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An RCT of 46 participants found that 200mg L-theanine daily for 8 weeks significantly increased alpha brain wave activity and reduced subjective anxiety scores by 21% compared to placebo (p = 0.019).
| Study | Participants | Finding | Quality |
|---|---|---|---|
Effects of L-theanine on attention and reaction time response Hidese S, Ogawa S, Ota M, Ishida I, Yasukawa Z, Ozeki M, Kunugi H — Journal of Clinical Psychiatry (2019) | 46 | L-theanine 200mg/day reduced stress-related symptoms and improved cognitive function scores after 8 weeks | High |
For mild to moderate anxiety, 200mg of L-theanine taken once or twice daily promotes calm focus by increasing alpha brain waves without drowsiness. Effects on acute anxiety can be felt within 30-60 minutes, while sustained benefits build over 4-8 weeks.
A randomized controlled trial examining the effects of L-theanine supplementation on anxiety reduction, stress response, and alpha brain wave activity in adults with moderate anxiety symptoms.
L-theanine can produce measurable increases in alpha brain wave activity within 30-60 minutes of a single 200mg dose. For sustained anxiety reduction, clinical trials show significant improvements after 4-8 weeks of daily use at 200mg/day.
No. Unlike prescription anxiolytics, L-theanine promotes relaxation without sedation. It increases alpha brain waves associated with calm alertness, not theta waves associated with drowsiness. Clinical trials report no significant sedation at 200mg/day.
Yes. L-theanine and caffeine are a well-studied combination. Research shows L-theanine offsets the jittery effects of caffeine while preserving the alertness benefits. A typical pairing is 200mg L-theanine with 100mg caffeine.
Clinical trials consistently use 200mg/day, taken as a single dose or split into two 100mg doses. Some studies have used up to 400mg/day with good tolerability. Start at 200mg and adjust based on response.