CAUTION: Melatonin Supplementation . Obviously, getting adequate melatonin before bed is a good thing. Furthermore, supplemental melatonin is part of a multisupplement Sleep Aid cocktail that was recently found to be effective in patients suffering with insomnia. Nevertheless, some caution with supplemental melatonin may be in order, since it low dopamine levels.  Normal melatonin is important, though, and its antioxidant powers likely protect the cells of the substantia nigra.