Alois Kolar
Health researcher Colleen M. Story presents the facts on artificial light that you need to know in today's article, 21.04.2015 Article by Colleen M. Story When I first arrive for vacation, me being a night owl, I buck the current. I write, read, or star gaze until around midnight or one o’clock in the morning. By about the third night, though, I start getting tired around eleven-thirty, and usually by the time I have to return to the real world, I’m used to going to bed not long after sunset. Our bodies and minds are meant to wake and sleep with the light of the sun. The invention of artificial light allowed us to alter those cycles, mostly to our benefit, but recent research has raised some concerns. It seems too much artificial light can mess up our natural sleep and wake cycles, and affect hormone production. Recent studies have even suggested that overexposure may have ties to dermatitis, eye damage, and serious diseases like cancer and diabetes. Could it be that our lights are making us sick?
Too Much Artificial Light May Increase Risk of Cancer
The light bulb was invented in 1879. Now, over a century later, there are many places in the world where humans live in almost a constant state of illumination, and children grow up unable to see the Milky Way at night. We’ve enjoyed benefits like increased productivity, protection from crime, and the ability to extend our leisure hours. But as time goes on and we use more and more light later and later into the evening, we’re also potentially putting our health at risk. Exposure to too much light at night disrupts our natural circadian rhythms, and suppresses excretion of melatonin—the hormone that regulates sleep and wake cycles. As a result, we don’t sleep as soundly, or as long, which can lead to significant health problems. Research is also finding that suppressing melatonin may have other risks as well—some tied to cancer. Back in 2001, a couple of studies came out that suggested shift work could increase risk of cancer. The first looked at about 800 participants aged 20 to 74 years who were diagnosed with breast cancer between 1992 and 1995. These were matched against controls in the same age groups. Results showed those who did not sleep during the period of night at which melatonin levels were highest were more at risk for breast cancer. The graveyard shift, in particular, was associated with a higher risk that continued to increase the longer the participants stayed on that shift. That same year, another study looked at women from the Nurses’ Health Study who worked night shifts during 10 years of follow-up. They found women who worked 1–14 years or 15–29 years on rotating night shifts had an increased risk of breast cancer compared to women who didn’t work night shifts. The women worked the shifts at least three nights per month, in addition to days and evenings in the same month. A few years later, in 2005, the scientific journal Cancer Research published the results of an animal study showing that artificial light stimulated the growth of human breast tumors by suppressing levels of melatonin. They also found that increased periods of nighttime darkness slowed the growth of these tumors. Indeed, there seems to be a connection between suppressed melatonin levels and a potential increased risk of cancer. Artificial light not only keeps us awake by reducing melatonin levels, but that the reduction could disrupt other processes in the body, allowing cancer cells to take hold. “Evidence is emerging that disruption of one’s circadian clock is associated with cancer in humans,” said lead researcher David Blask, M.D., Ph.D, “and that interference with internal timekeeping can tip the balance in favor of tumor development.” In 2007, the International Agency for Research on Cancer issued a press release announcing that after reviewing the evidence, their expert working group concluded that shift work that “involves circadian disruption is probably carcinogenic to humans.”
Too Much Light Tied to High Blood Pressure, Diabetes, and Obesity
Researchers have continued to find a connection between overexposure to artificial light and cancer over the years—and lately, they’ve broadened the link to include other diseases like obesity, diabetes, and depression. In 2010, for example, Reiter et al. found that the disruption of circadian rhythms, a lack of adequate sleep, and the suppression of melatonin aggravated weight gain, and were potential contributors to our current obesity epidemic. In 2011, researchers found that exposure to electrical light between dusk and bedtime strongly affected melatonin levels, which in turn, could affect the body’s ability to regulate temperature, blood pressure, and glucose levels. For the study, they took blood samples from over 100 volunteers aged 18–30 years who were exposed to room light or dim light in the eight hours before bed for five days. Results showed that those exposed to room light before bed had melatonin appear in their bloodstream about 90 minutes later than those exposed to dim light. Participants who left lights on during sleep had melatonin levels suppressed by greater than 50 percent. “Our study shows that exposure to indoor light has a strong suppressive effect on the hormone melatonin,” said lead researcher Joshua Gooley, Ph.D. “This could, in turn, have effects on sleep quality and the body’s ability to regulate body temperature, blood pressure, and glucose levels.” In 2013, researchers reported that exposure to artificial light at night provoked depression-like changes in animal participants, and that these changes were reversed when the light was removed. More recently, in March 2015, researchers published another study asserting that modern life, with all its reliance on artificial light, could be putting us at risk of cancer, obesity, diabetes, and other health issues. Scientists assert that there is inadequate natural light during the day inside buildings to promote optimal circadian rhythms, and too much light at night for our systems to sense true dark. “This results in circadian disruption and alters sleep/wake cycle,” the researchers write, “core body temperature, hormone regulation and release, and patterns of gene expression throughout the body.” Blue Light and Technology We can’t talk about how light is affecting our health without talking about technology. All of our gadgets, including computers, laptops, tablets, and smart phones, emit a powerful blue light that has been found to be particularly disruptive to melatonin levels. A 2009 study, for example, reported that participants who wore blue-blocking glasses for three hours before sleep experienced improved sleep quality and improved mood when compared to control subjects who wore yellow-tinted glasses that blocked ultraviolet light only. An earlier 2006 study also noted that the circadian clock is most sensitive to blue light (which comes in short wavelengths). They gave some of participants orange lens glasses that blocked blue light (called “blue blockers”), while the others received gray lens glasses. They then exposed all participants to 60 minutes of bright light between one o’clock and two o’clock in the morning. Those wearing the blue blockers were protected from melatonin reduction, while those wearing the gray lenses experienced a 46 percent reduction in their melatonin levels. The results hold when we look at the effect of our gadgets on our circadian rhythms and melatonin levels. In 2013, researchers reported that self-luminating displays (like those in tablets and cell phones) “emit optical radiation at short wavelengths, close to the peak sensitivity of melatonin suppression.” Another study a year earlier found that a two-hour exposure to electronic devices caused melatonin suppression by about 22 percent. In 2015, researchers compared the effects of reading a regular book with those of reading an electronic book, or e-reader in the hours before bedtime. They found that participants using the e-reader took longer to fall asleep, had reduced evening sleepiness, secreted less melatonin, experienced circadian rhythm disruptions, and were more likely to be sleepy the next morning than those who read a regular, printed book. Change is Coming? In 2012, the American Medical Association officially recognized the growing evidence of health problems associated with exposure to artificial light, and voted to accept the recommendations of a report from the AMA Council on Science and Public Health. Their action opened the door to additional research on the issue, as well as to education programs that will increase awareness, and to the development of new technologies that reduce the health risks of indoor and outdoor lighting. In the meantime, there are a number of things you can do to reduce your exposure to artificial light.
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Wednesday, April 22, 2015
TOO MUCH ARTIFICIAL LIGHT MAY INCREASE CANCER
