StackTerminal.Health

BETA

Caffeine

Acute performance & alertness benefits; individual sensitivity varies; timing matters for sleep.

performancefocusalertnessendurance
Evidence last reviewed: 04 Apr 2026
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Trade-offs & context
Known concerns, timing considerations, & interactions
Sleep

Impairs sleep onset and deep sleep if consumed within 8–10 hours of bedtime

Tolerance

Tolerance develops within 1–2 weeks of daily use, reducing efficacy

Neural

Withdrawal: headache and fatigue on cessation after sustained daily use

Cardiovascular

Elevated heart rate, anxiety, jitteriness — individual sensitivity varies widely

Context: doses >400mg

Dot colour: High concern  Moderate   Low / note
Biomarkers studied
Outcomes directly measured across the evidence records below
Sleep
Sleep LatencySleep DurationSleep Efficiency
Cognitive
Reaction TimeFocus / Attention
Performance
Aerobic CapacityMuscle Strength (1RM)Power Output
Evidence
3 records
Endurance & sport performance
Athletes and active adultsISSN Position Stand (systematic review)
PUBMEDHigh

Strong evidence that 3–6 mg/kg caffeine improves endurance, strength, & power; benefits consistent but moderated by genetics & habituation.

Dose: 200 mgDuration: Acute (single dose)
CYP1A2 & ADORA2A genotypes influence individual response.
Cognitive performance (attention, reaction time)
Healthy adults (31 trials, n=1,455)Systematic review & meta-analysis
PUBMEDHigh

Caffeine significantly improves reaction time (g=0.28) & accuracy (g=0.27) on attention tasks; dose ≥200 mg shows larger effects.

Dose: 200 mgDuration: Acute
Benefits are acute; tolerance develops with daily use.
Sleep disruption (safety warning)
Healthy adultsSystematic review & meta-analysis
PUBMEDHigh

Caffeine prolongs sleep latency, reduces total sleep time & efficiency; clinically meaningful disruption occurs with 400 mg within 8–12 h of bedtime.

Dose: 200 mgDuration: Acute
Avoid caffeine within 6–8 h of intended sleep time when sleep is a priority.
Forms
Caffeine anhydrous
Predictable dose; common pre-workout.
Coffee
Variable caffeine; other compounds present.

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