The Blue Light Special
Kmart was famous for its “blue light specials.” It even brought the “blue light specials” out of retirement in the hopes of persuading disappearing customers to come back into its stores. Didn’t work. As of October 4, 2023, there are only 6 remaining US Kmart store locations still open with only 2 in the contiguous United States; Miami and Bridgehampton, Long Island, New York. There are three Kmart stores in the Virgin Islands, and one in Guam. At its zenith, Kmart had 2,486 stores. https://brostocks.com/2023/08/03/how-many-kmarts-are-left-in-the-united-states/ An omen, perhaps.
Some years ago I went into a diner for what I expected to be its “blue plate special.” I was disabused of that expectation by the waitress who pointed to the flashing blue light advertising its “blue light special.” What did I want? In Europe flashing blue lights are used for emergency vehicles. Is there a message here about what might be included in the blue light special … a warning for my stomach, perhaps.
It turns out that blue light can affect your digestion by disturbing your sleep cycles. When your sleep cycle is disturbed, your body does not produce as much leptin, a chemical that signals that your stomach is full after meals. Metabolic changes can also take place, especially blood sugar levels. Blume, C., C. Garbazza & M. Spitschan, “Effects of light on human circadian rhythms, sleep and mood,” Somnologie (Berl) 23(3):147-156 (Sep 2019). https://doi.org/10.1007/s11818-019-00215-x; Driller, M., G. Jacobson & L. Uiga, “Hunger hormone and sleep responses to the built-in blue-light filter on an electronic device: a pilot study,” Sleep Sci 12(3):171-177 (Jul-Sep, 2019). https://doi.org/10.5935/1984-0063.20190074;
We are surrounded by blue light. It does good things for us; it also does bad things to us. Blue light stimulates the parts of the brain that make us feel alert by elevating our heart rate and body temperature. During daylight hours, blue light can enhance our mental acuity and functional performance. Daylight blue light exposure can also help set us up for better sleep quality by tuning our circadian rhythms, the 24-hour cycles that signal our bodies to carry out essential functions. Historically, these rhythms were aligned with sunrise and sunset. Vandewalle, G., P. Maquet & D. Dijk, “Light as a modulator of cognitive brain function,” Trends Cogn Sci 13(10):429-38 (Oct 2009). https://doi.org/10.1016/j.tics.2009.07.004; Sollars, P. & G. Pickard, “The Neurobiology of Circadian Rhythms,” Psychiatr Clin North Am 38(4):645-65 (Dec 2015). https://doi.org/10.1016/j.psc.2015.07.003; Rishi, M., et al., “Daylight saving time: an American Academy of Sleep Medicine position statement,” J Clin Sleep Med 16(10):1781-1784 (Oct 15, 2020). https://doi.org/10.5664/jcsm.8780
Exposure to blue light in the hours leading up to bedtime can interfere with sleep by disrupting circadian rhythms and trick our brain into thinking it is still daytime. It can make us feel alert instead of tired and ready to wind down into sleep. Blue light exposure in evening hours reduces the amount of melatonin your body releases, the “sleep hormone,” also known as the “hormone of darkness.” It is the melatonin made in your pineal gland that regulates your circadian rhythm. The best natural foods for helping your sleep are kiwi, tart cherries, milk, fatty fish like salmon, mackerel, herring, tuna and sardines, nuts, whole grains, and herbal tea. Masters, A., et al., “Melatonin, the Hormone of Darkness: From Sleep Promotion to Ebola Treatment,” Brain Disord Ther 4(1):1000151 (2014). https://doi.org/10.4172/2168-975X.1000151 While we are on the subject of melatonin, it has been shown to provide relief from acid reflux, a gut issue. Kandil, T., et al., “The potential therapeutic effect of melatonin in Gastro-Esophageal Reflux Disease,” BMC Gastroenterol 10:7 (Jan 18, 2010). https://doi.org/10.1186/1471-230X-10-7
Melatonin supplementation does help with sleep. Around 6 million U.S. adults take melatonin, a five-fold increase. "Most of the times, melatonin is actually misused because it's used as a general sleep aid and to help with insomnia," says Dr. Naima Covassin of the Mayo Clinic Cardiology Laboratory. Melatonin is not a sleep promoter, rather it is a circadian rhythm regulator that helps “reset our clocks” from circadian rhythm disruption. Furthermore, people today are taking higher doses of melatonin than recommended, which can be counterproductive. "Higher doses are not necessarily more effective, and actually can be counterproductive because they can have opposite effects," she says. "They may end up making you sleepy during the day, when you don't want to be sleeping, and also increase risk of adverse effects, as well." Stiepan, D., “Mayo Clinic Minute: What to consider before using melatonin supplements for sleep.” (Feb 22, 2022). https://newsnetwork.mayoclinic.org/discussion/mayo-clinic-minute-what-to-consider-before-using-melatonin-supplements-for-sleep/; Besag, F., et al., “Adverse Events Associated with Melatonin for the Treatment of Primary or Secondary Sleep Disorders: A Systematic Review,” CNS Drugs 33(12):1167-1186 (Dec 2019). https://doi.org/10.1007/s40263-019-00680-w The bottom line is getting enough restful sleep allows your body to make the melatonin you need.
We are surrounded by electromagnetic radiation, parts of which are visible. The visible portion is how we see rainbows, the full spectrum light from the sun is refracted through rain drops. The refraction bends the wavelengths of the various colors. The longer the wave, the less energy it transmits. Blue light has very short, high-energy waves. Blue light waves are slightly less powerful that ultraviolet waves (UV). While we can enjoy the blue in a rainbow, we cannot see the UV waves that give us sunburns and can damage our eyes.
Unfortunately, our eyes are particularly sensitive to blue light. The lens and cornea of your eye protect the light-sensitive retina at the back or your eye from damaging UV rays. Blue light passes through unencumbered. The retina collects the incoming light and passes its response to that light to your brain via the optic nerve.
According to the American Academy of Ophthalmology, age-related macular degeneration (AMD) is the number one cause of loss of sight in people over 50 years of age. The macula, an oval-shaped pigmented area in the center of the retina at the back of your eyeball, is responsible for your central vision, that portion of your sight that lets you see objects directly in front of you. For example, the macula lets you tell the difference between faces and specific colors, as well as read text on a page. It is also the part of your eye that allows you to see tiny movements and small details. The macula becomes damaged as you age. Research has questioned whether blue light speeds the degradation of the macula. Melatonin has been shown to improve eye health. Poor sleep interferes with the production of melatonin in your body. Yi, C., “Effects of melatonin in age-related macular degeneration,” Ann N Y Acad Sci 1057:384-92 (Dec 2005). https://doi.org/10.1196/annals.1356.029
While the question of accelerated macular degradation remains unanswered, we today live in an environment filled with more blue light. The sun is the single largest source of blue light. Fluorescent and incandescent light bulbs emit blue light. The largest increase in blue light comes from our widespread use of devices with light-emitting diodes, computer and laptop screens, flat-screen televisions, portable devices like cell phones, tablets and eReaders. These all emit large amounts of blue light. How about virtual reality glasses that put intense blue light 3 to 4 inches directly in front of your eyes. A transitory but particularly irritating source of blue light is modern automobile headlights, which with their brighter, whiter light cause visual glare, ocular fatigue, and squinting. The overall problem with blue light exposure is the amount of time we spend in front of LED screens at close range.
Research has shown that when people use digital devices with an LED screen they blink less than usual, which reduces the amount of moisture on the eye. Digital eyestrain is generally associated with focusing. Because blue light scatters easily, your eye has to work harder to focus. The longer you stare at an LED screen the more chance of dry, sore, irritated, or tired eyes, and headaches. Jaiswal, S., et al., “Ocular and visual discomfort associated with smartphones, tablets and computers: what we do and do not know,” Clin Exp Optom 102(5):463-477 (Sep 2019). https://doi.org/10.1111/cxo.12851; Chang, A., et al., “Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness,” PNAS 112(4):1232-1237 (Dec 22, 2014). https://doi.org/10.1073/pnas.1418490112
Blue light screens have not been around long enough for research on long-term effects. However, it is clear that blue light screens, especially at night before bedtime, interfere with circadian rhythms in both adults and children. Are there or may there be longer-term effects on children’s development? We don’t know. What we do know is blue light devices have become ready pacifiers for both adults and especially children. Wong, N. & H. Bahmani, “A review of the current state of research on artificial blue light safety as it applies to digital devices,” Heliyon 15;8(8):e10282 (Aug 2022). https://doi.org/10.1016/j.heliyon.2022.e10282
We have already touched on the impact of blue light on your circadian rhythm. In disturbing your sleep cycle, you can also face an elevated risk of hormone-related cancers, such as breast and prostate. Garcia-Saenz, A., et al., “Evaluating the Association between Artificial Light-at-Night Exposure and Breast and Prostate Cancer Risk in Spain (MCC-Spain Study),” Environ Health Perspect 126(4):047011 (Apr 23, 2018). http://doi.org/10.1289/EHP1837
In today’s world we cannot get away from blue light screens; they are part of our work, our play, and our lives. We can mitigate some of the impacts of blue light from our devices. Stop every ten to twenty minutes and focus on objects further away; look outside (that’s Mother Nature out there, lots of beauty). Keep your eyes moisturized, use eye drops; a room humidifier also helps. If you need eyeglasses, make sure you have a correct prescription for screen use such as a laptop (ideally an arm’s length away). Today, most eyeglasses have a blue light reduction coating. Change the settings on your device to warmer tones, more to the reds. There are commercially available blue-light-filtering screens, although it is not clear these screens affect your sleep-wake cycle. There are also blue-blocking glasses, although their effectiveness is unclear. Smith, A., et al., “The Effect of a Screen Protector on Blue Light Intensity Emitted from Different Hand-held Devices, Middle East Afr J Ophthalmol 27(3):177-181 (Oct 30, 2020). https://doi.org/10.4103/meajo.MEAJO_2_20
You can also purchase full-spectrum light bulbs, bulbs that emit a spectrum close to natural daylight.
Perhaps the most effective antidote for reducing the effects of blue light, especially at night, was invented in the mid-1400s by Johannes Gutenberg … a book (not the e-book version).
We have spent the most time talking about the impact of blue light on circadian rhythms, specifically the impact on sleep and sleep quality. Keep in mind that sleep and sleep quality have a direct impact on your gut … and consequently your overall health.
Your choice.