Answer:
darkness; light
Explanation:
Made by the body, melatonin not only regulates bedtime but also helps repair our cells exposed to stress, pollution and other harmful elements. It is a powerful antioxidant and fights free radicals that attack the body. In sync with the end of the day and the light, it is now released to prepare the body for the night. This is because the release of melatonin is stimulated by darkness and inhibited by light.
