SYS ONLINE
SUPPLEMENT_SCHOLAR
evidence · mechanism · dose
Supplements/Amino Acid

L-Tryptophan (Sleep)

Direct serotonin/melatonin precursor for nocturnal use.

Sleep & RecoveryMood & Anxiety

Overview

Direct serotonin/melatonin precursor for nocturnal use.

Natural sources
    Common forms

      Forms & variants of L-Tryptophan

      Different chemical forms of L-Tryptophan behave differently. Browse each form's mechanism, bioavailability, and best-use context.

      Parent
      L-Tryptophan

      Essential amino acid precursor to serotonin and melatonin.

      Mechanism of action

      Competes with LNAA at BBB; carb intake increases brain uptake via insulin.

      Pathways

        Effects on the body

        Organ system effects

        Evidence-based benefits

        Improves sleep onset and depression-related insomnia

        Moderate evidence

        Potential side effects

        Common
        • · Drowsiness
        Rare
        • · Eosinophilia-myalgia syndrome (historic contaminant)
        Serious

          Drug interactions

          SSRIs/MAOIs
          Serotonin syndrome risk.
          severe

          Safety & non-supplemental interactions

          Educational summary — always confirm with your clinician or pharmacist before starting, stopping, or combining with prescription therapy.

          Avoid / monitor with these medications
          • ·Alcohol, benzodiazepines, opioids, sedating antihistamines (additive CNS depression)

          Supplement interactions

          Pairs well with

          None listed.

          Avoid combining with

          No specific avoidances listed.

          Dosing & bioavailability

          Typical dose
          1–3 g before bed
          With food?
          With small carb snack

          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.

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

          Scientific evidence (8)

          RCTJ Nerv Ment Dis · 1979

          Tryptophan in chronic insomnia

          Hartmann E, Spinweber CL

          Crossover DB-RCT in 15 insomniacs.

          Key findings

          1 g L-tryptophan reduced sleep latency vs placebo.

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: L-Tryptophan (Sleep) — Improves sleep onset and depression-related insomnia

          Live PubMed search

          Live results for "L-Tryptophan (Sleep) Improves sleep onset and depression-related insomnia" across the PubMed/MEDLINE peer-reviewed index.

          Key findings

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

          Open study
          Systematic reviewPubMed (NLM) · 1970

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

          Live PubMed search

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

          Key findings

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

          Open study
          Systematic reviewPubMed (NLM) · 1970

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

          Live PubMed search

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

          Key findings

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

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: L-Tryptophan (Sleep) — pharmacokinetics

          Live PubMed search

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

          Key findings

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

          Open study
          Systematic reviewPubMed (NLM) · 1970

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

          Live PubMed search

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

          Key findings

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

          Open study
          Systematic reviewPubMed (NLM) · 1970

          PubMed: L-Tryptophan (Sleep) — dose response

          Live PubMed search

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

          Key findings

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

          Open study
          Systematic reviewGoogle Scholar · 1970

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

          Live Scholar search

          Cross-database citation index for L-Tryptophan (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.