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Column: Health hazards of artificial lighting

by Janine Wesley
| October 29, 2009 12:00 AM

Would you have ever thought that artificial lighting – known simply as “AL” – could be considered harmful? Many hidden problems arise from improper or over-exposure to AL.

The vast array of health problems include breast cancer, prostate cancer, headaches, fatigue, stress, anxiety and depression, inflammation, suppressed immune system, heart disease, diabetes, high blood pressure and even a decrease in sexual function.

Scientists believe the common link is melatonin, also referred to as “the hormone of darkness.” Made by the pineal gland, which is located in the center of the brain, it is also known to help prevent the formation of tumors. It’s manufactured mostly at night, peaks in the middle of night then tapers off, and is reduced drastically in the presence of light, (particularly in the blue part of the spectrum – mostly used by computer screens and fluorescent bulbs, etc.).

Changes in light exposure, such as sleeping with a light on, staying up late or let’s say a transatlantic or midnight flight on an airplane resulting in “jet lag,” cause a disruption of our circadian rhythm or our “biological clock,” and affects melatonin production as well as other metabolic processes in our bodies.

Shift workers are particularly at risk, because of their obvious over-exposure to excessive or bad AL. The World Health Organization announced in December 2007 its decision to classify shift work as a “probable human carcinogen.”

However the problem is not just a “shift workers problem,” it’s everyone’s. For instance, any woman (or man – men can get breast cancer, too) who lives in a community that has numerous street lamps, signs or other AL lighting sources might be at risk for higher rates of breast cancer.

The journal, “Chronobiology International,” reported a new study finding breast cancer occurrence is approximately 73 percent higher in communities with the greatest amount of AL at night than in communities with the least.

Professor Charles Czeisler of the Harvard Medical School said, “If light were a drug, the government would not approve it.”

Professor George Brainard of the Thomas Jefferson University in Philadelphia stated “Humans evolved on a planet without electric light over thousands and thousands of generations.  The body is designed to be alert and awake during daytime hours and to sleep at night. Now we have a 24-7 society that isn’t in harmony with our biological design.”

For more information go to: and reference “Reports and Studies”; (light pollution science); or (National Geographic Magazine – search “light pollution”).

(Janine Wesley is a member of a small group from Libby concerned about light pollution and its negative impact on the community at large and the environment.)