Melatonin (below) helps regulate our circadian rhythm (day/night cycles). As melatonin levels rise we become sleepy. Interestingly, the nightly release of melatonin is typically delayed as children become teenagers, leading to later sleeping and waking times. Melatonin is also a powerful antioxidant.

A structural molecular model of the hormone Melatonin. It is an antioxidant and a regulator of circadian rhythms.