L-テアニン ： 不眠症
A合計916名の参加者を対象とした16件の研究（メタアナリシス4件、RCT 4件を含む）に基づく。16件中11件の研究で肯定的な効果が示されている。
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A
結論
L-theanine is well-supported by research as a supplement that may help improve sleep quality, especially for people who struggle with a busy mind at bedtime.
- 11 out of 16 studies show positive effects, including 4 RCTs and 4 meta-analyses
- A 2026 systematic review confirmed L-theanine's benefits for sleep
- Shown to be comparable to melatonin for sleep improvement in a 2024 cancer patient trial
- Works by enhancing GABA activity and reducing mental arousal without next-day grogginess
Key Study Findings
systematic review
n=550
Double-blind
Examining the effect of L-theanine on sleep: a systematic review of dietary supplementation trials.
Dose: L-theanine 50-900 mg/day; effective range 200-450 mg/day
vs: Placebo
効果: Beneficial effects on sleep latency, maintenance, efficiency; improved perceived sleep satisfaction
None
RCT
n=120
2 weeks
Double-blind
Comparison Between Efficacy of Oral Melatonin and Oral L-theanine in Improving Sleep in Cancer Patients …
Dose: Melatonin 3 mg or L-theanine 200 mg taken 2h before bedtime for 14 days
vs: Placebo
効果: None
p<0.005
narrative review
Herbal and Natural Supplements for Improving Sleep: A Literature Review.
Dose: varies by supplement
vs: Placebo
効果: None
None
RCT
n=40
8 weeks
Double-blind
Dietary supplementation with Lactium and L-theanine alleviates sleep disturbance in adults: a double-blind, randomized, placebo-controlled …
Dose: None
vs: Placebo
効果: None
None
animal study (preclinical)
Protective effects of a probiotic-fermented germinated grain complex on neurotransmitters and sleep quality in sleep-deprived …
Dose: 7 L fermentation product; GABA 12.555 µmol/L, L-theanine 0.471 mg/mL
vs: Placebo
効果: None
p < 0.0001 (sleep duration KEY
systematic_review
The Role of Supplements and Over-the-Counter Products to Improve Sleep in Children: A Systematic Review.
Dose: iron, 5-hydroxytryptophan (5-HTP), theanine, antihistamines (OTC supplements)
vs: Placebo
効果: None
None
Key Statistics
16
研究数
916
参加者数
↑
Positive
A
グレード
Referenced Papers
Examining the effect of L-theanine on sleep: a systematic review of dietary supplementation trials.
Systematic Review
Nutritional neuroscience
2026
Psychiatry investigation
2024
24 件の引用
Frontiers in microbiology
2024
13 件の引用
Frontiers in nutrition
2024
5 件の引用
Indian journal of …
2024
3 件の引用
The Role of Supplements and Over-the-Counter Products to Improve Sleep in Children: A Systematic Review.
Systematic Review
International journal of …
2023
14 件の引用
Nutrients
2023
6 件の引用
Child and adolescent …
2023
5 件の引用
Medicinal herbs for the treatment of anxiety: A systematic review and network meta-analysis.
Meta-Analysis
Pharmacological research
2022
51 件の引用
Food research international …
2022
46 件の引用
Pharmaceutical biology
2019
134 件の引用
Journal of psychiatric …
2019
46 件の引用
Paediatric drugs
2017
26 件の引用
To sleep or not to sleep: a systematic review of the literature of pharmacological treatments of insomnia in children and …
Systematic Review
Journal of child …
2013
56 件の引用
Pharmacology, biochemistry, and …
2012
51 件の引用
Medical science monitor …
2009
85 件の引用
Dosage & Usage
mg = milligrams · mcg = micrograms (1,000× smaller) · IU = International Units
一般的な使用量
- sleep:
- 200-400 mg, 30-60 min before bed
上限量： Not established; generally safe up to 900 mg/day
研究で検討された用量
| 用量 | 期間 | 効果 | N |
|---|---|---|---|
| L-theanine 50-900 mg/day; effective range 200-450 mg/day | -- | Positive | 550 |
| Melatonin 3 mg or L-theanine 200 mg taken 2h before bedtime for 14 days | 2 weeks | Positive | 120 |
| varies by supplement | -- | Positive | -- |
| None | 8 weeks | Positive | 40 |
| 7 L fermentation product; GABA 12.555 µmol/L, L-theanine 0.471 mg/mL | -- | Positive | -- |
| iron, 5-hydroxytryptophan (5-HTP), theanine, antihistamines (OTC supplements) | -- | Mixed | -- |
| l-theanine 200 mg/day, GABA 111.1 mg/day, AVLE 50 mg/day, l-serine 300 mg/day | -- | Positive | 160 |
| None | -- | Positive | -- |
推奨摂取タイミング： 30-60 minutes before bed
Safety & Side Effects
報告されている副作用
- ⚠ Headache
- ⚠ Dizziness
- ⚠ GI discomfort
既知の相互作用
- ● Blood pressure medications — L-theanine may lower blood pressure
- ● Stimulants (caffeine) — may partially counteract stimulant effects
- ● Sedatives — potential additive calming effects
耐容上限摂取量： Not established; generally safe up to 900 mg/day
サプリメントの摂取を開始する前に、必ず医療専門家にご相談ください。
Frequently Asked Questions
Does L-テアニン help with 不眠症?
Based on 16 studies with 916 participants, there is strong evidence from multiple clinical trials that L-テアニン may support 不眠症 management. Our evidence grade is A (Strong Evidence).
How much L-テアニン should I take for 不眠症?
Studies have used various dosages. A commonly studied range is 200-400 mg, 30-60 min before bed. Always consult your healthcare provider before starting any supplement regimen.
Are there side effects of L-テアニン?
Reported side effects may include Headache, Dizziness, GI discomfort. Most side effects are mild and dose-dependent. Consult your doctor if you experience any adverse reactions.
How strong is the evidence for L-テアニン and 不眠症?
We rate the evidence as Grade A (Strong Evidence). This rating is based on 16 peer-reviewed studies with 916 total participants. The overall direction of effect is positive.
Related Evidence
L-テアニン 他の症状・状態について
FDAに関する免責事項: これらの記述は米国食品医薬品局（FDA）による評価を受けていません。本ウェブサイトの製品および情報は、疾病の診断、治療、治癒、または予防を目的としたものではありません。表示されているエビデンスグレードは、公開された査読済み研究の分析に基づいており、医療上の助言を構成するものではありません。サプリメントの摂取を開始する前に、必ず医療専門家にご相談ください。