5-HTP supplements are popular among people who want to promote mental performance, relaxed mood, and healthy sleep. 5-HTP is a naturally occurring amino acid and a building block of a neurotransmitter called serotonin. Serotonin is important because it is believed to regulate anxiety, mood and appetite. Low serotonin levels in the brain are associated with depression, high anxiety, and insomnia. 5-HTP cannot be obtained directly from food sources, which is why supplements containing 5-HTP are popular. Mason Natural 5-HTP contains a high-potency 200 mg of 5-HTP per tablet from griffonia simplicifolia seed extract.