What Is Blue Light?

by Diane Jen Baliling

Art by Ewemiz Insigne for Hiraya Zine

Light Has a Dark Side Too!

Billions of people around the world have been ordered to stay at home to help curb the coronavirus pandemic. As a result of the strict protocol of ordering us to limit our movement, it has triggered an unprecedented demand for digital dependency and our focus on our devices has tripled! This could be detrimental to the health of many as they shift to the new normal.

Having to focus more on our devices means our eyes absorb more of the blue light of which our devices project or show. Devices emit much stronger blue light than we get from the sun. According to research from RescueTime, people generally spend an average of 3 hours and 15 minutes on their phones every day, with the top 20% of smartphone users spending four and a half hours. Spending hours staring at a screen can cause dryness, fatigue, and eye damage.

Squandering time on devices until late at night tricks your body into thinking that you should be awake. Due to the high energy waves absorbed by the cornea, the eyes’ outer layer, blue light goes straight through and slowly deteriorates the retina.

What is Blue Light?

Blue light is a type of light from the visible range of the electromagnetic spectrum that forms the white light we get from the sun together with the other colors: red, orange, yellow, green, indigo, and violet. Beyond this range, we have the ultraviolet or UV light, which are not visible to humans but are perceivable to some animals, such as birds, bees, and certain fish.

Each color has a different wavelength. Red has the longest wavelength, while violet has the shortest wavelength. Ultraviolet light, which have wavelengths and energies that are too high for human eyes to see, are called such because they are beyond the violet of the spectrum. Some animals can see ultraviolet light because they have visual ranges which include these wavelengths.

Illustration by Leah Hustak from NASA’s James Webb Space Telescope.

Because energy increases with decreasing wavelengths, blue light is considered one of the highest intensity types of visible light. Computers, tablets, smartphones, and other digital devices including fluorescent, LED light bulbs and flat-screen TVs emit significant amounts of blue light. LEDs are everywhere because they consume less power than rival technologies and are cheaper to produce. However, our bodies’ aren’t in favor of these sources.

Hasty Conclusions?

But do you know why blue light is harmful? Are you aware of its side effects?

To those who raised their eyebrows knowing not all blue light is bad, you may be right.

Blue light is everywhere, which means it’s in the sunlight. When sunlight reaches Earth’s atmosphere and is scattered in all directions by gases and particles in the air, blue light is scattered more than the other colors because it travels with shorter wavelengths (approximately 380nm and 500nm) which makes the sky blue.

Your body uses this blue light from the sun to cue you the difference between day and night to work your biological clock and regulate your sleep cycle. It is basically what keeps you awake during the day.

However, it can severely affect the quality of your sleep if you use too much of it at night.

Blue light from a tablet in use at night. Photo by Blue Light Exposed.

Research has also found that exposure to more blue light at night suppresses the production of the sleep hormone melatonin more than any other type of light. Melatonin is a hormone that your brain produces in response to darkness. It helps with the timing of your circadian rhythm (24-hour internal clock) and with sleep. Being exposed to too much light at night can block melatonin production and being exposed to blue light is just worse. Lack of melatonin was repeatedly reported in patients with coronary heart disease, cancer, diabetes, and clinical depression.

A big reason why you want to avoid blue light at night is because of its cortisol-stimulating and melatonin-suppressing effects. Just as light can suppress melatonin, it can also increase cortisol. The imbalance of these two hormones in your system can lead to negative impacts on your health over time.

What to do moving forward

For one thing, some manufacturers now sell special glass screen protectors that stop the blue light from reaching your eyes and causing damage to your retina. At a microscopic level, this glass has tiny ridges that block blue waves and let the other less harmful light go through these glasses. A study shows they can block up to 60% of blue light and 99% of UV rays. Many users have also reported that their sleeping patterns were significantly improved after only a few days.

A phone with the blue light filter off (left) and a phone with the blue light filter on (right). Photo by Pixel Spot.

Some of our devices are also equipped with a blue-light filter, night light, night mode, or dark mode, which you can choose to switch during the night time to further protect your eyes. You can also buy eyewear or blue-light glasses that you can use for all blue light-emitting devices—but beware of fake eyewear! Lots of cheap but fake blue-light glasses have popped up on various platforms since the start of the pandemic. The real ones may cost you, but acquiring fake eyewear can lead to further damage and negative consequences.

Make sure that you also keep watch for the unseen damage that your day-to-day gadgets can do to your health. You may build a routine of using a blue-light shield or control eyewear two hours before sleeping. You must take note that blue-light is essential during the day, and you must not block all of it.

Gadgets now hold great importance in everyday life. Mobile phone and internet usage have become universal practices, especially among the student community since our shift to online learning. While gadget usage can have both pros and cons, our devices aren’t as harmless as we think they might be. We only need to be more aware of their effect on our personal health and make changes to protect our eyes. After all, the prevention is better than the cure.


Contributions by Mary Liv Licardo

#ARCHIVES: This article was previously published in Hiraya Zine Volume 1, Issue 2: Science for Society last September 2021. Download the zine for free here.



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