Melatonin (N-acetyl-5-methoxy-tryptamine) is a hormone synthesized from the amino acid tryptophan in the brain’s pineal gland.Research has shown that Melatonin in humans has its highest levels in plasma during nighttime and appears to encode temporal information such as length of night. Noradrenaline/norepinephrine maybe linked to the release of Melatonin. The liver metabolizes melatonin by converting the hormone into 6-hydroxymelatonin and subsequently to 6-sulfatoxymelatonin which is excreted into the urine. Research suggests the concentration of 6-hydroxymelatonin sulfate in urine correlates well with the total level of melatonin in the blood during the collection period.