Red Light, Green Light, Blue Light?

Tosini, G., Ferguson, I., & Tsubota, K. (2016). Effects of blue light on the circadian system and eye physiology. Molecular vision, 22, 61–72.

The technology revolution during the late 20th century spurred a plethora of advancements, one of which was lighting. Although lighting has typically been static to change, in the past few decades, we’ve seen rapid progress. For example, incandescent bulbs that produce light from heat have been replaced by fluorescent lamps that utilize electron particles. There have also been advancements to light-emitting diodes, or LEDs, which emit light when a current flows through. These LEDs evolved with electronics as their small size made it ideal for use in products such as tablets and smartphones. The most common color of LEDs tends to be white, which can degrade quickly to light-emitting substances called phosphors. This prevents the LEDs from absorbing blue light, resulting in human exposure. Blue light has demonstrated negative effects on human development and physiology, specifically with cells in the eyes and circadian rhythm.

Specific cells in the eyes called photoreceptors are light-sensitive and facilitate the formation of images in our mind. Research has demonstrated that although these photoreceptors are crucial for vision, they don’t play a role in the circadian rhythm, or the internal clock of the brain. Rather, this responsibility goes to a pigment called melanopsin that is active within the wavelengths of 460-480 nm. Because melatonin, the hormone released in response to darkness, is suppressed at a wavelength at 460 nm, melanopsin is likely a key player in inhibiting the production of melatonin. Blue light is actually active at wavelengths around 460 nm, and is capable of altering the circadian rhythm more effectively than other colors of light at longer durations and higher intensity. Studies have also demonstrated that blue light can stimulate cognitive function and increase a person’s alertness of their surroundings. 

Experimentation has also demonstrated that blue light can cause significant damage to the retina, or the layer of cells in the eye that captures light and creates images. This type of light-induced damage is typically from a photochemical change where the eyes are exposed to a specific wavelength of light that can kill the eye’s cells. Excessive blue light exposure causes the production of reactive oxygen molecules that accumulate and impact cells’ functions. For example, they can build up certain pigments that affect the viability of photoreceptors. These pigments become toxic when exposed to blue light, resulting in further damage to the retina. Adding on, it seems that blue light is the only color that is capable of producing such negative consequences for the eyes. 

Though blue light has been correlated with damage to the circadian rhythm and the retina, there is limited evidence supporting blue light’s relationship with age-related macular degeneration, a disease where a person loses their central vision, causing blurred sight and blind spots. While some researchers have found that blue light can cause age-related macular degeneration, other studies found no correlation. 

All in all, the blue light emitted by cell phones poses a negative effect on the human body. Sleep schedules and eye health are heavily impacted. To prevent these ramifications, people should limit cell phone use or utilize a blue light filter to limit further damage. 

By Brenton

Citations:

Thomas, C. J., Mirza, R. G., & Gill, M. K. (2021). Age-Related Macular Degeneration. The Medical clinics of North America, 105(3), 473–491. https://doi.org/10.1016/j.mcna.2021.01.003

Zang, J., & Neuhauss, S. C. F. (2021). Biochemistry and physiology of zebrafish photoreceptors. Pflugers Archiv : European journal of physiology, 473(9), 1569–1585. https://doi.org/10.1007/s00424-021-02528-z