L-theanine supplementation at 200-450 mg/day supports healthy sleep in adults
A systematic review of 13 trials (n=550) found that L-theanine at 200-450 mg/day appears safe and effective for improving sleep in adults. Beneficial effects were reported on sleep latency, maintenance, efficiency, perceived satisfaction, and feelings of refreshment upon waking.
This article is automatically generated from the structured evidence profile behind the claim above. Scores reflect the quality and quantity of available research, not clinical advice.
L-theanine supplementation at 200-450 mg/day supports healthy sleep in adults The current body of evidence comprises 1 study. EvidenceHub rates the overall confidence at 32/100 (low).
The Claim
L-theanine supplementation at 200-450 mg/day supports healthy sleep in adults
This conclusion is most relevant to: Adults (general population, not specifically clinical insomnia patients).
What the Research Shows
The conclusion draws on 1 linked study. Highlights from the cited literature:
- ▸Examining the effect of L-theanine on sleep: a systematic review of dietary supplementation trials. (Nutritional neuroscience, 2026) —
How It Works
The proposed biological pathway:
- ▸L-theanine is a non-protein amino acid from tea leaves
- ▸Previous studies show it aids relaxation without sedation
- ▸Pre-clinical studies suggest calming effects
- ▸Result: Supports healthy sleep in adults
Who Might Benefit
Evidence fit by population:
- ▸Adults (general population, not specifically clinical insomnia patients)
Recommended Dose
200-450 mg/day
Limitations & Caveats
Important context when interpreting this evidence:
- ▸Only 13 trials with small total sample size (n=550)
- ▸No high-quality trials specifically in clinical insomnia populations
- ▸Limited use of objective sleep measures in some trials
Frequently Asked Questions
What is the recommended dose of L-theanine for sleep?▼
Based on this review, 200-450 mg/day appears safe and effective for supporting healthy sleep in adults.
Does L-theanine cause sedation or affect cognitive function?▼
No, previous studies report that L-theanine aids relaxation without causing sedation or adversely impacting cognitive function.
What sleep outcomes does L-theanine improve?▼
It improves sleep latency, maintenance, efficiency, perceived sleep satisfaction, and feelings of refreshment and recovery on waking.
Is L-theanine effective for people with clinical insomnia?▼
The review did not specifically study clinical insomnia patients; further high-quality trials in that population are needed.
References
- 1.Cotter J, Caddick CE, Harper JL, Ebajemito JK. “Examining the effect of L-theanine on sleep: a systematic review of dietary supplementation trials..” Nutritional neuroscience, 2026. PMID: 41176609 DOI: 10.1080/1028415X.2025.2556925