Green building standards have focused on one thing when it comes to lighting, and that’s energy consumption. This focus is well placed, since the U.S. Energy Information Administration estimates that in 2010 lighting accounted for about 13% of total U.S. electrical consumption, but an energy-only focus leaves out important considerations regarding the health effects of artificial light. At the Department of Neurology at Jefferson Medical College in Philadelphia, George C. Brainard, Ph.D. , conducts pioneering research on the influence of modern, electrically illuminated environments on human biology and behavior, research that may result in our having to reconsider the design of residential lighting.
“Light serves as a powerful stimulus with both biological and behavioral effects in human beings. It makes sense that if light can regulate circadian and endocrine cycles, it can also deregulate these cycles and cause problems. There’s a hypothesis—and it remains just a theory in testing, but with some significant epidemiological and collateralized experimental support thus far—suggesting that circadian disruption due to artificial light exposure may represent a asast cancer risk. Suppression of melatonin secretion from the pineal gland appears to play a pivotal role in this risk,” explains Brainard.
The first suggestion that a correlation may exist between exposure to electric light and breast cancer came in 1987 when researcher Richard Stevens of the University of Connecticut Health Center noticed a markedly high incidence of breast cancer among night shift workers, and contrasted this finding with research showing a markedly lower incidence among the blind. In the end, Stevens concluded that a strong link probably exists between electrical light and the disruption of cancer-protective mechanisms in the cell, perhaps linked to melatonin.
Brainard engaged in a study that further suggested a correlation. “We exposed healthy young women to three lighting environments: broad daylight, darkness, and artificial light at night. We took blood samples after each exposure and sent these to the laboratory of David Blaskl, M.D., Ph.D., where living breast cancer cells were infused. The cancer cells grew in the blood samples taken after both daylight and bright white fluorescent light exposure at night. In contrast, tumor growth was slowed when infused with blood samples taken after exposure to darkness,” which suggests melatonin secreted during darkness may play a role in suppressing the growth of cancer cells.
In response to this research, the World Health Organization classified shift work as a “probable” carcinogen in 2007, placing shift work, which necessarily involves chronic exposure to electrical light at night, in the same category as cancer-causing agents like diesel engine exhausts. According to an article from The Associated Press, some studies imply a similar effect related to prostate cancer in men. Denmark went as far as offering indemnification to some nurses that worked night shift 20 years or longer and contracted breast cancer.
Although only 20% of the population stays up all night exposed to artificial light, all of us have extended our daily light exposure considerably beyond the normal circadian cycle, resulting in at least an epidemic of sleep deprivation, according to the Centers for Disease Control, strongly associated with an assortment of health risks from diabetes and heart disease to obesity.
Some astronauts aboard the International Space Station suffer from sleep and circadian disruption due, in part, to experiencing sunsets and sunrises every 90 minutes as ISS orbits the earth. This can result in potentially dangerous performance lapses due to lack of adequate sleep. Following a decade of research supported by the National Institutes of Health and NASA, Brainard is now working with a team of engineers, scientists,and flight surgeons toward the installation of a programmed lighting scheme scheduled for deployment in 2015-2016 on the space station. The primary goal is to provide a solid-state lighting system that is orchestrated to put out the right type of light at exactly the right time.
The quality of light has a strong relationship with its effect on biological and behavioral responses, explains Brainard, with intensity, wave length, and time of day all closely related. “The problem with our typical electrical lighting is that it comes with only two settings, on and off. We need a more natural arch of lighting throughout the course of a day, with brighter and blue-enriched lighting during the daylight hours to keep us alert, and then gradually longer wavelength-enriched lighting in the red and orange spectrum, steadily dimming in the evening.
This allows you to remain active, but it does not inhibit melatonin secretion so you can get into the right biological state for sleep.” Computer monitors, modern television screens, LED lights, and many other contemporary (often highly energy-efficient) light sources are rich in the blue spectrum that inhibits melatonin. Brainard believes that his work with NASA is already influencing R&D at certain lighting companies that will unveil residential lighting systems—versus simply light fixtures—which allow us to keep extended, productive hours without disrupting the natural circadian rhythms necessary for biological health and emotional well-being.Brainard is emphatic in clarifying that normal, residential lighting is not a health risk, but that more natural and healthful lighting systems could evolve in the near future from ongoing research into the biological and behavioral effects on humans of electric light.