Melatonin is a natural hormone nutrient that is synthesized from the amino acid tryptophan by the pineal gland in the back of the brain.
Most of the research on melatonin has focused on its role in maintaining normal sleep/wake rhythms. The rise in plasma melatonin levels is thought to be responsible for bringing on sleep. Nocturnal melatonin production is highest in children and begins to decline from adolescence on until it is virtually absent in the elderly.
Melatonin supports normal immune function by helping maintain the activity of circulating natural killer cells and it has also been found to function as an antagonist for stress induced immune suppression.
Melatonin is also considered a potent anti-oxidant that enters all body cells to help prevent free radical damage
Melatonin is perhaps the most important physiological anti-oxidant in the brain due to its lipid and water soluble properties as it can freely cross the blood brain barrier.
In vitro that melatonin is more effective than glutathione in scavenging toxic hydroxyl radicals and also more efficient than vitamin E in neutralizing peroxyl radical which can induce DNA damage
Melatonin also stimulates the main anti-oxidant enzyme of the brain, glutathione peroxidase.