Overview
Direct serotonin/melatonin precursor for nocturnal use.
- Dietary protein from animal sources (meat, fish, eggs, dairy) and plant sources (soy, legumes, grains)
- Free-form amino acid powders and capsules
- Targeted pre-workout, recovery, or sleep formulations
- Free-form crystalline powder
- Capsules or tablets
- Pre-mixed recovery or hydration beverages
- Time-release formulations
Forms & variants of L-Tryptophan
Different chemical forms of L-Tryptophan behave differently. Browse each form's mechanism, bioavailability, and best-use context.
Mechanism of action
Competes with LNAA at BBB; carb intake increases brain uptake via insulin.
- · Competes with LNAA at BBB
- · carb intake increases brain uptake via insulin
Effects on the body
Organ system effects
L-Tryptophan (Sleep) promotes parasympathetic tone, GABAergic signaling, or melatonergic pathways that facilitate sleep onset and quality.
Evidence-based benefits
Improves sleep onset and depression-related insomnia
Moderate evidencePotential side effects
- · Drowsiness
- · Eosinophilia-myalgia syndrome (historic contaminant)
Drug interactions
Safety & non-supplemental interactions
Educational summary — always confirm with your clinician or pharmacist before starting, stopping, or combining with prescription therapy.
- ·Alcohol, benzodiazepines, opioids, sedating antihistamines (additive CNS depression)
Supplement interactions
- Magnesium glycinateComplementary GABAergic calming and improved sleep architecture.
- L-theanineReduces sleep latency without sedation.
No specific avoidances listed.
Dosing & bioavailability
Where to buy
Affiliate links — we may earn a commission at no extra cost to you. Amazon code supplementsch-20 is auto-applied at checkout. We don't endorse specific brands; verify third-party testing (USP, NSF, Informed Sport) before purchase.
Third-party testedIndependently verified L-Tryptophan (Sleep) — look for USP, NSF, or Informed Sport seals on the label for purity and dose accuracy.L-Tryptophan (Sleep) third party tested NSF
CapsulesPre-measured L-Tryptophan (Sleep) capsules — easiest for travel and consistent daily dosing without scoops or scales.L-Tryptophan (Sleep) capsules
PowderBulk unflavored L-Tryptophan (Sleep) powder — best cost-per-gram and flexible dosing for stacking or mixing into drinks.L-Tryptophan (Sleep) powder unflavored
Best sellersMost-purchased L-Tryptophan (Sleep) products on Amazon — a quick way to see what's reviewed widely before you commit.L-Tryptophan (Sleep) best sellerScientific evidence8Show studiesHide studies
Tryptophan in chronic insomnia
Hartmann E, Spinweber CL
Crossover DB-RCT in 15 insomniacs.
1 g L-tryptophan reduced sleep latency vs placebo.
PubMed: L-Tryptophan (Sleep) — Improves sleep onset and depression-related insomnia
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PubMed: L-Tryptophan (Sleep) — randomized controlled trial
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PubMed: L-Tryptophan (Sleep) — meta-analysis
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PubMed: L-Tryptophan (Sleep) — pharmacokinetics
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PubMed: L-Tryptophan (Sleep) — safety adverse events
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PubMed: L-Tryptophan (Sleep) — dose response
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Google Scholar: L-Tryptophan (Sleep) — clinical evidence
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Cross-database citation index for L-Tryptophan (Sleep) as it relates to "clinical evidence".
Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.