Serotonin, an important brain neurotransmitter, is key in the regulation of appetite, mood, and melatonin production. The presence of serotonin in the brain is associated with a balanced emotional state. This is achieved in part by decreasing the activity of certain excitatory hormones, including dopamine and noradrenaline. Serotonin also acts as a satiety signal in the brain, thereby naturally regulating food intake. Additionally, as a precursor of melatonin, serotonin is involved in regulating sleep patterns. Serotonin is unable to cross the blood-brain barrier and is therefore synthesized in the brain. Tryptophan, an essential amino acid, is a precursor for the synthesis of serotonin. Tryptophan crosses the blood-brain barrier and is converted to L-5-Hydroxytryptophan (5-HTP), which in turn is converted into serotonin. Vitamins B2 and B6, niacinamide and Vitamin C are necessary cofactors to ensure the proper synthesis of serotonin. Studies indicate that supplementation with L-tryptophan may support healthy mood and restful sleep.€ Other studies indicate L-tryptophan may support women’s emotional well being before menstruation. Additional research indicates L-tryptophan may be helpful in supporting healthy relaxation and occasional food cravings.