5-HTP is a natural plant extract from the seeds of the West African griffonia simplicifolia tree. This plant extract is a natural source of 5-hydroxy-tryptophan (5-HTP). 5-HTP is a substance that is made in the body which is converted into serotonin, a brain chemical messenger. Low serotonin levels are believed to be the reason for many cases of mild to moderate depression, insomnia and feelings of anxiety, apathy, fear and worthlessness.