Lift Up Your Hearts!

I've occasionally wondered what we might be doing to ourselves by prolonging daylight with the use of artificial lights. A study by the U. S. National Cancer Institute and National Institute of Environmental Health Sciences presents evidence that the use of artificial light during the hours of darkness is a signficant risk factor in the development and progression of cancer.

Although the study specifically targeted breast cancer, it's hard to believe other cancers are not similarly affected. Other studies suggest that the problem may be that the hormone melatonin, which slows the growth of cancers and boosts the immune system, is produced by the body only in darkness.

Apparently what matters most is light received through the eyes, rather than that falling on the rest of the body, as breast cancer afflicts blind women at half the rate of those who can see. I would like to see more details of that statistic, specifically how the cancer rate varies among different causes of blindness. When the fault is in the brain, is the protective effect the same as when the problem is directly with the eyes?

Similarly, I'd like to know what variations there are among people who live in different lattitudes, those who have about the same hours of daylight throughout the year, and those whose light and dark patterns vary widely with the seasons. Assuming there are enough people without artificial light to study, that is.

Although other studies indicate the problem is with light itself, the effect of artificial vs. natural light is not clear. One article suggested that lighting manufacturers should develop more natural lighting, but if the problem is light stopping melatonin production, that won't help.

I wonder what this says to those of us who stare at computer screens much of the time? And what about the common practice of putting night lights in children's rooms?

The article linked above made the following suggestions for mitigating the problem:

I notice they don't suggest reordering our lives along more natural lines, probably because for most folks such a change would be close to impossible. It's worth thinking about what is possible, however, because of studies indicating that night shift workers are significantly more likely to develop breast cancer, as are women who stay up late two or three times a week. (The article, unfortunately, did not define what "staying up late" means.) It would be irresponsible to conclude that what is true of breast cancer is true of other cancers, but even more irresponsible, risky, and foolish to assume that it isn't.