Prostate : Melatonin May Reduce Prostate Cancer Risk

Men with higher levels of the sleep hormone melatonin may be less likely to develop prostate cancer, a new study suggests.

The research also revealed that men who had higher levels of melatonin in their urine had a 75 percent decreased risk of advanced prostate cancer, compared with men with lower melatonin levels, Cancer Research UK wrote.

"It's notable that we found a stronger association between melatonin levels and more advanced prostate cancer," said study researcher Sarah Markt, a doctoral candidate in the department of epidemiology at the Harvard School of Public Health in Boston.

People's melatonin levels are affected by the amount of sleep they get, and the quality of that sleep. The hormone is produced in the brain by the pineal gland in response to darkness. Melatonin levels typically rise in the evening, promoting sleep, and peak during the night. Levels then fall in the morning, as sunlight and indoor light use increases, encouraging wakefulness.

But people who have irregular sleep schedules from shift work hours, as well as people who wake up a lot during the night and turn on the lights, disrupt their circadian rhythm-the body's internal clock-and produce less melatonin, the researchers said.

Earlier research has suggested that melatonin plays a role in regulating hormones that influence cancer. Test-tube studies have shown that melatonin may help slow or stop the growth of cancer cells.

And there's some evidence that women who work night shifts for many years have lower levels of melatonin and a slightly higher risk of breast cancer, according to the American Cancer Society.

The recent study found that men who had melatonin levels above the midpoint of 17.1 nanograms per milliliter had a 30 percent lower overall risk of prostate cancer, and a 75 percent lower risk of developing an advanced form of the disease, compared with men whose melatonin levels were below the midpoint.

Men with sleep problems--those who took sleep medications, or had trouble falling asleep or staying asleep--had lower levels of melatonin than men with no difficulty sleeping

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