The real impact of blue light on eye health and sleep

Blue light blocking glasses are a widely used solution for blue light-related eye strain and sleep disruption, but do we really need them?
Maia Mulko
A pair of glasses held up to a screen.
Do blue light glasses really help?
  • Blue light from screens is often pointed to as bad for our sleep.
  • This has led to a growing market for blue light-blocking glasses.
  • But do these glasses really work? Let's find out.

Blue light is a type of visible light that is naturally emitted by the sun and artificially by LED-based screens, such as the ones on modern tablets, flat-screen TVs, smartphones, laptops, etc. 

According to a report by DataReportal, the average American spent just under 7 hours a day in front of screens in 2021, almost an hour more per day that in 2013. In the case of Gen Z, they spend up to 9 hours per day in front of screens.

This means that we are exposed to a lot of blue light, and this is believed to put us at a higher risk of vision problems and sleep disruption. 

The real impact of blue light on eye health and sleep
Gen Z can spend up to 9 hours per day in front of screens.

As our screen time has grown, so have blue light-related health concerns, as well as the popularity of blue light blocking glasses —which were first invented in the 1960s. 

Optometrists have been increasingly prescribing these glasses, since at least the 2000s, and the market for them is expanding at estimated annual growth rates of 8%. 

But do blue light blocking glasses really work? 

Blue light and its effects

Blue light is a type of visible light with a short wavelength, in comparison to other light on the visible spectrum. Blue light vibrated within the 380 to 500 nanometer range, giving it the shortest wavelength and highest energy. This means that it contains more energy per photon, providing more stimulation to the melanopsin retinal ganglion cells (mRGCs) on the eye’s retina.  

These photoreceptor cells detect light levels and transmit this information to the brain, helping activating or suppressing the production of melatonin, a hormone that promotes sleep, in response to changes in these light levels as the evening comes.  

The real impact of blue light on eye health and sleep
A lot of people have additional screen time on bedtime

This is why high levels of blue light are believed to interfere with our “internal clock” and affect our sleep patterns. Although blue light is a component of natural light from the Sun, if we’re exposed to blue light even after the sun has gone down (with artificial blue light from LED screens, for example), the production of melatonin is diminished and alertness is increased.

The short wavelength of blue light also means that it scatters more easily through the environment and in the eye, leading to glare which reduces contrast sensitivity, degrades image quality, and contributes to eye strain. 

The short wavelength of blue light is also thought to create oxidative stress in retinal cells when encountered at high intensities over time. This oxidative stress may contribute to retinal photochemical damage, potentially increasing the risk of eye conditions like age-related macular degeneration (AMD). 

Are blue light blocking glasses effective?

Blue light blocking glasses reduce the amount of blue light that enters the eyes, including from digital screens. These glasses use special lens coatings or materials designed to filter out or absorb a portion of the blue light, while allowing other wavelengths of light to pass through. 

Blue light blocking glasses are marketed as a solution to eye strain, sleep disruption, and potential retinal damage from blue light. They were in particularly high demand during the COVID-19 pandemic, when people relied more on their smartphones and computers for remote work, virtual education, and recreation. 

However, many scientists are not convinced of their effectiveness. 

The real impact of blue light on eye health and sleep
Some blue light glasses have yellow lenses to counterbalance the blue light

Recently, researchers from the Department of Optometry and Vision Sciences of The University of Melbourne and the School of Health Sciences of the City University of London concluded that there’s no proof that blue light blocking glasses make a difference when it comes to sleep quality and eye conditions.

This paper adds to studies that concluded that blue light blocking glasses did help improve sleep but they did not alleviate symptoms of eye strain, and studies that reported that evidence does not support the use of these glasses for the general population to aid with the aforementioned health issues. 

They argue that it’s not about the small percentage of blue light filtering (10%-25%). Higher percentages would be detrimental to color perception, anyway. 

It’s just that most scientists doubt that blue light by itself is actually responsible for eye conditions. The amount of blue light that our devices emit is not sufficient to harm our eyes, and eye strain can be explained simply by the high amount of screen time that we have every day. 

The American Academy of Opthalmology does recognize that blue light can affect sleep, though, especially in young people. For this reason, it recommends restricting blue light exposure at night by turning on night mode on our devices. 

In any case, there is more consensus around the fact that blue light impacts sleep than that it impacts sight. 

However, given that there is no strong evidence that blue light glasses improve sleep either, most experts do not recommend them. Instead, they recommend simply staying away from screens for one to three hours before bedtime, and using software-based blue light filters, such as iPhone and Android’s night mode or blue light blocking software.

Reducing negative effects of screens

So, if eye strain is not caused by blue light but rather by screen time, what can we do about it? At this point, reducing the amount of screen time is not always possible for many of us. 

Screen-induced eye strain, mostly known as digital eye strain, is a very common condition nowadays. In the U.S., almost 2 out of 3 people experience symptoms of digital eye strain —such as eye discomfort, eye fatigue, dry or irritated eyes, blurred vision, headaches, neck and shoulder pain, and light sensitivity after prolonged periods of screen time. It is also called Computer Vision Syndrome (CVS).

The real impact of blue light on eye health and sleep
Digital eye strain are caused by computers and smartphones alike.

To reduce these symptoms, experts often recommend following the 20-20-20 rule, which consists of taking a 20-second break to look at something 20 feet away for every 20 minutes of screen time.

Additionally, to minimize eye strain, you can:

  • Take a 10-20 minute break for every 1 or 2 hours that you spend in front of a screen.

  • Adjust screen brightness, contrast, and text size whenever you need it. Always try to equate your screen’s brightness to your surrounding’s lighting. 

  • Blink. It is a well-known fact that our blink rates decrease when we’re using digital devices. If we “forget” to blink, we can develop dry eye more easily.

  • Visit your opthamologist for regular eye exams.

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