"Light at night is now clearly a risk factor for breast cancer . . . Breast tumors are awake during the day, and melatonin puts them to sleep at night." Add artificial light to the night environment, and "cancer cells become insomniacs." . . .compared with other workingwomen, female night-shift workers have about a 50 percent greater risk of developing breast cancer . . . Blind women, by contrast, have unusually low rates of breast cancer and high average melatonin concentrations . . ."Almost nobody who does shift work adapts to it," . . . On their days off, most shift workers concentrate their activities during daylight[.]
This news suggests that light exposure control and other mealtonin level oriented therapies may play an increasing role in cancer treatment and prevention. There is some indicatation that cancers other than breast cancer may also be impacted, including prostate cancer in men. It takes bright light to impact melatonin production, so simply dimming lights may help. And, melatonin supplements are available as a cheap vitamin over the counter. These supplements may become the cancer treatmen equivalent of aspirin and daily glasses of alcohol in treating heart disease.