5-HTP, the intermediate metabolite between the amino acid L-tryptophan and serotonin, is extracted from the seed of an African plant (Griffonia simplicifolia). 5-HTP readily crosses the blood-brain barrier and increases central nervous system (CNS) synthesis of serotonin. Serotonin can affect sleep, and many other important biological functions. This is a mid-range dosage of 5-HTP.