Will Somebody Please Turn Off the Lights?

Thursday Apr 16 | BY |
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modern city at night

Too much artificial light has been linked with obesity, diabetes, and cancer.

I spend about two weeks each year on the Pacific Coast, in a little fishing town that for all intents and purposes, shuts down about nine o’clock every night. Maybe ten on weekends.

Drive through town after that and you’ll see a lot of empty sidewalks and dark buildings. Even the bay lies still and quiet.

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.

  1. Get outside: Expose yourself to natural light for at least an hour every day. Try a morning jog, lunchtime walk, or after-work activity that gets you out into the sun. The more natural light you get during the day, the easier it will be to sleep at night.
  2. Turn off the lights: At least an hour before bedtime, dim the lights and turn off the television and all technological gadgets. For optimal results, avoid looking at bright screens starting two-to-three hours before going to sleep.
  3. Keep the gadgets out of your bedroom: If you wake up and immediately check your phone, you’re disrupting your circadian rhythms and are likely to feel tired the next day. Over time, these effects could have more serious health consequences. Keep all gadgets out of your room.
  4. Choose a real book: If you’re going to read before bed, you’re better off reading a real book than an e-reader, to save yourself from the exposure to bright, blue light. Dimmer light with a more reddish tinge, like an incandescent bulb, is friendlier to your circadian rhythms.
  5. Copy the pilots: Pilots have red lights to illuminate their instrument panels at night. They’re easier on the eyes, and it turns out red is the least able to affect your melatonin levels. Look for dim red lights to use at night. Your alarm clock, for instance, is better if it emits red rather than blue light.
  6. Consider orange shades: Research has found that orange-tinted, blue-light-blocking lenses can block blue light—the most disruptive to melatonin levels. Shift workers and night owls may be able to reduce the damage by wearing these when possible. (Simply Google “blue-blocking glasses” to find a pair.)
  7. Watch where you place the LEDs: LED lights, though more energy efficient, produce more melatonin-disrupting blue light than the old fashioned incandescent bulbs. A recent report by ANSES, the French Agency for Food, Environmental and Occupational Health & Safety, also raised concerns that LED lamps can cause stress to the retina of the eye because of the excessive blue light.
  8. There’s an app for that: If you most work on your gadgets at night, try software like f.lux, which adapts the colors and light level on your screen to the time of day or night.
  9. Brush your teeth in dim light: Remember that even brushing your teeth under bright lights may affect your readiness to sleep. Try to install a red light in the bathroom or brush with the dimmer switch on.
  10. Darken your room: If you have light coming into your room during your sleeping hours, do something to correct it. Try dark, heavy drapes or other ways to block the light out.

Do you have other ways to reduce your exposure to artificial light? Please share them with our readers.

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Scott Davis, et al., “Night Shift Word, Light at Night, and Risk of Breast Cancer,” J Natl Cancer Inst 2001; 93(20):1557-1562, http://jnci.oxfordjournals.org/content/93/20/1557.abstract?ijkey=5c7533c6ad6efcbfdd1a9d2d5a0a3c311f5b05b6&keytype2=tf_ipsecsha.

Eva S. Shcernhammer, et al., “Rotating Night Shifts and Risk of Breast Cancer in Women Participanting in the Nurses’ Health Study,” J Natl Cancer Inst, 2001; 93(20):1563-1568, http://jnci.oxfordjournals.org/content/93/20/1563.abstract?ijkey=8522777aa4cf58b0915363dd55297c3ea481530d&keytype2=tf_ipsecsha.

National Institute of Environmental Health Sciences, “New Research Shows Artificial Light at Night Stimulates Breast Cancer Growth in Laboratory Mice,” National Institutes of Health, December 19, 2005, http://www.nih.gov/news/pr/dec2005/niehs-19.htm.

Russel J. Reiter, et al,. “Obesity and metabolic syndrome: Association with chronodistruption, sleep deprivation, and melatonin suppression,” Annals of Medicine, September 2012; 44(6):564-577, http://informahealthcare.com/doi/abs/10.3109/07853890.2011.586365.

Richard G. Stevens, Yong Zhu, “Electric light, particularly at night, disrupts human circadian rhythmicity: is that a problem?” Philisophical Transactions B, March 16, 2015, DOI: 10.1098/rstb.2014.0120, http://rstb.royalsocietypublishing.org/content/370/1667/20140120.

Gooley JJ, et al., “Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans,” J Clin Endocrinol Metab, March 2011; 96(3):E463-72, http://www.ncbi.nlm.nih.gov/pubmed/21193540.

“IARC Monographs Programme finds cancer hazards associated with shiftwork, painting, and firefighting,” December 5, 2007, [Press Release], http://www.iarc.fr/en/media-centre/pr/2007/pr180.html.

Ron Chepesiuk, “Missing the Dark: Health Effects of Light Pollution,” Environ Health Perspect. January 2009; 117(1):A20-A-27, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2627884/.

Chris DeFrancesco, “AMA: Health Implications of Light at Night ‘Serious,’” UConn Today, June 20, 2012, http://today.uconn.edu/blog/2012/06/ama-health-implications-of-light-at-night-serious/.

Anne-Marie Chang, et al., “Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness,” PNAS, January 27, 2015; 112(4):1232-1237, http://www.pnas.org/content/112/4/1232.full.pdf.

TA Bedrosian, et al., “Chronic dim light at night provokes reversible depression-like phenotype: possible role for TNF,” Molecular Psychiatry, August 2013; 18 (8):930-936, http://www.ncbi.nlm.nih.gov/pubmed/22824811.

Tim Whitaker, “Light and human health: LED risks highlighted,” LEDs Magazine, http://www.ledsmagazine.com/articles/2010/11/light-and-human-health-led-risks-highlighted.html.

Burkhart K, Phelps JR, “Amber lenses to block blue light and improve sleep: a randomized trial,” Chronobiol Int., December 2009; 26(8):1602-12, http://www.ncbi.nlm.nih.gov/pubmed/20030543.

Sasseville A, et al., “Blue blocker glasses impeded the capacity of bright light to suppress melatonin production,” J Pineal Res., August 2006; 41(1):73-8, http://www.ncbi.nlm.nih.gov/pubmed/16842544.

Wood B, et al., “Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression,” Appl Ergon., March 2013; 44(2):237-40, http://www.ncbi.nlm.nih.gov/pubmed/22850476.

Rebekah Mullaney, “Light from Self-Luminous Tablet Computers can Affect Evening Melatonin, Delaying Sleep,” Renssalaer Polytechnic Institute, August 27, 2012, http://news.rpi.edu/luwakkey/3074.

David Blask, et al., “Light Pollution: Adverse Health Effects of Nighttime Lighting,” Report 4 of the Council on Science and Public Health, http://www.atmob.org/library/resources/AMA%20Health%20Effects%20Light%20at%20Night.pdf.

Colleen M. Story

Colleen M. Story

Colleen M. Story, a northwest-based writer, editor, and ghostwriter, has been creating non-fiction materials for individuals, corporations, and commercial magazines for over 17 years. She specializes in the health and wellness field, where she writes and ghostwrites books, e-books, blogs, magazine articles, and more.

Colleen is the founder of Writing and Wellness. Her fantasy novel, “Rise of the Sidenah,” was released with Jupiter Gardens Press in September 2015. Her literary novel, “Loreena’s Gift,” is forthcoming in spring 2016 from Dzanc Books. She lives in Idaho. www.colleenmstory.com


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  1. zirah1 says:

    Great article and lots of helpful info. The only thing I wish had been mentioned was the specific time period melatonin production is naturally at its highest level. It just alludes to there being such a time, but I don’t think it ever said what it was.

  2. Tom Woloshyn says:

    I have been using Color Therapy for over 35 years now and use bright light to put myself to sleep at times and the color I use is most often Indigo, I do not like sleeping in a room with light in it but sleep deeply with a bright Indigo light being shone directly on me. I have used it successfully to treat many conditions for myself and others, the book
    “Healing For The Age of Enlightenment” has a whole chapter on color therapy and its application which is worth reading. My book “The Complete Master Cleanse” has a chapter on color that explains how and why it works from a very Scientific perspective, remember all food is created with light from the sun.

  3. Puan Tan says:

    Informative health related article. The suggested practical things to do are quite helpful.

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