Melatonin is a hormone produced by the pineal gland present in the brain in response to darkness. It is mainly synthesized by the pinealocytes from the amino acid tryptophan which is hydroxylated and then decarboxylated in serotonin. It helps in maintaining circadian rhythms (the body 24 hour internal clock) and beyond sleep, it influences the biological process in the body including the immune system, neuroendocrine and cardiovascular functions. The secretion of melatonin is enhanced by darkness and inhibited by light. 

The metabolism of melatonin is quick and mainly occurs in the liver and secondarily in the kidney. The metabolic activity involves the hydroxylation of melatonin to 6-hydroxy melatonin with the help of cytochrome P450 which further conjugates with sulfuric acid (10%) or glucuronic acid (10%) and is finally excreted in the urine. Melatonin possesses excellent anti-inflammatory, antioxidant and mitochondrial protective properties. Melatonin is highly useful for issues of insomnia and refreshes the body and mind by providing sound sleep.