Effects of blue light technology

The effects of blue light technology refers to blue wavelengths that are commonly emitted by electronic screens. These blue wavelengths are helpful during the day when they increase attention and boost one’s mood; however, exposure to blue light in the hours before bedtime can lead to insomnia because the brain has difficulty shifting into sleep mode.

As of 2018, according to the Pew Research Center, 77 percent of American adults owned a smartphone. About half owned a tablet computer and one in five owned an e-reader device, while 73 percent owned a desktop or laptop computer. Many teenagers spend six or more hours a day on the devices, and it is not uncommon for children as young as six to have a smartphone. The increasing availability and prevalence of electronic devices has led to greater interest in the effects of blue light technology. Research has indicated that blue light exposure may contribute to health problems including cancer, diabetes, heart disease, and obesity.

Background

The human body is ruled by circadian rhythms. These rhythms typically run on a twenty-four-and-one-fourth-hour cycle, with slight shifts for night owls (whose cycles run longer) and early birds (whose cycles are typically shorter than twenty-four hours). The human body’s internal clock is guided by the presence or absence of light. For thousands of years, humans were active during the daylight hours and in the evening and night—when the world was dark—they slept. This changed when humans gained the use of fire. With the development of modern electricity, they could work through the night if they wished.

Natural sunlight contains a wide spectrum of visible and ultraviolet rays. Light rays have varying wavelengths. Those in the red end of the visible light spectrum have longer wavelengths and less energy, while waves on the blue end of the spectrum have shorter wavelengths and more energy. Blue light is visible light ranging from 380 to 500 nm (nanometers) in length, while red light waves may be as long as 700 nm. This means that about one-third of visible light is high-energy visible (HEV) light, also known as blue light. HEV light is the reason the sky looks blue. These short wavelengths are easily scattered when they encounter particles in the atmosphere.

People are exposed to blue light in sunlight, fluorescent and LED lighting, and devices such as flat-screen televisions, smartphones, electronic notebooks, and computer screens. While the sun emits much more blue light than electronic devices, people typically spend a great deal of time using their electronics and holding them close to their face, often well into the evening. And the human eye does not block blue light the way it does UV radiation; almost all blue light waves reach the retina. Too much exposure to blue light has been found to damage cells in the retina. This may increase the risk of a condition called macular degeneration, which can lead to permanent vision loss.

Overview

Exposure to blue light can cause a number of problems. Many individuals who are exposed to HEV through electronic devices experience digital eye strain. This strain is due to the short wavelengths. Because they are easily scattered, the blue wavelengths force the eye to work harder to focus. Blue light exposure within one to two hours of bedtime can have the effect of convincing the brain that the day is not over. This can prevent the mind from winding down and preparing for sleep and may lead to insomnia.

While blue light can cause problems, it is also essential to health. HEV light increases energy and alertness. It is also important to mental and emotional health because it boosts one’s mood. Individuals affected by a type of depression called seasonal affective disorder, or SAD, are often treated using light therapy. SAD typically affects people during the winter, when the days are shorter and they are exposed to less natural sunlight. Lights used to treat SAD are bright white and emit a large amount of HEV blue rays.

Exposure to blue light during the day also helps to regulate one’s circadian rhythm. Blue light increases alertness because the body perceives it as daylight and time to be active. Blue light inhibits the production of melatonin, a hormone that regulates cycles of sleep and wakefulness. When the eyes are exposed to blue light into the evening, the brain continues to function as if it is day. This causes the body’s circadian rhythm to extend beyond a twenty-four-hour day. The resulting sleeplessness may lead to fatigue during the day.

While any light can affect the body’s sleep-wake cycle, blue light is particularly powerful. A Harvard University study compared subjects exposed to 6.5 hours of blue light with a group exposed to 6.5 hours of equally bright green light. They found that the blue light inhibited melatonin production for about twice as long as the green light did. The circadian rhythms of the blue light group were shifted by three hours, while the green light group’s cycles shifted by one-and-a-half hours.

Manufacturers have developed blue light filters for many devices as a way to reduce the effects of blue light exposure. Blue light filters are available for computer screens, smartphones, and tablets, for example. Individuals may also purchase computer glasses or have blue light filters applied to prescription eyewear. Ordinary sunglasses with orange-tinted lenses also block blue light, as well as other colors although this makes them impractical for indoor use at night.

The shift toward energy-efficient lighting may affect individuals as well. Incandescent light bulbs, which were commonly used until North American governments began to phase them out in 2014, produce less blue light than modern LED and fluorescent light bulbs. Fluorescent bulbs can be manufactured with a coating inside to reduce the amount of blue light they emit.

Researchers suggest that individuals take steps to reduce the effects of blue light technology. They should avoid looking at bright screens, such as smart phones and tablets, for two to three hours before bedtime. Night light bulbs should be replaced with dim red lights, because red light has the least effect on melatonin production and circadian rhythm. Those who work night shifts or use electronic devices at night might benefit from wearing glasses that block blue light, installing apps that filter blue and green wavelengths, or dimming the brightness of screens. Individuals should also ensure that they expose themselves to bright light during the day to boost mood and alertness and improve one’s chances of sleeping well at night.

Bibliography

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“Blue Light Has a Dark Side.” Harvard Health Publishing, 12 Aug. 2018. www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side. Accessed 1 Apr. 2019.

Bradford, Alina. “How Blue LEDs Affect Sleep.” LiveScience, 26 Feb. 2016, www.livescience.com/53874-blue-light-sleep.html. Accessed 1 Apr. 2019.

Heitling, Gary. “Blue Light: It’s Both Bad and Good for You.” All About Vision, Nov. 2017, www.allaboutvision.com/cvs/blue-light.htm. Accessed 1 Apr. 2019.

“Mobile Fact Sheet.” Pew Research Center, 5 Feb. 2018, www.pewinternet.org/fact-sheet/mobile/. Accessed 1 Apr. 2019.

Schmerler, Jessica. “Q&A: Why Is Blue Light Before Bedtime Bad for Sleep?” Scientific American, 1 Spt. 2015, www.scientificamerican.com/article/q-a-why-is-blue-light-before-bedtime-bad-for-sleep/. Accessed 1 Apr. 2019.

Tosini, Gianluca, Ian Ferguson, and Kazuo Tsubota. “Effects of Blue Light on the Circadian System and Eye Physiology.” Molecular Vision vol. 22 61–72. 24 Jan. 2016. www.ncbi.nlm.nih.gov/pmc/articles/PMC4734149/. Accessed 2 Apr. 2019.

Vimont, Celia. “Should You Be Worried About Blue Light?” American Academy of Ophthalmology, 24 Aug. 2017, www.aao.org/eye-health/tips-prevention/should-you-be-worried-about-blue-light. Accessed 2 Apr. 2019.