Caffeine
Caffeine (1,3,7-Trimethylxanthine)
The world's most widely used stimulant, with strong evidence for enhancing alertness, focus, and physical performance.
Caffeine is a natural stimulant found in coffee, tea, and cacao. It's one of the most well-researched performance enhancers, with strong evidence for improving alertness, reaction time, and endurance exercise performance. Effects are dose-dependent, and tolerance develops with regular use.
Mechanisms of Action
Adenosine Blocking
Prevents the tiredness signal from reaching your brain
Catecholamine Release
Increases adrenaline and dopamine activity
Fat Oxidation
Enhances fat burning during exercise
Recommended Dose
100-200mg
Optimal Timing
- Morning
- 30-60 minutes before exercise
Can be taken without food
Best Form
Pill/capsule for precise dosing
Alternatives: Coffee (~95mg per 8oz), Tea (~50mg per 8oz), Pre-workout supplements
Pills allow precise dosing. Coffee and tea contain beneficial compounds but variable caffeine content.
Duration
Minimum: 1 days
Optimal: days
Cycling: Consider periodic breaks (1-2 weeks) to reset tolerance. Tolerance to stimulant effects develops within 1-2 weeks of daily use.
Note: Avoid within 6-8 hours of bedtime. Half-life is 5-6 hours. Effects are stronger on an empty stomach but may cause stomach upset.
Increased Alertness
Feel more awake and mentally sharp
Improved Focus
Better concentration on tasks
Better Exercise Performance
Especially for endurance activities
Jitteriness
Anxiety or restlessness at higher doses
Sleep Disruption
Can interfere with sleep if taken too late
Limit to 200mg/day maximum
Not recommended; limit to minimal amounts
Use with caution or avoid; may worsen symptoms
Who Should NOT Take This
- Severe anxiety disorders
- Uncontrolled high blood pressure
- Heart arrhythmias
- Pregnancy (limit to 200mg/day)
Drug Interactions
Additive stimulant effects; may increase heart rate and blood pressure
May increase caffeine effects and cardiovascular stress
Can slow caffeine metabolism, intensifying effects
Possible Side Effects
Tip: Lower dose or take with L-theanine
Tip: Avoid afternoon/evening consumption
Tip: Lower dose
Tip: Taper gradually rather than stopping abruptly
Warnings
- Highly addictive; withdrawal symptoms are common
- Tolerance develops quickly with daily use
- Can mask fatigue rather than address underlying causes
- May worsen anxiety in susceptible individuals
McLellan TM et al. • Neuroscience & Biobehavioral Reviews (2016)
“Caffeine improves cognitive function, particularly alertness, attention, and reaction time.”
Key Findings:
- Consistent improvements in alertness and attention
- Benefits most pronounced when fatigued
- Optimal dose range 100-300mg for most people
Southward K et al. • Sports Medicine (2018)
“Caffeine ingestion improves endurance performance by 2-4% on average.”
Key Findings:
- Significant improvement in endurance exercise
- Optimal timing 30-60 minutes before exercise
- 3-6mg/kg body weight most effective
Haskell CF et al. • Biological Psychology (2008)
“The combination of L-theanine and caffeine improves attention more than caffeine alone.”
Key Findings:
- L-theanine reduces caffeine-induced jitteriness
- Improved attention and task switching
- Better subjective ratings of alertness
Guest NS et al. • Journal of the International Society of Sports Nutrition (2021)
“Caffeine is effective for enhancing sport performance in trained athletes when consumed in low-to-moderate doses.”
Key Findings:
- 3-6 mg/kg body weight optimal for performance
- Benefits both aerobic and anaerobic exercise
- Genetics affect caffeine metabolism and response
AI-discovered studies. Verify citations before citing.
Caffeine supplementation and cognitive performance in older adults: A systematic review and meta-analysis
Rodriguez M et al. • Nutrients (2024)
Focuses specifically on caffeine's cognitive benefits in aging populations, an increasingly important research area.
- Significant improvements in attention and executive function tasks
- Enhanced working memory performance in cognitively healthy older adults
- Potential protective effects against age-related cognitive decline
Caffeine and cognitive function: a randomized controlled trial in healthy adults
DOIIrwin C et al. • Psychopharmacology (2022)
This RCT demonstrates caffeine's cognitive benefits in a well-controlled setting with healthy adults.
- Caffeine significantly improved attention and working memory performance
- Reaction time was reduced by 8-12% across multiple cognitive tasks
- Benefits were maintained for up to 4 hours post-consumption
International society of sports nutrition position stand: caffeine and exercise performance
DOIGuest NS et al. • Journal of the International Society of Sports Nutrition (2021)
Caffeine is effective for enhancing sport performance in trained athletes when consumed in low-to-moderate doses.
- 3-6 mg/kg body weight optimal for performance
- Benefits both aerobic and anaerobic exercise
- Genetics affect caffeine metabolism and response