L-テアニン：入眠困難

A エビデンス複数の大規模臨床試験が一貫して有意な効果を示しています。

合計590名の参加者を対象とした4件の研究（メタアナリシス2件、RCT 1件を含む）に基づく。4件中3件の研究で肯定的な効果が示されている。

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結論

Research suggests L-theanine may help you fall asleep faster, with strong supporting evidence from systematic reviews and clinical trials.

3 out of 4 studies show positive effects, earning a Grade A evidence rating
A 2026 systematic review confirmed L-theanine's benefits for sleep onset
Combining L-theanine with GABA may enhance the sleep-onset effect
Benefits demonstrated in a 2024 double-blind, placebo-controlled clinical trial

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=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

In Vitro

GABA and l-theanine mixture decreases sleep latency and improves NREM sleep.

Dose: GABA/l-theanine 100/20 mg/kg vs: Placebo 効果: 20.7-14.9% decrease in sleep latency; 87.3-26.8% increase in sleep duration; REM +99.6%; NREM +20.6%

Systematic Review

To sleep or not to sleep: a systematic review of the literature of pharmacological treatments …

Dose: Zolpidem, L-theanine, clonidine, melatonin (doses not specified in abstract) vs: Placebo 効果: Melatonin: reduced sleep latency, higher total sleep time, higher sleep efficiency; Clonidine: reduc None

Key Statistics

研究数

590

参加者数

↑

Positive

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

Dietary supplementation with Lactium and L-theanine alleviates sleep disturbance in adults: a double-blind, randomized, placebo-controlled clinical study. Other

Frontiers in nutrition 2024 5 件の引用

GABA and l-theanine mixture decreases sleep latency and improves NREM sleep. Other

Pharmaceutical biology 2019 134 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

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
None	8 weeks	Positive	40
GABA/l-theanine 100/20 mg/kg	--	Positive	--
Zolpidem, L-theanine, clonidine, melatonin (doses not specified in abstract)	--	Mixed	--

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 入眠困難?

Based on 4 studies with 590 participants, there is strong evidence from multiple clinical trials that L-テアニン may support 入眠困難 management. Our evidence grade is A (Strong Evidence).

How much L-テアニン should I take for 入眠困難?

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 入眠困難?

We rate the evidence as Grade A (Strong Evidence). This rating is based on 4 peer-reviewed studies with 590 total participants. The overall direction of effect is positive.

に関する他の成分：入眠困難

ビタミンB6 A グリシン酸マグネシウム A 亜鉛 A メラトニン A Hops A アピゲニン B

L-テアニン他の症状・状態について

不眠症 A 不安に伴う睡眠障害 B

総合評価

合計590名の参加者を対象とした4件の研究（メタアナリシス2件、RCT 1件を含む）に基づく。4件中3件の研究で肯定的な効果が示されている。

Evidence Strength92%

High confidence

研究の内訳

RCT (0)Meta (0)Other (4)

代替成分との比較

この症状に対する他の成分との比較をご覧ください。

に関するすべての成分を見る：入眠困難

詳しく見る

References

[1] Jack Cotter et al.. Nutr Neurosci. 2026. Examining the effect of L-theanine on sleep: a systematic review of dietary supplementation trials. doi:10.1080/1028415X.2025.2556925 PubMed
[2] Su Eun Lim et al.. Front Nutr. 2024. Dietary supplementation with Lactium and L-theanine alleviates sleep disturbance in adults: a double-blind, randomized, placebo-controlled clinical study. doi:10.3389/fnut.2024.1419978 PubMed
[3] Suhyeon Kim et al.. Pharm Biol. 2019. GABA and l-theanine mixture decreases sleep latency and improves NREM sleep. doi:10.1080/13880209.2018.1557698 PubMed
[4] Jessica R Barrett et al.. J Child Adolesc Psychopharmacol. 2013. To sleep or not to sleep: a systematic review of the literature of pharmacological treatments of insomnia in children and … doi:10.1089/cap.2013.0059 PubMed

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。

L-テアニン ： 入眠困難