L-Tryptophan is a natural amino acid contained in food. In our body L-Tryptophan is part of the “sleep biochemical pathway” as follows: L-Tryptophan is metabolized to Serotonin, and then Serotonin is metabolized to Melatonin. Once the Melatonin concentration is built up in the brain, we feel the need to sleep. Please read the relevant section of the three US Patents for ClearSleep®. Serotonin and Melatonin are regulated as drugs in many countries around the world (not in the US). Providing L-Tryptophan to the body is a 100% natural way to gently trigger the “sleep biochemical pathway”.