5-Hydroxytryptophan, an organic compound with the molecular formula C₁₁H₁₂N₂O₃, is an amino acid-like substance that acts as a precursor substance for 5-Hydroxytryptamine in the human body and is therefore thought to help increase 5-Hydroxytryptamine levels, but its role in sleep regulation and its therapeutic effect on depression remains controversial in academic circles.

5-Hydroxytryptophan (5-HTP), is an amino acid. It is used in the body as a precursor for 5-Hydroxytryptamine (serotonin, 5-HT) (and subsequently as a precursor for melatonin). Some double-blind studies have shown that 5-HTP can increase serotonin concentrations in the brain, improve depression and melatonin formation, improve sleep quality, and suppress appetite, but these studies are still problematic. Therefore, more researches are needed to confirm whether 5-HTP has these physiological effects. Griffonia Seeds are rich in 5-Hydroxytryptophan, which is currently the main natural source of 5-HTP production.

5-HTP can be converted into serotonin in the body, but serotonin cannot enter the brain through the blood-brain barrier. Therefore, 5-HTP must first pass through the blood-brain barrier and then be converted into serotonin in the brain in order to truly play a role in stabilizing mood and promoting sleep quality. After oral administration of 5-HTP, only about one-third to one-half of it can actually be converted into serotonin in the brain, and most of it will be converted into serotonin before it enters the blood circulation of the brain, which has no positive physiological effect.