What is blue light and why is it bad for your health?

What is blue light and why is it bad for your health?

If you think back to even just a few decades ago, no one was talking about “blue light.” While light rays emitted from the sun does show at different wavelengths or color temperatures, this wasn’t commonly seen as a health concern aside from uv rays and the need from sunscreen. 

During the day, people were exposed to brighter blue light, and at night, it turned into a darker, red light. However, in the modern day as people spend more and more time in front of flat-screen TVs, cell phones, e-readers, and even LED lights in general, we are starting to see some potentially negative effects of the artificial blue light typically emitted from these electronic devices. 

In this article, we’re going to break down exactly what blue light is, where it comes from, and the reasons that blue light exposure may be potentially harmful.

What is blue light?

To understand what blue light is, we have to first understand what wavelengths are. According to NASA, the visible light spectrum that we see is defined as “the segment of the electromagnetic spectrum that the human eye can view.” This spectrum is commonly known as high-energy visible light, or HEV for short. 

There are plenty of wavelengths, both short wavelengths and longer wavelengths, that are completely invisible to the human eye. In fact, the only wavelengths we can actually see are between around 380 nanometers to 700 nanometers. 

You may not notice these colors through daily life because you’re seeing the full visible light spectrum at once. However, if you’ve ever shined light through a prism, you’ll know exactly what this high-energy visible light looks like--a prism works to separate light into its different wavelengths, and each one will have a distinctive color. 

At the low end of the wavelength spectrum, i.e. short-wavelength, you’ll see dark blue, indigo, or violet. As you go higher toward the end of the spectrum, close to 700 nm, you’ll see light that is orange or even red. 

When you hear talk about “blue light,” this is light that falls usually between 380-500 nm. If you just walk outside during the day when the sun is out, you’ll be exposed to plenty of this type of light. Blue light makes up nearly a third of all the light you can see. So, you might ask, what’s the issue then? 

The sun does give off blue light during the day, but that has been the case for thousands of years. The new complication is the rise of digital devices and screen use at all hours of the day.

What does blue light do?

Blue light exposure is not unique to digital devices; we’ve been getting plenty of it from the sun for a long time. Given that, you might wonder why you would want to avoid it at all. The reason is not that is inherently bad, but rather that too much exposure or exposure at the wrong time can cause health problems with long-term effects. 

Light at that wavelength is meant to keep us energized. When our eyes see blue light, we feel invigorated, energized, and it even stops our brains from producing the sleeping chemical melatonin. 

On the other hand, when we see orange, reddish light, it does the opposite. It is a sign to our body that we should begin winding down to rest for the day. Even better, when we start to be in darkness, our brain finally starts trying to head off to sleep by then releasing that melatonin.

How does blue light affect me?

Under normal circumstances, being exposed to small amounts of blue wavelengths throughout the day is completely normal. It helps keep you going throughout the day, and can improve your alertness and even your energy. 

In addition, blue light is a part of light therapy, a treatment used to treat seasonal affective disorder. Many people, who may not get as much sunlight during the winter months, will deliberately spend time around blue light in order to boost their mood and energy levels.

The issue is not that any amount of blue light on its own is detrimental, but instead that it can lead to some other problems when you are exposed to too much of it at the wrong time.

What’s so bad about blue light exposure?

So, if blue light comes from the sun, and is even used to treat some forms of depression, what’s so bad about it? The two main issues that arise include eye strain, as well as potential disruption to your circadian rhythm.

Circadian Rhythms

Your body has what’s called a “circadian rhythm.” This is like an internal clock that helps regulate sleep patterns. A lot of this has been traditionally determined by the environment around you. 

When the sun is up, your body knows that it’s daytime. When the sun goes down, your body starts winding down, too. 

However, this isn’t the case anymore. 

As more and more people use digital screens at night that emit artificial light, sleep cycles can be disrupted because of the confusing signals being put out by blue light. If you’ve ever been up late at night in bed with your smartphone, you’ve probably experienced this. 

The later and longer you use a device that emits blue light, the more difficult it can be to fall asleep. This is not a coincidence. 

The light coming from your device is signaling your brain not to produce melatonin and to keep you awake. When it’s light from the sun, this is a helpful instinct, however it’s not so helpful late at night when you’re trying to sleep. 

In addition to changes to your sleep cycle, too high of an amount of blue light can also negatively affect eye health.

Eye Strain

One of the most common complaints we get is that eyes start to hurt or feel tired after long periods of time working in front of a computer screen or too much time in front of electronic devices. This is completely normal. Both the brightness of the screen and the shorter wavelengths can really take a toll on your eyes, especially when you’re doing it for eight or more hours every day.

Eye doctors at the American Optometric Association call this “computer vision syndrome,” also called “digital eye strain.”

Symptoms of digital eye strain include sore eyes, headaches, blurred vision, or even neck and shoulder pain due to the prolonged screen time.

With this in mind, too much blue light can seem to cause some significant problems. It’s important that your body is getting enough blue light during the day, but you don’t want to overexpose yourself after dark.

In a highly digital world, this can be difficult to balance. Many people get more blue light from screens than from the sun thanks to their jobs.

How to protect your eyes from blue light

There are a few different steps you can take to help relieve digital eye strain and protect your eye health from harmful blue light. 

Limit your exposure: spend less time on screens at night

The best thing you can do is to try to limit how much screen time you have late at night. If you are able to limit device usage after a certain time in the evening, this can dramatically reduce the effect that blue light has on your sleep schedule. 

Use light filtering software 

If simply cutting out screen time isn’t an option for you, you could look at using “night mode” features now commonly available in a lot of newer devices. Most smartphones and laptops now have a slider where you can change the wavelength of the screen’s light, commonly known as Night Mode or Night Shift; this may give your screen a strong orange tint, but it will help protect your eyes. These can be a great option, but keep in mind that they don’t always remove all of the blue light. 

Try blue light filtering eyewear

Another great way to deal with blue light is with blue light filtering glasses, sometimes known as "computer glasses." If you already wear glasses, adding a blue-light filter is a great way to combat possible negative effects.

Blue light blocking glasses are typically not very expensive, and it can save you a lot of headaches down the road. Even if you don’t already wear glasses, this is still an option for you.

At one time, the only blue light blocking eyewear you could buy had amber lenses and weren’t the most fashionable choice. However, now you can find stylish frames with clear lenses that are blue-light filtering without needing a prescription. 

Our Blue-Light Abbey, for example, is one of our most popular frames. Plenty of people wear them to help limit the harmful effects of blue light. If you’re someone who spends  40 hours a week in front of a computer screen, smartphone, or other digital devices, you should seriously consider grabbing a pair. 

If you get a pair from us at Look Optic, you even have 90 days to try them out risk-free. If you don’t like your new eyewear, feel free to send them back with free shipping - no problem. 

Our eyes are not very good at filtering blue light on their own, so having protective lenses can make an immense difference over time. 

We think that if you give these blue light glasses a shot, the results will speak for themself.


  1. https://science.nasa.gov/ems/09_visiblelight
  2. https://www.androidauthority.com/night-mode-on-android-886864/ 
  3. https://www.aoa.org/patients-and-public/caring-for-your-vision/protecting-your-vision/computer-vision-syndrome

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