L-Tryptophan
Sole dietary precursor to serotonin and melatonin — supports mood regulation and natural sleep onset more gradually than 5-HTP.
L-Tryptophan is an essential amino acid that the body cannot produce, requiring dietary intake. It's the sole precursor to serotonin (the 'feel-good' neurotransmitter) and subsequently melatonin (the sleep hormone). Unlike 5-HTP, tryptophan is one step earlier in the synthesis pathway, offering a more gradual approach to supporting mood and sleep.
Converts to serotonin, supporting mood and well-being
Serotonin is further converted to melatonin for sleep
Can also be converted to niacin (vitamin B3)
How Tryptophan works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
500-1000mg before bed
Loading: Not applicable; start with lower dose and adjust
Can be taken without food
| Form | Type |
|---|---|
| 💊L-Tryptophan capsules | Recommended |
| 🧪Powder | Alternative |
| 💊Tablets | Alternative |
Use pharmaceutical-grade L-Tryptophan from reputable sources to ensure purity.
Minimum: 2 weeks
Optimal: 8 weeks
Cycling: Not required
Note: Taking with carbohydrates may enhance brain uptake by reducing competition from other amino acids. Avoid taking with high-protein foods.
Fall asleep more quickly
Better overall sense of well-being
Calming effect through serotonin pathway
May cause sleepiness if taken during the day
Consult healthcare provider; limited data
Start with lower doses; may be more sensitive to sedation
Risk of serotonin syndrome - do not combine
May enhance sedative effects
Increased serotonin syndrome risk
High risk of serotonin syndrome
Tip: Take only before bed; reduce dose if excessive
Tip: Take with a small amount of food
Top studies from 39+ peer-reviewed papers
Almulla AF et al. • Cells (2022)
“Patients with affective disorders with melancholic and psychotic features and suicidal behaviors showed normal IDO enzyme activity but a lowered availability of plasma/serum TRP to the brain, which is probably due to other processes such as low albumin levels.”
Hughes JR et al. • The Cochrane database of systematic reviews (2014)
“The antidepressants bupropion and nortriptyline aid long-term smoking cessation.”
Saarto T et al. • The Cochrane database of systematic reviews (2005)
“Antidepressants are effective for a variety of neuropathic pains.”
Ma T et al. • Cell reports. Medicine (2025)
“A randomized, double-blind, placebo-controlled crossover trial involving 110 adults with chronic constipation (Rome IV criteria) demonstrates that a 3-week Probio-Eco intervention significantly imp...”
Cheng YC et al. • Psychological medicine (2025)
“This extensive systematic review and NMA of nutraceuticals for treating depressive disorders indicated a number of nutraceuticals that could offer benefits, either as adjuncts or monotherapies.”
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