L-tryptophan is an essential amino acid the body turns into serotonin and melatonin. It is sold for sleep and mood.
Calculator Official intake Study doses Best form Safety Sources
This is not an essential nutrient, so there is no official daily intake. Only study doses are shown.
These are doses tested in research, not personal advice. Some exceed the upper limit because they were short courses or given under medical care.
1 g a day
A meta-analysis found tryptophan shortened time awake after falling asleep, more with 1 g or more a day than with less. Other sleep measures did not change, and only 4 studies could be pooled.
No best form
Why: Studies used plain L-tryptophan. Because of the 1989 contamination disaster, choose products with independent quality testing.
Poultry, eggs, dairy, fish, soy, nuts and seeds.
Do not combine with antidepressants (SSRIs, MAO inhibitors), triptans or other drugs that raise serotonin: risk of serotonin syndrome.
In 1989 a contaminated batch from one maker caused eosinophilia-myalgia syndrome, with deaths; tryptophan was pulled from sale in the US for years. Buy from makers with good quality testing.
Pregnant, breastfeeding, on medication, or managing a health condition? Check with a doctor or pharmacist before starting a supplement.
Values checked: November 12, 2026.