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Sleep/Diseases
Breast / Prostate Cancer preventionWe probably all know someone who has either breast or prostate cancer, as they are the most commonly diagnosed cancers in females and males respectively. Although family history is an uncontrollable risk factor in both cancers, there are many other risk factors that we can control, and may determine whether or not cancer develops.
There is more and more evidence linking artificial evening and night-time light to the growth of cancer cells. The risk of breast cancer is five times higher in industrial nations lit with electric lights than in the underdeveloped countries of the world. A study done in 2001 by the Fred Hutchison Cancer Research Centre in Seattle found that women who worked the graveyard shift had a 60% greater risk of getting breast cancer than those that did not. Women that regularly sleep nine hours a night have less than a third the cancer rates of those that regularly sleep seven, according to a Finnish study published in Cancer Research in 2005. Interestingly, it does not seem to be the sleep that matters, but rather the hours spent in darkness.
Melatonin is the immune hormone that is secreted in darkness. Melatonin is supposed to be at its peak between 1 and 2am, and if we are still up with the lights on at that time, very little or no melatonin will be secreted. Melatonin seems to stop cancer cells cold, and puts them to sleep for the night. Breast cancer grows in the presence of light, because of the absence of melatonin. In a very interesting study published in Dec. of 2005 and funded by the NIH, rats that were implanted with human breast cancer were either given melatonin rich blood from women that had been in complete darkness for 2 hours, or blood from women that were exposed to bright light. The tumors in the rats that were given blood with the lowest melatonin concentrations (the blood that came from women exposed to light) multiplied the fastest. Melatonin seems to block the ability of cancer cells to metabolize linoleic acid, the omega 6 fatty acid that is found in vegetable oils, thereby preventing the cancer cells from dividing. Melatonin also seems to have a role in controlling the excess production of estrogen and estradiol, another factor in the growth of breast cancer.
Although there is less research with regard to the protective effects of melatonin on prostate cancer, the research that is there certainly does support the hypothesis, and more research is ongoing. Melatonin seems to be protective in some other cancers as well, such as skin cancer, The message for us all? Get to bed early enough that you will get 9 hours of dark time, and use a red night light if you need to use the bathroom in the night. If going to bed early on a regular basis is impossible for you, get black-out drapes and make sure you get you can sleep in long enough in the morning to get your nine hours of dark time. Reducing your consumption of omega 6 fatty acids - vegetable oils like soy, canola, sunflower etc, grain-fed beef etc., and increase omega 3 intake from fish oils in order to improve the omega 6 to omega 3 ratio may also assist in reducing your risk of getting cancer.
Related tips:
Light Pollution Messes With Your Hormones
Vegetable Oils - Friend or Foe?
Essential Fats - Omega 3 to Omega 6 Ratio
Davis, Scot et al. Light at Night and Working the Graveyard Shift Linked to Increased Risk of Breast Cancer Journal of the National Cancer Institute October 2001
Blask, David, MD, PhD et al. Melatonin-Depleted Blood from Pre-Menopausal Women Exposed to Light at Night Stimulates Human Breast Cancer Xenografts in Nude Rats Cancer Research 65, 11174-11184, Dec. 1, 2005.
Verkasalo, P. et al. Sleep Duration and Breast Cancer: A Prospective Cohort Study Cancer Research 65, 9595-9600, Oct. 15, 2005.
Harder, Ben. Bright Lights, Big Cancer Science News Online Jan. 7, 2006.
Sainz. RM et al. Melatonin reduces prostate cancer cell growth leading to neuroendocrine differentiation via a receptor and PKA independent mechanism Prostate 63(1) 29-43, April 1, 2005.
Moretti RM et al. Antiproliferative action of Melatonin on human prostate cancer LNCaP cells Oncol Rep 2000 7(2):347-351.
Fraschini F. et al. Melatonin involvement in immunity and cancer Biol Signals Recept 1998, 7(1): 61-72.
Copyright 2006 Vreni Gurd