Originally published 2/10/2014
Looking at the 2014 date of the blog posted over seven years ago, you might wonder if the information is “old hat” by now. Thus, it’s worth updating with much more recent insight. Two new studies support the original blog’s message that low melatonin levels raise the chance of developing prostate cancer (PCa).
A study published almost exactly seven years later offers an explanation of the complex internal system between hormones and cancer risk. Melatonin is a hormone produced by the brain. Its levels are dependent on normal patterns of light during the day and darkness at night. Hadadi & Acloque write that the internal day-and-night clock of circadian rhythm regulates “…numerous endocrine functions, and its imbalances can have serious consequences… This is particularly true for the development of endocrine-related cancers, like breast, ovarian and prostate cancer. Circadian rhythm disorder (CRD) not only affects key hormone levels (including oestrogen, melatonin, insulin, glucagon, cortisol) but also favours a pro-inflammatory and immunosuppressive phenotype in the tumour microenvironment.”[i] The last point is particularly important. I have posted numerous blogs on how inflammation fosters PCa.
A March, 2021 study by Shen, et al. reviews several epidemiological studies linking disrupted circadian rhythm (e.g., shift work or light pollution) with increased PCa risk[ii]. When these patterns are disturbed, “… disrupted secretion and low blood levels of melatonin may elevate the risk of PCa in humans.” The upside of the Shen paper is a suggestion that for PCa patients on androgen deprivation therapy (ADT or chemical castration), melatonin supplements may have therapeutic benefit in terms of a positive interaction with the androgen receptor pathway. In turn, boosting effectiveness may add to survival.
The moral of the story is, honor your circadian rhythm and get a good night’s sleep.
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.”[iii]
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.
NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.
[i] Hadadi E, Acloque H. Role of circadian rhythm disorders on EMT and tumour-immune interactions in endocrine-related cancers. Endocr Relat Cancer. 2021 Feb;28(2):R67-R80.
[ii] Shen D, Ju L, Zhou F, Yu M et al.The inhibitory effect of melatonin on human prostate cancer. Cell Commun Signal. 2021; 19: 34.