We 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.

In the last couple of posts I discussed how degenerative diseases were not common before 1900, and how the radical change in our diet since that time is probably a primary factor contributing to the explosion in those degenerative diseases that has occurred in the last century. Another very significant change that has occurred over the last 75 years, is our ability to control the amount of light that we are exposed to thanks to the invention of the light bulb. Currently our lives are awash with artificial light late into the night long after the sun has gone down, and we don't give it a second thought unless we are in the middle of a power failure which forces us, much to our dismay, into darkness. Could all this light be contributing to disease as well? Could it be we need the yin as well as the yang?

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 only in complete 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. So by getting adequate dark time and by reducing the amount of linoleic acid available to potential cancer cells to feed on by reducing our consumption of vegetable oils like soy, canola, sunflower etc. we may have a strategy to reduce the risk of getting cancer.

The recent statistics that have come out have indicated a big drop in rates of breast cancer, and it is believed that this drop was due to the reduced use of hormone replacement therapy in 2002, solidifying the theory that high estrogen levels play a roll in developing breast and also cervical cancer. Estrogen dominance may also occur as a result of chronically high insulin levels, so decrease your sugar and starchy carbohydrates if there is breast cancer in your family, and get your dark time, as melatonin also seems to have a role in controlling the excess production of estrogen and estradiol. It is interesting to note that decreased melatonin levels due to too little dark time results in increased levels of cortisol, which in turn translates into higher insulin levels, which leads to problems with type 2 diabetes and heart disease in addition to cancer. So, the bottom line is that getting enough hours in complete darkness is vital to hormone regulation, which is vital to optimal health.

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, colorectal cancer and even lung cancer. The message for us all? First, 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. Second, reduce your consumption of omega 6 vegetable oils, and third, reduce your consumption of sugar and high glycemic (starchy) foods.

Related tips:
Light Pollution Messes With Your Hormones
Is going to bed too late making you fat?
Fats, the good, the bad and the ugly (it's not what you think!)
Sugar, the disease generator

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