Melatonin is a natural hormonal nutrient that is synthesized from the amino acid tryptophan by the pineal gland at the back of the brain, it is also present in small amounts in some foods.
In the body, Melatonin regulates sleep cycles, supports normal immune function and protects cells from free radical damage.
Most research on Melatonin is essentially based on its role in maintaining the normal rhythm of sleep.
The perception of daylight in the eyes is a signal for the pineal gland to inhibit the synthesis and release of melatonin, at night or in the dark, the production of melatonin in the body increases, being higher in children and beginning to decrease in adolescence, reaching minimum values ??in the elderly.
Melatonin supports normal immune function and functions as an antagonist in stress-induced immunosuppression. It is considered a potent antioxidant as it helps to prevent free radical damage.

In the brain, it is perhaps the most important physiological antioxidant, due to its water-soluble lipids, which are able to cross the blood-brain barrier freely.
In vitro studies show that melatonin is more effective than glutathione in eliminating toxic hydroxyl radicals and more efficient than vitamin E in neutralizing peroxyl radicals that can induce DNA damage.
The absorbed melatonin, which enters the bloodstream, is rapidly metabolized by the liver and is excreted by the kidneys.
The difference for oral melatonin, is that it is absorbed in the intestine, its absorption may be greater or lesser depending on the person, and ends in the liver, where much of the melatonin is destroyed. Hence the need for these supplements to present plants such as valerian, passionflower and others to try to mask the lack of effectiveness of melatonin.