In recent years, there has been a push in building awareness among the general public with regards to blue light. Many established brands have pushed for blue light filters in their lenses to filter out blue light. Is this just a marketing gimmick to push out new products? Or is there a legitimate reason why this trend exists today?
What does blue light do?
Our main source of light, the sun, consists of a spectrum of colours namely: red, orange, yellow, green, blue, indigo and violet. Each individual colour has its own wavelength and energy, hence allowing us to distinguish them.
There are seven colours of light, so why is blue light being singled out?
Research has shown that blue light plays a role in managing our biological clock, known as the circadian rhythm. The circadian rhythm is regulated by the hormone, melatonin. Melatonin is responsible for making us feel sleepy. Blue light stimulates a part of our brains to suppress the production of melatonin which in turn helps us stay awake during the daytime.
Does blue light cause digital eye strain?
Artificial lighting and digital devices such as computers, smartphones, tablets, electronic reading devices all utilize light emitting diodes (LED) for illumination. Light emitted by LED sources has a higher proportion of blue light than any other light source. It is extremely difficult to avoid digital screens these days as we literally carry one around (for example, our smartphones) and use these devices on a daily basis.
Our exposure to blue light has been on the rise as we shift towards using energy saving lights in our efforts to go green and as digital devices become more pervasive in our daily lives. Spending long hours on our devices without taking breaks has led to a condition called digital eye strain [silo to article].
You have probably seen or been exposed to blue light blocking lenses at some point, marketed to reduce the symptoms of digital eye strain. Although, it is said that blue light causes slightly more glare and possible fatigue than other colours of light, there is limited evidence that supports that digital eye strain is caused by blue light emitted from these devices.
Several research studies have demonstrated that using several blue light filters that filter up to 99% of blue light emitted from a tablet was no more effective at reducing symptoms of digital eye strain than a neutral density filter (a filter that reduces the amount of light passing through the lens without affecting the colours of the image).
Is blue light actually harmful?
There have been claims that blue light causes retina damage. Animal studies have shown that blue light can cause changes to rabbit and mouse retina through various mechanisms. It is extrapolated from these research data and assumed that excess quantities of blue light may be detrimental to the human retina as well. However, there is no conclusive evidence from research that documents human retina damage by blue light. One thing is for certain, our office and home settings are very different from laboratory settings. Hence, our exposure to the amount of blue light from our many LED light sources is not comparable to the amount that these animals were subjected to. Regardless, there is no harm to err on the side of caution and try to limit excessive blue light exposure to our eyes.
It is unscientific to equate all blue light as harmful. Some blue light is required to regulate normal circadian rhythms and prevent development of myopia. Depriving ourselves of blue light has also been shown to be associated with depression-like changes in the brain. If you have been fortunate enough to experience life in winter overseas, you would know that days are much shorter and it could be dark around 3pm. So it’s no surprise that these countries witness an increase in cases of seasonal affective disorder (SAD) at the start of fall that continues to early Spring.
As with most things in life, blue light exposure should be kept within moderate amounts. Most normal digital displays present minimal risks as the blue light emittance is within standard acceptable range; however this is only a conclusion with respect to short-term exposure. If long-term exposure is necessary, additional anti-blue light measures would be encouraged.
Although we do not have conclusive proof of retinal damage by blue light, research has shown that exposure to blue light can disrupt the normal sleep cycle. Several research trials have demonstrated that by reducing the amount of blue light through blue light blocking lenses lead to better sleep quality in individuals suffering from insomnia. Having insufficient rest can lead to a myriad of health conditions such as increased risk of diabetes, heart disease and obesity. Therefore, it is recommended to reduce the use of digital devices, especially 1 to 2 hours before you go to bed for better sleep.
How effective are currently available blue-light-blocking lenses in reducing the effects of blue light?
Blue-light blocking lenses block between 20% to 90% of blue light, depending on the quality of the lens. We do need a certain amount of blue light for health reasons and we should not aim to filter out 100% of blue light. Such blue light lenses are helpful in reducing the amount of blue light exposure especially for people who are getting prolonged exposure to digital screens (staring at their screens for the whole day). It is less critical for people who have little to moderate exposure to digital screens.
Other than reducing screen time and using blue-light-blocking lenses, can we do anything else to reduce the effects of blue light?
We can use blue-light blocking filters that are put in front of our computer screens or phone screens. Alternatively, many devices also have a night mode setting that minimizes the amount of blue light in the evenings. When these settings kick in, the colours on screen often change to a warmer tone – usually a yellowish orange shift. This shift is dependent on how aggressive the blue light filtering is as determined by your settings. In this way, we are reducing the blue light coming from our digital screens while maintaining good exposure to natural blue light from the sun.
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