5-HTP is a precursor to serotonin and is synthesized in the body from the amino acid L-Tryptophan. Serotonin is known as the neurotransmitter responsible for happiness. Serotonin can also impact sleep, appetite, temperature, and pain sensation.

5-HTP has been found to effectively reduce the time to fall asleep and as well as improve sleep duration. 5-HTP has also been implicated in one study to be protective against stress and anxiety. Some studies also show that 5-HTP can improve satiety and reduce appetite, helping to improve weight loss results.