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Amino Acid

L-Tryptophan (Sleep)

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L-Tryptophan (Sleep). Direct serotonin/melatonin precursor for nocturnal use.

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

What the research supports. 1 graded claims. Strongest: Improves sleep onset and depression-related insomnia (moderate).

How much to take. Typical dose: 1–3 g before bed.

Side effects and interactions. 1 medication interaction listed. No serious side effects listed at normal doses.

Stacking. Pairs well with Magnesium glycinate, L-theanine.

Common forms. Available as Free-form crystalline powder, Capsules or tablets, Pre-mixed recovery or hydration beverages, Time-release formulations.

Key studies. 8 studies cited. The strongest are listed with links to PubMed.

Community. Experiences from people who have tried L-Tryptophan (Sleep). Anecdotes are not medical advice.

L-Tryptophan (Sleep). Direct serotonin/melatonin precursor for nocturnal use.

Molecular structureC11H12N2O2 · 204.22 g/mol

What it is

Direct serotonin/melatonin precursor for nocturnal use.

Food sources

Dietary protein from animal sources (meat, fish, eggs, dairy) and plant sources (soy, legumes, grains)Free-form amino acid powders and capsulesTargeted pre-workout, recovery, or sleep formulations

Goals

Sleep & RecoveryMood & Anxiety

How it works

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

Pathways

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

Effects

  • +sleep onset and depression-related insomnia supports

What the research supports

Improves sleep onset and depression-related insomniamoderate

Strong: consistent results across large trials or meta-analyses. Moderate: several trials, mostly positive. Limited: small or mixed studies. Preclinical: animal or cell research only.

Typical dose
1–3 g before bed
TimingConsistent daily timing recommended; split larger doses if GI tolerance is a concern.
With foodWith small carb snack
Best formMost evidence is based on the free-form crystalline powder form.
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Side effects & interactions

Common side effects

  • Drowsiness

Medication interactions

SSRIs/MAOIssevere

Serotonin syndrome risk.

Check any supplement–medication combination with your pharmacist before starting.

Combines with

Pairs well

Common forms

  • Free-form crystalline powder
  • Capsules or tablets
  • Pre-mixed recovery or hydration beverages
  • Time-release formulations

Key studies

8 studies cited in total.

PubMed: L-Tryptophan (Sleep) — Improves sleep onset and depression-related insomnia ↗
Systematic review · PubMed (NLM) · 2026

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.

PubMed: L-Tryptophan (Sleep) — randomized controlled trial ↗
Systematic review · PubMed (NLM) · 2026

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.

PubMed: L-Tryptophan (Sleep) — meta-analysis ↗
Systematic review · PubMed (NLM) · 2026

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

Discussion

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