L-Theanine
The amino acid in green tea that creates calm focus. Fast-acting (30–60 min), non-sedating, takes the jitter out of caffeine.
Multiple RCTs support acute anxiety reduction, improved sleep quality, and synergy with caffeine for attention and reaction time. Subjective stress reduction within hours. Sleep effects: within nights. One of the cleanest, safest supplements in this reference.
L-Theanine is a non-protein amino acid found almost exclusively in tea. It crosses the blood-brain barrier easily and increases alpha brainwave activity — the 'awake but relaxed' state associated with meditation and easy focus. Mechanistically it boosts GABA, serotonin, and dopamine while damping excitatory glutamate. The result is calm without sedation. It pairs famously with caffeine: 200 mg theanine + 100 mg caffeine produces the cleanest 'flow state' stack in the supplement world, taking the edge off caffeine's jitter while preserving the focus.
- Form
- Plain L-theanine — usually 100 or 200 mg capsules. Suntheanine is the patented, well-studied form. Free-form powder works too.
- Dose
- 100–200 mg as needed (acute). 200–400 mg pre-bed for sleep support.
- Timing
- Anytime — AM with coffee for calm focus, PM 30–60 min before bed for sleep. Onset within 30–60 min of a single dose.
- Schedule
- Daily or as-needed. No tolerance build-up, no withdrawal.
- Side effects
- Almost none. Occasionally mild headache or dizziness at very high doses.
- Interactions
- Mild blood-pressure lowering (usually beneficial). Sedatives — additive at sleep-doses.
- Contraindications
- None significant. Caution if on blood pressure medication (additive lowering).
- Lab markers
- Not tested.
- Food sources
- Green tea, white tea, black tea. A cup of green tea has 25–60 mg L-theanine. Matcha is the highest natural source (~30–40 mg per gram of powder). Reaching therapeutic doses (200 mg) from tea alone requires 4–8 cups.
Pairs with
Caffeine — the classic stack (2:1 theanine:caffeine ratio for most users). Magnesium glycinate for sleep. Apigenin and glycine for a layered sleep protocol. Ashwagandha for chronic stress.
within Amino acids & derivatives