L-Tryptophan
Commonly used for
SleepMood
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The cheapest product is usually low quality, but more expensive doesn’t always mean better.
What is it? / Overview
Tryptophan is the precursor to serotonin and, downstream, melatonin; supplementation raises serotonin availability, which reduces sleep latency and wake-after-sleep-onset, particularly at doses of 1 g or more, per meta-analysis.
How is it used? / Administration
Form: L-tryptophan amino acid -- distinct from 5-HTP, a related downstream compound already covered separately
Typical dose studied: 1 g/day or more for sleep benefit
Timing: Before bed for sleep; some data support morning intake for mood/circadian effects
Critical historical flag: the 1989 eosinophilia-myalgia syndrome outbreak (which prompted a temporary FDA ban) was traced to a contaminated manufacturing batch, not tryptophan itself -- emphasize pharmaceutical-grade sourcing. Keep distinct from 5-HTP. Serotonin syndrome risk with serotonergic medications is the key interaction to flag.
How well does it work? / Evidence
~ Moderate evidence
Who should avoid it?
Avoid with: End-stage liver disease / Cirrhosis; Breastfeeding
Interacts with: SSRIs, SNRIs, MAOIs, triptans, tramadol, other serotonergic agents -- additive serotonin, risk of serotonin syndrome; CNS depressants -- additive sedation
Already taking it? Reasonable to continue if sourced from a reputable pharmaceutical-grade manufacturer -- a 1989 eosinophilia-myalgia syndrome outbreak was traced to a single contaminated manufacturing batch, not the amino acid itself, but sourcing quality matters.
Research & references
Sutanto CN et al. (2022). The Impact of Tryptophan Supplementation on Sleep Quality: A Systematic Review, Meta-Analysis, and Meta-Regression. Nutrition Reviews. Zhao M et al. (2020). The Effects of Dietary Nutrition on Sleep and Sleep Disorders. Mediators of Inflammation.
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