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evidence · mechanism · dose
Supplements/Amino Acid

L-Theanine (Sleep)

Tea-derived amino acid that raises alpha brainwaves — relaxation without sedation.

Sleep QualityAnxiety SupportStress RecoveryFocus

Overview

Tea-derived amino acid that raises alpha brainwaves — relaxation without sedation.

Natural sources
    Common forms

      Mechanism of action

      Crosses BBB; raises GABA, glycine, and serotonin; promotes alpha brain wave activity.

      Pathways

        Effects on the body

        Organ system effects

        Evidence-based benefits

        Improves sleep quality (not onset)

        Moderate evidence

        Reduces stress markers

        Moderate evidence

        Potential side effects

        Common
          Rare
            Serious

              Drug interactions

              No notable interactions reported.

              Supplement interactions

              Pairs well with

              None listed.

              Avoid combining with

              No specific avoidances listed.

              Dosing & bioavailability

              Typical dose
              200–400 mg
              With food?
              Optional

              Where to buy

              Affiliate-style search links to reputable retailers. We don't endorse specific brands — verify third-party testing (USP, NSF, Informed Sport) before purchase.

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              Amazon
              Wide selection · fast shipping
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              iHerb
              Global delivery · curated brands
              Amino Acid
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              Thorne
              Practitioner-grade · NSF tested

              Scientific evidence (9)

              RCTNutrients · 2019

              L-theanine on stress and sleep quality

              Hidese S, et al.

              4-week RCT of L-theanine 200 mg/d.

              Key findings

              Improved sleep quality and reduced stress scores.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Theanine (Sleep) — Improves sleep quality

              Live PubMed search

              Live results for "L-Theanine (Sleep) Improves sleep quality" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Theanine (Sleep) and "Improves sleep quality". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Theanine (Sleep) — Reduces stress markers

              Live PubMed search

              Live results for "L-Theanine (Sleep) Reduces stress markers" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Theanine (Sleep) and "Reduces stress markers". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Theanine (Sleep) — randomized controlled trial

              Live PubMed search

              Live results for "L-Theanine (Sleep) randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Theanine (Sleep) and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Theanine (Sleep) — meta-analysis

              Live PubMed search

              Live results for "L-Theanine (Sleep) meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Theanine (Sleep) and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Theanine (Sleep) — pharmacokinetics

              Live PubMed search

              Live results for "L-Theanine (Sleep) pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Theanine (Sleep) and "pharmacokinetics". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Theanine (Sleep) — safety adverse events

              Live PubMed search

              Live results for "L-Theanine (Sleep) safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Theanine (Sleep) and "safety adverse events". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewPubMed (NLM) · 1970

              PubMed: L-Theanine (Sleep) — dose response

              Live PubMed search

              Live results for "L-Theanine (Sleep) dose response" across the PubMed/MEDLINE peer-reviewed index.

              Key findings

              Opens current human and preclinical literature matching L-Theanine (Sleep) and "dose response". Filter by RCT, meta-analysis, or year on the results page.

              Open study
              Systematic reviewGoogle Scholar · 1970

              Google Scholar: L-Theanine (Sleep) — clinical evidence

              Live Scholar search

              Cross-database citation index for L-Theanine (Sleep) as it relates to "clinical evidence".

              Key findings

              Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

              Open study
              Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.