线性范围：1ng/L -40ng/L.Melatonin, also known as N-acetyl-5-methoxy tryptamine,is a hormone that is produced by the pineal gland in humans and animals and regulates sleep and wakefulness.Melatonin is also produced in plants where it functions as a first line of defense against oxidative stress. 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.