OstroVit - Histidine is an amino acid...
Scitec Nutrition's Tryptophan is an effective amino acid complex.
Dietary supplement OstroVit - Tryptophan is a precursor of serotonin, it is also an intermediate for the production of melatonin.
The amino acid L-tryptophan helps to maintain a relaxed state of the body, normalize sleep, give a positive mood and improve immune function.