Research · Randomized controlled trial
Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial
What it found
L-theanine lowered the overall PSQI score and improved sleep-latency, sleep-disturbance, and sleep-medication subscales versus placebo.
- Design
- Randomized controlled trial
- Year
- 2019
- Sample size
- 30
- Population
- healthy adults (mean age ~48), crossover
- Intervention
- L-theanine 200 mg/day for 4 weeks vs placebo
- Outcome
- Pittsburgh Sleep Quality Index and stress/cognition
- Journal
- Nutrients
Citation last checked 2026-06-21.