howtosupplement
Mood/Sleep/Cognition

L-Theanine

Tea amino acid that promotes calm focus and may improve stress, sleep, and attention in adults under mental load.

L-Theanine

L-Theanine

64
score
B
evidence
Safe
risk
Quick Take

Useful for calm focus or evening wind-down; effects are real but usually modest, not dramatic.

L-theanine is a non-protein amino acid found mainly in green and black tea, with smaller amounts in some mushrooms. It crosses the blood-brain barrier and modulates glutamate signaling while increasing alpha-wave activity linked to relaxed wakefulness. Best-supported uses are lowering perceived stress, modestly improving sleep quality, and improving attention when paired with caffeine. It tends to help most in stressed adults and people who want smoother, calmer stimulation.

Proven Benefits

01
Reduces stress and anxiety
02
Improves sleep quality
03
May improve attention with caffeine
04
May reduce mental fatigue
05
May reduce caffeine jitters

Protocol

Amount
100-200 mg
Frequency
Once or twice daily
When
30-60 minutes before a stressful task, with caffeine, or before bed; with or without food.

Onset Time

30-60 min for calm/focus; 1-2 weeks for sleep with daily use

Who Should Consider

Adults with stress-related tension
People sensitive to caffeine jitters
Tea or coffee drinkers wanting calmer focus
Adults with mild stress-related sleep issues
Students or desk workers under mental load

Food Sources

  • Green tea (~8-25 mg per cup)
  • Black tea (~5-20 mg per cup)
  • Matcha (~20-40 mg per 2 g serving, variable)
  • Shade-grown teas like gyokuro (~20-50 mg per cup, variable)

How It Works

L-theanine crosses into the brain and interacts with glutamate pathways, which can reduce mental overstimulation. It also increases alpha-wave activity associated with relaxed alertness and appears to influence GABA, dopamine, and stress-response signaling.

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