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Amino acid from tea that promotes relaxation by increasing alpha brain-wave activity and modulating GABA, dopamine, and serotonin without sedation.
Better characterized for relaxation/anxiety than for sleep itself. In a small placebo-controlled RCT (30 healthy adults), 200 mg/day for 4 weeks lowered PSQI sleep scores and anxiety/depression measures, with improvements in sleep latency and sleep-disturbance subscales. A 2025 systematic review (19 trials, ~897 participants) found mainly subjective improvements in sleep latency and daytime dysfunction. Effects are modest, and many positive trials combine L-theanine with casein peptides or other actives.
200 mg/day (range ~200-400 mg), often taken in the evening.
Educational summary of doses studied — not a recommendation. Talk to a clinician before starting any supplement.
Educational summary of published research, checked against primary sources and linked inline. Not medical advice; supplements are not FDA-evaluated to treat disease. See our editorial policy.