Does Blue Light Mess With Your Brain? (Optical Physics)
And How Do Blue Light Glasses Even Work?
In 2024, it’s fairly common to hear terms like “blue light blockers”, “blue light filters” or “blue light glasses”. These terms can be confusing to some. I hope to explain the meaning and science behind these terms and how they impact your life as a human being.
The most common conception that has been circulating the internet about blue light is that the blue light emitted from the screens on your phones, laptops, tablets, monitors, and televisions can affect your brain and disrupt your circadian rhythm (AKA the timing and quality of your sleep).
While it makes sense that bright light can strain your eyes, what makes blue light special? And can it really disrupt your sleep? I hope to answer these questions in this article.
What Is Blue Light And What’s So Special About It?
While It may seem that blue light is a code word for a very complex and specific form of light, that’s not the case. In essence, blue light just refers to emitted light that appears to be the colour blue. This can be a blue LED, a blue image on your phone, or even the sky on a clear day.
Blue light is specifically viewed as bad for your brain, but why is that? Well, that’s because the colour blue has the highest energy of all the colours. There’s a lot of physics behind it, and if you’re not interested, feel free to scroll down a little.
So, every ray of light you observe has a different wavelength and frequency. In fact, the visible light spectrum is only a small portion of the electromagnetic spectrum, which contains a huge variety of wavelengths.
As you can see from this image, the light we can see is a very small part of the overall electromagnetic spectrum. You can also see that as the image goes along, the wavelength decreases (the waves get shorter). While this may seem insignificant, it’s actually quite important.
Due to the Universal Wave Equation for light:
c = f x λ
where c represents the speed of light, f represents the frequency, and λ represents the wavelength, we can determine that, as the wavelength gets shorter, the frequency must increase (because the speed of light is constant).
Also, one of Einstein’s equations helps us determine that shorter wavelengths = more energy:
E = (hc) / λ
In this formula, where h represents Planck’s constant, we can see that λ is in the denominator. Therefore, as wavelength decreases, energy increases.
If we refer back to the electromagnetic spectrum, then we can see that blue light has a very short wavelength, therefore it has the highest frequency and the highest energy.
That’s why it’s thought that the brain is stimulated and strained by blue light. If it has the highest energy of any colour, it must also take a lot of energy to look at, right?
Is It Really Harmful?
This is where it gets complicated. Blue light isn’t truly harmful to humans. It’s as harmful as any other colour. However, due to the high energy of the blue light rays, the colour signals our brain to be alert. It boosts focus and attention, and it suppresses an essential chemical in us called melatonin.
Melatonin is the chemical in your brain that signals the brain to get ready to sleep and recover. It has the duty of calming you down and reducing stress. Since blue light has the power to suppress it, your sleep can be negatively impacted, similar to the effects of caffeine.
This wasn’t a relevant issue in the history of humans; however, with the revolution of digital computer technology, we’re constantly looking at our screens. And our screens emit blue light rays. This is problematic because, naturally and biologically, our brains expect bright blue light in the day and calming warm colours, like that of a sunset, at night-time.
You may notice that when it’s a dark gloomy day, you may find it harder to get excited about things or be active. This is because of the lack of sunlight and blue light in the sky.
But imagine if you were always exposed to the blue light that boosts activeness and focus. You wouldn’t ever feel truly sleepy and the quality of your sleep would be hindered. A common effect of blue light is that it takes longer to fall asleep. This means that exposure to blue light at the wrong times can also completely disrupt your circadian rhythm.
Due to this new prominent issue, it has become a subject of importance to tech companies and health professionals. In 2024, most smartphones are being released with features like blue light filters, blue light blockers, or even eye comfort mode. These work by changing the overall colour of the screen to a more calming, warm, orangeish colour. This can reduce the amount of blue light rays being emitted from your phone.
Another attempt at reducing the effects of this blue light is the invention of blue light glasses.
Do Blue Light Glasses Work?
I own a pair of blue light glasses, and I can definitely notice that there is less strain on my eyes without changing my vision in any noticeable way. But do they truly circumvent the effects of blue light at night? To answer this question, it’s important to know how they work.
Well, some of them work the same way that the phones do. They have a warm-coloured filter on the glasses to allow your eyes to only collect red, orange, or yellow light. Like this one.
Others don’t appear orange at all. Instead, they work by allowing more warm colours to pass through the glasses and completely reflecting (or absorbing) green and blue light rays. They accomplish this by allowing only certain rays with specific wavelengths to pass through. Like this one.
The physics behind this is very complex, so I won’t get into it in this article, but if you wish for an article about that, please let me know in the comments!
It turns out that both of these glasses are indeed effective, since they filter out the blue light wavicles. The pair of glasses you use depends on the use case. The tinted and filtered glasses are particularly useful at night. This is because they block a higher percentage of blue light and contain calming warm colours. And at night time, humans aren’t supposed to view blue and green colours.
The ones that reflect or absorb blue light are very effective too, but they contain a clear lens and therefore still allow some blue light to enter your eyes. They are more effective during the day to prevent long-term effects on your brain and hormones. The benefit to these is that they barely change your vision, if at all.
Please note that the links I inserted above are affiliate links. If you choose to purchase either of these glasses, I would heavily appreciate it if you used my link. It allows me to keep writing about tech and physics. Thank you.
Conclusion
So, blue light isn’t actually bad for you, but the waves have a lot of energy, With the rise of digital technology and artificial lights, we are exposed to bright blue light far more than we should be. Also, humans shouldn’t be exposed to blue light rays after sunset anyway. This causes us to have poor sleep and an out-of-whack circadian rhythm.
That is why you should really stay off of screens close to bed time. However, that’s not suitable for a lot of people. If you must use technology, I would definitely recommend that you invest in some protection and turn on the display settings on your phone. Personally, I have my phone switch to eye-comfort mode at 8:00 PM every day and in the morning, it switches back.
Thanks for reading!
