5-hydroxytryptophan (5-HTP) is a precursor to serotonin. In the body, the essential amino acid tryptophan (when acted upon by the enzyme tryptophan hydroxylase) converts to 5-HTP. The compound is subsequently decarboxylated to serotonin, thereby elevating extracellular serum serotonin levels.

Serotonin regulates many normal brain activities, increases norepinephrine and dopamine, and is important in regulating mood and behavior. Adequate levels of serotonin are associated with normal calmness and relaxation.Several studies have demonstrated that 5-HTP supports a healthy frame of mind, good energy levels, ease of movement, and restful sleep.