L-Tryptophan is an essential amino acid; therefore, it is not synthesized by the body and must be obtained from the diet. In the brain, Tryptophan is converted into serotonin, a neurotransmitter involved in feelings of well-being, calmness, personal security, and relaxation. It also plays a role in the regulation of appetite and synchronization of sleep patterns. Every lot of Protocol For Life Balance L-Tryptophan is tested to be free of Peak E and microbial contamination.