Caffeine
Caffeine blocks adenosine receptors to reduce perceived fatigue and increase alertness, focus, and exercise performance. Its main downsides — jitters, anxiety, and disrupted sleep — are why it is so often paired with L-theanine.
Benefits
Increases alertness and focus
StrongReliably reduces fatigue and improves reaction time and vigilance.
Enhances exercise performance
StrongA well-established ergogenic aid for endurance and power.
Pros & cons
Pros
- Powerful, fast-acting, inexpensive
- Strong evidence for focus and performance
Cons
- Tolerance builds quickly
- Can harm sleep and raise anxiety
Side effects
Jitters and anxiety
Higher doses can cause restlessness, racing heart, and anxiety.
Sleep disruption
Its long half-life can impair sleep if taken later in the day.
How to take it
Typical dose
50–200 mg per dose
Timing
Earlier in the day; avoid within 8–10 hours of bedtime
Common forms
Tip: Pairing with L-theanine smooths the stimulation. Cut off by early afternoon to protect sleep.
What the research says
Caffeine and cognitive performance
StrongImproves alertness, vigilance, and reaction time, especially when fatigued.
Caffeine as an ergogenic aid
StrongConsistently enhances endurance and high-intensity exercise performance.
How it connects
Relationships between Caffeine and other supplements in the matrix.
The classic nootropic stack: L-theanine smooths caffeine's jitters while preserving the focus boost.
Compare the pairingA debated, likely-minor interaction where caffeine may slightly reduce creatine's effects.
Compare the pairing