Melatonin is a hormone that contributes to the smooth functioning of our sleep-wake cycle. It is produced by the pineal gland, a very small structure in the center of the brain, and secreted into the blood. Production of melatonin is “switched off” by light coming into the eye, and “switched on” after dark. It causes drowsiness and lowering of body temperature, natural signals that it’s time for sleep.
There may be a connection between inadequate melatonin levels and increased risk of developing advanced prostate cancer. Production of this hormone tends to diminish naturally as people age, but other factors can also affect sufficient melatonin. According to doctoral candidate Sarah C. Mark (Dept. of Epidemiology, Harvard School of Public Health, Boston MA), “Sleep loss and other factors can influence the amount of melatonin secretion or block it altogether, and health problems associated with low melatonin, disrupted sleep, and/or disruption of the circadian rhythm are broad, including a potential risk factor for cancer…We found that men who had higher levels of melatonin had a 75 percent reduced risk for developing advanced prostate cancer compared with men who had lower levels of melatonin.”[i]
This conclusion was reached as an adjunct of a study of 928 Icelandic men from 2002 to 2009. 111 of them were diagnosed with prostate cancer, of whom 24 had advanced disease. When correlated with their morning melatonin levels as well as questionnaires regarding sleep habits, a connection was established between low levels and prostate cancer risk/progression.
While more study is needed, it is worth noting that habitual sleep disturbance contributes to a variety of physical and emotional difficulties. Add the possibility of increased prostate cancer risk, and it becomes one more reason to embrace practices that reinforce a good night’s sleep.