L-tryptophan is one of the essential amino acids and cannot be produced (synthesized) by the body itself. The human organism is therefore dependent on a supply of the fat-soluble amino acid through food. In addition to its function as an important protein building block, L-tryptophan is required in the body to produce serotonin ("happiness hormone") and melatonin ("sleep hormone") - two important messenger substances that have a positive effect on mental well-being and the sleep rhythm.