L-theanine and stress
What 2 graded rows on l-theanine agree on for stress, and where they differ. Counted side by side, never averaged.
Consensus finder Rows from the L-theanine page, reviewed Oct 21, 2026 How it decides
What the rows agree on
Each block and row is one graded row from the L-theanine page, with its PubMed record.
Your question
L-theanine and stress
2 rows · 60 peopleSplit. 1 row found an improvement and 1 had mixed results.
- DGrade D× 2
- Rows
- 2
- Trials
- 2
- People
- 60
What the rows share
From the rowsThe best-graded row, grade D, is a randomized trial of 30 people (2024) and reported mixed results.
The rows run from 30 people, published from 2019 to 2024: 2 single studies.
The rows
1 improved · 1 mixed- DGrade DStress, sleep quality and cognition over 4 weeks · Improved
Crossover RCT · n 30 · 2019 · Healthy adults (9 men, 21 women; mean age 48) without major psychiatric illness
200 mg/day · 4 weeks per period
Depression, trait-anxiety and sleep-quality (PSQI) scores decreased after L-theanine; sleep latency, sleep disturbance and use of sleep medication subscales fell compared with placebo. Verbal fluency and executive function scores improved.
- DGrade DPerceived stress and sleep in adults with moderate stress · Mixed
RCT · n 30 · 2024 · Healthy adults aged 18–65 with moderate stress (15 per group)
400 mg/day · 28 days
Perceived stress fell by about 18% with both L-theanine and placebo, and salivary cortisol did not differ between groups. L-theanine reduced light sleep versus placebo but also decreased time asleep at 28 days, and improved Stroop reaction time earlier than placebo.