Skip to content
DE
Other

Caffeine

Caffeine is a natural stimulant of the methylxanthine class found in coffee beans, tea leaves, cocoa and guarana.

Also listed as Coffee extract, Tea extract, 1 3 7-Trimethylxanthine, Caffeine Anhydrous

CognitionEnergyStress & Mood

What it is studied for

The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.

Mental EnergyCognitionStrongA3 studies
Focus And AttentionCognitionStrongA3 studies
Physical EnergyEnergyStrongA3 studies
Mental SpeedCognitionModerateA3 studies
MemoryCognitionSmallB3 studies
Acute StressStress & MoodSmallCNo linked study
Every rating with its studiesGrouped by health goal, with the publications behind each rating

What does caffeine actually improve?

Caffeine most reliably improves alertness, attention and reaction time. Its effects on memory and complex decision-making are less consistent, so feeling more awake is not the same as performing every mental task better. 1

How does it keep you awake?

Caffeine blocks adenosine receptors, interfering with signals involved in sleep pressure. Its stimulating effect can therefore come with a cost to later sleep. 1 2

Key studies

The most recent publications linked to Caffeine's ratings.

Examining the effects of caffeine during an auditory attention task2024Mental Performance and Sport: Caffeine and Co-consumed Bioactive Ingredients2022How does caffeine influence memory? Drug, experimental, and demographic factors2021Caffeine effects on systemic metabolism, oxidative-inflammatory pathways, and exercise performance.2020Effects of caffeine supplementation on physical performance and mood dimensions in elite and trained-recreational athletes2020
All 12 studiesEvery publication linked to Caffeine

Why people take it

Energy25.1%
Cognition20.5%
Fitness20.4%
Weight Management12.8%
Essential Health9.1%
Stress & Mood4.7%

SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.

Questions people ask

Is 400 mg a daily goal?

No. It is a safety assessment for healthy adults, not a recommended intake. 3

Can caffeine affect sleep below that amount?

Yes. EFSA notes that even 100 mg near bedtime can affect some adults. 3

Is more better for sport?

Very high doses increase side effects and are not needed for a performance benefit. 4

How can I cut back?

FDA suggests reducing gradually because withdrawal can be unpleasant. 5

Is there one bedtime cutoff for everyone?

No universal cutoff follows from the cited sleep analysis; both dose and timing mattered. 2

Sources

  4. International society of sports nutrition position stand: caffeine and exercise performance Journal of the International Society of Sports Nutrition, 2021

Further reading

Illustration for Caffeine.GuideMushroom coffee: effects, caffeine and risksWhat is proven about mushroom coffee? Caffeine, lion's mane, cordyceps, reishi and chaga compared, with study doses, limits and kidney risks.Read the article