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Evidence-Based Supplement Research

Evidence-Based Supplement Research

L-Theanine and Improved Sleep Satisfaction

Doses used in studies

mg/day: 50–900 (median 575, IQR 150–900) — 2 studies

Time to effect

Median: 10 weeks · IQR 10 weeks–10 weeks · Range 10 weeks–10 weeks — Reported in 1 of 2 studies

Safety in these studies

Overall tolerabilityReported
Based on the current evidence, supplementation with 200-450 mg/day of L-theanine appears to be a safe and effective way to support healthy sleep in adults.
from: Examining the effect of L-theanine on sleep: a systematic review of dietary supplementatio

2 of 2 papersPopulation:

L-theanine in the adjunctive treatment of generalized anxiety disorder: A double-blind, randomised, placebo-controlled trial.
- 2019-03
- RCT · n = 46
- Journal of psychiatric research 110
- - Jerome Sarris
  - Gerard J Byrne
  - Lachlan Cribb
  - Georgina Oliver
  - Jenifer Murphy
  - Patricia Macdonald
  - Sonia Nazareth
  - Diana Karamacoska
  - Samantha Galea
  - Anika Short
  - Carolyn Ee
  - Yoann Birling
  - Ranjit Menon
  - Chee H Ng
- PubMed: 30580081
- DOI: 10.1016/j.jpsychires.2018.12.014
7 Insights on
- Improved Sleep Satisfaction
- High evidence
- Clinical
LT treated participants reported greater self-reported sleep satisfaction than placebo (ISI item 4; p = 0.015)
Effect
Beneficial
Effect size
Small
Significant
Yes
Dose
450-900 mg
Examining the effect of L-theanine on sleep: a systematic review of dietary supplementation trials.
- 2025-11
- Systematic Review
- Nutritional neuroscience 29(2)
- - Jack Cotter
  - Charlotte E Caddick
  - Jessica L Harper
  - James K Ebajemito
- PubMed: 41176609
- DOI: 10.1080/1028415x.2025.2556925
6 Insights on
- Improved Sleep Satisfaction
- High evidence
- Adults
beneficial effects were reported on both objective and participant-reported outcomes, including measures linked to sleep latency, maintenance and efficiency, perceived sleep satisfaction and feelings of refreshment and recovery on waking.
Effect
Beneficial
Effect size
Small
Significant
Yes
Dose
50-900 mg/day