<Li> Key: DRLFMBDRBRZALE - UHFFFAOYSA - N </Li> <Tr> <Th_colspan="2"> (verify) </Th> </Tr> <P> Melatonin, also known as N - acetyl - 5 - methoxy tryptamine, is a hormone that is produced by the pineal gland in animals and regulates sleep and wakefulness . Melatonin is also produced in plants where it functions as a first line of defense against oxidative stress . </P> <P> In animals, melatonin is involved in the entrainment (synchronization) of the circadian rhythms including sleep - wake timing, blood pressure regulation, seasonal reproduction, and many others . Many of its biological effects in animals are produced through activation of melatonin receptors, while others are due to its role as an antioxidant, with a particular role in the protection of nuclear and mitochondrial DNA . </P>

The part of the brain that regulates the production of the hormone melatonin is called