It is manufactured in that gland from serotonin. It is believed that manufacturing and secreting melatonin is the sole function of the pineal gland. As a powerful antioxidant Several Double blind studies have shown that melatonin supplementation is effective in promoting sleep when melatonin levels are low. If one takes melatonin when levels are not reduced, then it has no effect. The reason for this is that the body normally secretes melatonin just before bedtime.
Darkness stimulates melatonin secretion while light suppresses it.
Low melatonin levels are a very common cause of insomnia and restlessness. In jet-lag, the natural body clock may not allow for secretion of melatonin at the appropriate time, thereby making melatonin supplementation useful. Melatonin possesses antioxidant qualities. Kirkman's Melatonin Plus also contains magnesium . Magnesium deficiency can cause insomnia as well as hyperactivity responses such as irritability and sound sensitivity.