Two thirds of light spills beyond and above such fields
In praise of Darkness
By Bill Blakemore, ABC News.com May 17, 2001
Darkness for Health
Scientists have now discovered that only when it's really dark can your body produce the hormone called melatonin. Melatonin fights diseases, including breast and prostate cancer. "It turns off the cancer cells from growing", says Joan Roberts, a photo biologist. But if there's even a little light around your bed at night, your melatonin production switches off.
Light at night may have health effects
By Katy Human, Scripps Howard News Service, January 9, 2002
A bright streetlight shining through a bedroom window may not only interrupt sleep, it may also increase the risk of cancer. Women exposed to light at night might appear to be more vulnerable to breast cancer, according to two studies published in the Journal of the National Cancer Institute. The effect is probably related to melatonin, a light-sensitive chemical produced in the brain, the authors said.
What Light Yonder Window Wreaks-Circadian Rhythms and Breast Cancer
By Sharon Batt
Breast Cancer Action, Newsletter#61-September/October 2000
It was the opening session of a workshop exploring the effect that artificial light has on breast cancer risk, and University of Connecticut epidemiologist Richard Stevens showed an aerial slide of the United States by night. Dots of white city lights twinkled against the blackness, coalescing into splotches in areas of high population density."If light were a drugm I'm not sure the Food and Drug Administration would approve it" Charles A Czeisler quipped in the Medical Tribune last year. Even tiny slivers of light at night disrupt the melatonin levels of rats, promoting tumour growth. Removing the pineal gland in rats stimulates tomour growth, and melatonin inhibits the growth of estrogen-receptor-positive (ER+)breast cancer cells in vitro by 30 to 40 percent. This leads researchers to speculate that reducing our exposure to light at night might decrease rates, and that pharmacological use of melatonin may be effective in treating cancer.
The good news is that star light, moon light, and lightning all fall outside the spectrum of light that depresses melatonin.
Does Light Have a Dark Side?
Nighttime illumination might elevate cancer risk
By J. Raloff, Science News Online Week of October 17, 1998
Exposure to light at night can disrupt the body's production of melatonin, a brain hormone best known for its daily role in resetting the body's biological clock
(SN:5/13/95, p, 300) Secreted primarily in the brain, and at night, melatonin triggers a host of biochemical activities, including a nocturnal reduction in the body's
production of estrogen. Some researchers have speculated that chronically decreasing nocturnal melatonin production-as with light-might increase an individual's risk of developing estrogen-related malignancies, such as breast cancer.
