Amino acid
Tryptophan
Tryptophan is an essential amino acid found in protein foods, which the body uses to make serotonin, melatonin and niacin.
Also listed as L-Tryptophan
What it is studied for
The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.
All 8 rated effectsGrouped by health goal, with the publications behind each rating
Key studies
The most recent publications linked to Tryptophan's ratings.
The impact of tryptophan supplementation on sleep quality: a systematic review, meta-analysis, and meta-regression.2021The Impact of Tryptophan Supplementation on Sleep Quality: A Systematic Review, Meta-Analysis and Meta-Regression2021Evaluation of l-tryptophan for treatment of insomnia: A review2004
Why people take it
Essential Health20.9%
Fitness16.1%
Energy15.6%
Immune Support11.6%
Stress & Mood6.8%
Sleep5.9%
SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.
5-HTP