This book, on the pineal hormone melatonin, is addressed to a wide non-cognizant and cognizant readership. The hormone appears to be involved in sleep onset and other functions associated with the body s clock, the suprachiasmic nucleus. It is ubiquitous throughout both the animal and plant kingdoms and has a long evolutionary history as a hormone. Melatonin has a major role in the regulation of circadian rhythms in non-mammalian vertebrates and forms part of their control in mammals. The present text emphasizes the positive role of exogenously administered melatonin, and its synthetic derivatives, on disrupted circadian rhythm-related dysfunctions. This is effected by resetting the clock in jet lag sufferers and those with seasonal affective disorders, insomnia, and various neurological conditions.
