes variability involving metabolism and individual response. There is no single cutoff time for everyone. For evening races, consider sleep costs alongside potential benefit, not afterwards.12
Caffeine does not replace recovery, carbohydrate or hydration. ISSN considers effects under sleep deprivation, but this does not establish that caffeine removes the need to sleep.
Read a product without stacking blindly
- Check milligrams per serving and servings per packet. One gel is not a standard dose.
- Add coffee, tea, drinks and other supplements already consumed.
- Do not automatically add a mid-race caffeinated gel after a pre-start dose: the total is part of the decision.
- Do not try a new product on race day. Past tolerance does not guarantee no adverse effects.
- If symptoms, medical conditions or medicines are involved, do not use the table to decide alone.
Sources
- Guest NS et al. International society of sports nutrition position stand: caffeine and exercise performance, 2021. PMC.
- EFSA. Caffeine, topic page and FAQ on the 2015 safety assessment. EFSA.
Sources consulted on 29 October 2026. Hypothetical examples, not prescriptions.