L-Theanine
Content by: OpenSupplement Editorial Team | Medical review: pending | Last updated: April 13, 2026
TL;DR
Unique amino acid found in green tea leaves
High evidence for promoting 'relaxed alertness' without sedation
Moderate evidence for improving sleep quality when paired with Magnesium
Synergizes perfectly with Caffeine to prevent 'jitters'
Excellent safety profile
Affordable: ~$8-15/month
Best for: Anxiety, focus, sleep onset
What it is
L-Theanine is a non-protein amino acid that crosses the blood-brain barrier. It promotes the production of Alpha brain waves, which are associated with a state of 'calm focus.' It increases levels of GABA, serotonin, and dopamine in the brain, providing a gentle mood-stabilizing effect.
What the research says
No direct tinnitus trials. Theoretical benefit via stress/anxiety reduction, which modulates tinnitus perception. Anecdotal reports in tinnitus communities.
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L-Theanine on Amazon
Safety
Extremely safe. There is no known toxicity. It does not cause dependency or morning grogginess.
Interactions
- Blood Pressure Meds: May have a mild additive effect, lowering blood pressure slightly.
Dosing
For Focus: 100-200 mg (usually paired with caffeine). For Sleep/Anxiety: 200-400 mg before bed.
Cost
Inexpensive. $8-15 per month.
The bottom line
Theanine is the perfect 'modern life' supplement. It takes the edge off stress and caffeine without dulling your senses.
References
- Hidese S, Ogawa S, Ota M, et al. Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults: a randomized controlled trial. Nutrients. 2019;11(10):2362.
- Rao TP, Ozeki M, Juneja LR. In search of a safe natural sleep aid. J Am Coll Nutr. 2015;34(5):436-47.
Sources for this page include published meta-analyses, systematic reviews, and NIH dietary supplement fact sheets. All claims reflect the evidence as of early 2026.
This is not medical advice. Consult your healthcare provider before starting any supplement, especially if you take medications.