Other roles for this natural hormone are considerably more controversial.
Some advocates claim it can hold back the spread of cancer.
Others say it can delay the onset of aging, improve the symptoms of Alzheimer's disease, lower cholesterol levels, and reduce high blood pressure. However, most doctors feel that its effectiveness for these purposes remains to be proven. Under normal conditions, Melatonin levels foreshadow the sleep cycle, usually increasing rapidly from the late evening until midnight, then decreasing as morning approaches. Not surprisingly, people with high levels of Melatonin usually sleep longer and more soundly than those with a deficiency. For example, the elderly, who produce less Melatonin than the young and middle-aged, are typically more susceptible to insomnia.