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Evidence-Based Supplement Research

Evidence-Based Supplement Research

L-Theanine and Improved Sleep Quality

Doses used in studies

mg/day: 200 (median 200, IQR 200–200) — 1 study

Time to effect

Median: 4 weeks · IQR 4 weeks–4 weeks · Range 4 weeks–4 weeks — Reported in 1 of 2 studies

2 of 2 papersPopulation:

Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial.
- 2019-10-03
- RCT · n = 30
- Nutrients 11(10)
- - Shinsuke Hidese
  - Shintaro Ogawa
  - Miho Ota
  - Ikki Ishida
  - Zenta Yasukawa
  - Makoto Ozeki
  - Hiroshi Kunugi
- PubMed: 31623400
- DOI: 10.3390/nu11102362
8 Insights on
- Improved Sleep Quality
- High evidence
- Rigorous Journal
- Adults
Pittsburgh Sleep Quality Index (PSQI) scores decreased after L-theanine administration (p = 0.013)
Effect
Beneficial
Effect size
Moderate
Significant
Yes
Dose
200 mg/day
The effects of L-theanine consumption on sleep outcomes: A systematic review and meta-analysis.
- 2025-06
- Meta-Analysis · n = 897
- Sleep medicine reviews 81
- - Amanda Bulman
  - Nathan M D'Cunha
  - Wolfgang Marx
  - Murray Turner
  - Andrew McKune
  - Nenad Naumovski
- PubMed: 40056718
- DOI: 10.1016/j.smrv.2025.102076
3 Insights on
- Improved Sleep Quality
- High evidence
- Mixed
overall subjective sleep quality score (SMD = 0.43, 95 % CI [0.04, 0.83], p = 0.03; n = 12 studies)
Effect
Beneficial
Effect size
Moderate
Significant
Yes