L-Tryptophan
L-Tryptophan is an essential amino acid that serves as a direct precursor to serotonin, supporting mood and sleep improvement. It is often used for mood support, sleep enhancement, and managing symptoms of PMS and seasonal affective disorder.
Evidence last reviewed: 20 Apr 2026
The evidence for L-Tryptophan shows moderate effectiveness in improving sleep quality and mood. However, the studies vary in quality and sample size, indicating a need for further research.
sleep qualitygeneral population · Systematic reviewModerate
L-Tryptophan supplementation was found to aid in improving sleep quality.
mood improvementhealthy adults · Systematic reviewModerate
Tryptophan intake may decrease anxiety and increase positive mood in healthy individuals.
wake after sleep onsetindividuals with insomnia · Systematic reviewModerate
Tryptophan supplementation significantly shortened wake after sleep onset.
gut microbiota modulationhealthy subjects · RCTLow
Oral tryptophan activated duodenal aryl hydrocarbon receptor, influencing gut microbiota.
Sleep Quality and Relaxation
Combining Tryptophan with Passionflower can enhance sleep quality and promote relaxation. Tryptophan is a precursor to serotonin and melatonin, supporting sleep, while Passionflower is known for its calming effects.
Forms & usage▾
Take 500-1000 mg before bedtime for sleep support.