L-Tryptophan is an essential amino acid, which means that our body can not produce for itself and should be taken exogenously to the organism. Tryptophan acts as precursor of serotonin, a neurotransmitter implicated in the regulation of mood , stress, and rest. participates in the formation of melatonin. magnesium helps reduce tiredness and fatigue. amino acids are essential for many processes of our metabolism