What it is
An essential aromatic amino acid required for protein synthesis and serving as the precursor to serotonin, melatonin, and niacin. Available as oral capsules and tablets.
How it works
Crosses the blood-brain barrier via the large neutral amino acid transporter and is hydroxylated to 5-HTP, then decarboxylated to serotonin. Also feeds into the kynurenine pathway peripherally.
Where it's used
Used as a dietary supplement marketed for sleep and mood.
FDA-approved use
Regulated as a dietary supplement.
Tracking it
L-Tryptophan is oral, which makes consistency the whole game — a simple daily check-off with a reminder beats memory every time. with a half-life of about 2 hours, a dose log also lets a tracker model the relative amount still in your system between doses.
Source
Public reference
Not medical advice. This page is an educational summary compiled from public
sources for people who log what they take. It is not a recommendation to use
L-Tryptophan, a dosing guide, or a substitute for a clinician.
How we source →
Last reviewed 2026-06-11