What is Blue Light Filter and How Does It Work?

What is Blue Light Filter and How Does It Work?

What Is Blue Light?

Before we start talking about blue-light filters and potentially harmful blue light, we have to take a gander at physics and figure out what exactly blue light waves are. Don’t get scared – you are not going to be reliving your high school physics nightmares--we are going to simplify the science talk and get to the bottom of the issue. Here's the main things to know. 

To be able to see anything, we need to have light. Light is just a form of electromagnetic radiation which shows up in waves, both longer and shorter wavelengths that are measured in nanometers. The human eye can register wavelengths from 380nm to 740nm. Those waves form the visible electromagnetic light spectrum our brain processes, and turns waves into the wonderful colorful world we see. 

Different wavelengths translate into different colors, but when we see light, we are not consciously aware of all the different hues that enter our eyes. Our brains are conditioned to send out certain information and we don’t dwell on it unless we have to.

Blue light rays are the ones with the shortest wavelength, but they emit the most energy. Kind of paradoxical, but we should take heed, as blue light rays, or high energy visible (HEV) rays, are the ones we are exposed to much more than the others. During the day we receive plenty of them from the sun, but any artificial source of visible light will contain blue light waves. That's right, our precious iPhones, Androids, iPads, Macbooks, Samsungs, and even the Google Pixel for some of us--they all emit blue light waves. 

What Are the Effects of Blue Light?

Blue light waves regulate your circadian rhythm. During daylight hours, the sun is the number one source of blue light. Blue light is like the Energizer Bunny – it keeps you moving, it elevates your mood, enhances your memory, and boosts your cognitive functions. We need constant shots of blue light energy so we can do our best and most productive work during the day. 

Since the caveman times, we have been conditioned to stay really active during daylight hours and to go to sleep once the sun sets. The sunrise and sunset turns our circadian rhythm on and off, essentially being in charge of our sleep cycle. The dark of the night triggers our endocrine system to start producing melatonin, which is nature’s Ambien. Without melatonin, our bodies don't know it's time to sleep, and with the right amounts of melatonin, our bodies can sleep better.

Back in the day, our working day was nine to five in winter, five to nine in summer. Unless you were the unlucky one living in the north of the northern hemisphere where there were periods of night followed by twilight in the winter and unending “white nights” followed by daylight in the summer time.

Artificial sources of light also emit blue light waves, meaning blue light can affect you even after the sun goes down. It was all fine and dandy before electricity was invented. Nicola Tesla illuminated cities, which extended daylight hours (yay! for all of the would-be scholars who hovered under the blankets reading with a flashlight until the wee hours – it certainly beats candles!)

We receive more and more blue light waves from our digital devices. Enter the digital era and our addiction to our smart phones, tablets, and laptops. We might snuggle up to our beloveds or our fuzzy pets at night, but there is going to be an electronic device or two fighting for attention, offering another glimpse, or two, or three into the unknown depths of the mighty internet. We might turn our night lights off, but there is certainly going to be plenty of blue-light illuminating our faces. Even with blue light filter apps, night mode/night shift, and color temperature changes our devices have built in, evening screen time still tells our melatonin it's not time to go to work yet. 

Our sleep patterns are disrupted by extra exposure to blue light. Our inner caveman is telling us that we should retire to sleep. The sun has set hours ago, the stars are twinkling, the cicadas are chirping, melatonin is itching to burst out, but that blue light is keeping our eyes open, our minds alert, and our thoughts racing a hundred miles per hour. We are tired, but we can’t fall asleep. Our brains are tricked by the sneaky blue light emanating from our smart phones, and melatonin absent, insomnia rules.

We spend a lot of time in front of our computer screens which emit blue light. We get up drained and fatigued, and after downing a few cups of coffee to fight off drowsiness, we start our working day planted in front of a computer. Yes, you guessed it – more blue light. Your eyes are tired, flicking back and forth between images, a foot away from the screen. If you are an average office worker you are likely to spend over 1,500 hours per year staring at the computer screen. And we don’t count the time you’d spend on your smart phone after hours.

Is Blue Light Harmful? 

Blue light is high energy visible light (HEV) that reaches the retina unfiltered

Researchers and medical professionals have been pondering this question since electronics became mainstream. Our eyes are not designed to withstand prolonged blue light exposure at such a short proximity which might result in quite a few harmful effects:

  •       Disruption of the circadian rhythm
  •       Poor sleep
  •       Digital eye strain
  •       Potential macular degeneration
  •       Eventual blindness

Early research shows that blue light might cause eye strain, as reported by Prevent Blindness, a non-profit organization founded to prevent vision loss. The American Optometric Association defines digital eye strain as "a group of eye and vision-related problems that result from prolonged computer, tablet, e-reader, and cell phone use." Some of the symptoms you may experience are headaches, blurry vision, dry eyes, and neck pain.

Most of our electronic devices use LEDs, which emit a greater amount of blue light rays when compared to regular incandescent or fluorescent bulbs. All products that that have LCD screens – laptops, tablets, or older smart phones use LEDs as backlighting in their displays, and no screen filter can really block that out.

According to the American Optometric Association (AOA), extended exposure to blue light which results from staring at a computer screen for several hours, might cause macular degeneration, a significant damage to your retina (a thin innermost layer of tissue that receives light, converts it into neural signals, and sends it to the brain) - not only are they high-energy waves, but they reach the retina almost unfiltered.

What is Blue Light Filter and How Does It Work?

As blue light waves are not naturally filtered, blue light filters are specifically designed to eliminate most of the HEV blue lights from the light spectrum. It is not necessary to block out blue light waves completely, as they are mostly beneficial to us. We need them to regulate our circadian rhythm, to be more productive, and have more energy during the day.

Most blue light filters eliminate the most harmful frequencies that fall in the range between 400 and 440nm, which can help ease many of the symptoms linked with the extended use of digital devices. They still allow some blue light to come through to keep us in sync with natural day-night cycles, while helping our eyes relax and feel less strain.

Some filters, though, are designed for nighttime use and they block blue light in frequencies up to 480nm.

Nowadays, you can buy a blue light filter screen for your computer or tablet, and most newer smartphones are equipped with some form of blue light protection. If you wear prescription glasses or readers, why not invest in a pair of fashionable frames with blue light blocking lenses? Not only will you look stylish and sophisticated, but your eyes will thank you. LOOK OPTIC is a fantastic place to start, with a huge selection of blue light glasses to choose from, including computer glasses, too. 


Blue light filters can alleviate many harmful effects resulting from an extended exposure to digital devices, from blurry vision and dry eyes to digital eye strain, macular degeneration, and even blindness.  Sure, research on this topic might be in early stages, but what do you have to lose? We bet you’ll look much better in front of your computer while wearing a fashionable pair of blue light blocking glasses than squinting like Mr. Magoo, 





Previous Article

Does Blue Light Filter Help You Sleep?

Next Article

Do Blue Light Glasses Help with Night Driving?