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How Blue Light Affects Your Eyes

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Do you sometimes find it hard to sleep at night? Chances are that blue light is affecting your body's biological clock and disrupting your sleep patterns. This is a reality for many people if you consider that an average modern human being spends almost 5,000 hours staring at screens that emit blue light.

It’s inevitable that as digital technologies continue to be available to more people, exposure to blue light will also increase. But what is blue light? Where can you find blue light? Is blue light good or bad for your eyes? If blue light has adverse effects on your eyes, what can you do to protect your eyes from these effects?

In this comprehensive article, we answer all the above questions. We look at how blue light affects your sleep patterns. More importantly, we provide some advice on what you can do to protect your eyes from the negative effect of blue light, particularly artificial blue light.

What is Blue Light?

When many people think about blue light, they think about the light that comes from the screens we interact with every day: television, smartphones, laptops, computers, and tablets. However, the reality is that blue light has always been around as part of natural light.

To understand what blue light is, we need to understand what light is made of. Light is a result of electromagnetic particles which emit energy as they travel in waves of different length. If you look at a rainbow, you will see that visible light is a combination of several colors, of which one is blue light.

The naked human eye can see only a small portion of the electromagnetic spectrum of light. This small portion has a wavelength range between 400nm and 750nm. The nanometer (nm) is the unit of measure for the electromagnetic spectrum wavelength. 

Blue light constitutes the visible spectrum's first part, which has a short wavelength of about 400nm. Having a shorter wavelength means that blue light has higher energy. 

Blue light is referred to as such because it is perceived as the color blue. While this may be true, it is also true that blue light may be present when the light is perceived as white or any other color. Thus, any device that produces light is also likely to be producing blue light too.  

Is Blue Light the Same as UV Light?

Blue light is not the same as Ultraviolet (UV) light. They both result from the sun, but they affect the human eye and body differently. UV light is a non-visible light with wavelengths between 100nm and 400nm. Having a shorter wavelength than blue light, UV light has more energy and causes more harm, including burning the skin.

Blue light, however, can penetrate through the anterior structures of the human eye. This means that blue light can quickly get through to the retina, unlike UV Light, and cause photochemical damage (damage to the retina attributed to light). The retina is a thin layer of tissue lining the back of the eye on the inside. 

While ordinary sunglasses can protect you against UV light, they do not have the same effect when it comes to blue light. However, it is the best option to keep your eyes healthy in the presence of direct sun. Your sunglasses act as a shield against UV rays only. 

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Where can you Find Blue Light?

Since we have already indicated that blue light emanates from the sun, it is everywhere. Other sources include artificial sources, such as LED lighting, fluorescent, electronic devices, and digital screens. This means that getting rid of screens will not, on its own, eliminate blue light.

Stepping outdoors during the day is where we get most of our exposure to blue light. Is the sun’s blue light harmful? The answer is no. It is highly beneficial for our mental and physical health, preventing us from suffering from Seasonal Affective Disorder (SAD). This depressive disorder is linked to a decrease in natural sunlight.

Blue light from the sun also plays a vital role in maintaining our circadian rhythms (the internal process regulating the sleep-wake cycle), giving us a boost of energy, and making us feel more alert. In other words, natural high-energy visible light (HEV) blue light is a health boost. 

Although the blue light wavelengths' exposure we receive from screens is small, they tend to have long-term effects due to the screens' proximity and the length of time you are using the device. Thus, a report from Harvard Health Publishing called light from screens the dark side of blue light.

There are several sources of artificial blue light: 
• Smartphones
• Tablets
• Personal computers and laptops
• TV
• Gaming consoles
• VR helmet
• LED light bulbs
• Energy-efficient fluorescent bulbs
• Digital clocks

women suffer from digital eyestrain

What are the Effects of Blue Light on Your Eyes?

As the world becomes more digital, more people are devoting more time to enjoy their electronic devices in proximity. This usage rate has been a concern to eye doctors and health care professionals about the long-term effects. 

Eye Strain

A Unilever report revealed that 64% of people are unaware of how blue light negatively affects the skin because of its ability to penetrate the skin deep down into the subcutis layer (the skin’s innermost layer).

It is worthy of note that blue light from digital devices and screens can decrease contrast, resulting in a situation known as digital eye strain.  Over time, this could result in damage to the retinal cells.

According to a report published by ANSES (French Agency for Food, Environmental and Occupational Health & Safety), experts carried out assessments of the effect of LEDs and blue light on human health. Short-term effects on the retina were linked to intense exposure to blue LED light, while long-term effects were linked to age-related macular degeneration.

Because blue light has very short wavelengths, it can cause a flickering sensation. The flicker is often linked to a glare effect that affects the visual contrast. This could make your eyes struggle to see clearly. As a result, images can lose their sharpness and clarity, which the eye needs to compensate for. 

Interfering With Everyday Life

Blue light can make it hard in everyday life. It increases eye strain, headaches, difficulties concentrating, and physical fatigue. In the long term, prolonged exposure to artificial blue light can also lead to retinal damage and facilitate age-related macular degeneration (AMD).

Macular degeneration is caused by the destruction of cells in the center of your eye retina. Your retina has natural screen protection, called melanin, against harmful blue light rays. However, the melanin, which is the same component you find in the skin, degrade as part of the aging process. As this happens, we naturally lose our protection.

Considering that melanin regulates the sleep-wake cycle, it can be argued that exposure to blue light may interfere with your ability to rest at night. If you are unable to rest sufficiently, your ability to function is impacted. This interferes with your everyday life. 

Adults in both the US and the UK spend an average of almost five hours a day doing online activities. In that case, it becomes essential to take the effects of blue light from screens more seriously. However, very few take preventive measures to reduce their discomfort, which puts their eye health at risk in the long term.
 

How Does the Effect of Blue Light on Eyes Affect Sleep?

Circadian rhythms are responsible for the timing of many processes, including sleeping and feeding. However, the introduction of artificial blue light into our lives is disrupting our body’s biological clock. Because the body is exposed to blue light long after the sun goes down, the brain can't manage sleep hormone production.

An experiment by researchers from Harvard concluded that exposure to blue light subdued melatonin production. Melatonin is the hormone regulating the sleep-wake cycle. If this hormone is not produced, individuals start to experience sleep challenges because the body fails to regulate the sleep-wake cycle. 

Writing for the medical website, Brighamhealthhub.org, Steven Lockley, Ph.D., and Shadab Rahman, Ph.D. report that exposure to blue light at night leads to people failing to get enough sleep needed for their wellbeing. Thus, researchers have associated compromised rest in the night with amplified risk for depression and other cardiovascular problems.

In a study published by the Proceedings of the National Academy of the United States of America, Anne-Marie Chang, Daniel Aeschbach, Jeanne F. Duffy, and Charles A. Czeisler show the effects of blue light on sleep. They report that “participants reading a LE-eBook took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock, and reduced next-morning alertness than when reading a printed book.” 

The studies above demonstrate a negative link between exposure to high amounts of blue light for sleep, health, safety, and performance.

While some studies correlated exposure to blue light at night to obesity, diabetes, and heart disease, there is, however, not enough proof that blue light exposure in the night causes these conditions. It could be argued though that these conditions have often been linked to sleep disorders. 

Protecting Your Eyes from Negative Effects of Blue Light?  

Natural blue light is not always bad. It can regulate our wake-sleep cycle and the biological clock. This type of light also plays a role in other basic brain functions, like cognitive performance, alertness, and the ability to remember.

However, if your eyes are exposed to high artificial blue light levels, you may need to consider ways to protect your eyes.

A natural way to guard your eyes against eye damage caused by blue light in devices is always to take regular breaks using the “20-20-20” rule. This rule suggests that every 20 minutes, you should make an effort to move your eyes away from your screen, and look at another object at least 20 feet away for a minimum of 20 seconds.

Taking breaks is not always possible in a busy workplace. In such cases, you can take eye health supplements that help protect the macular pigment at the center of your eye. Supplementing your diet with carotenoids: lutein, meso-zeaxanthin, and zeaxanthin, which are the three carotenoids (chemicals preventing the eye from light induced damage) in the macula, is advisable.

If you work on computers and laptops and are looking for a long-term solution, consider blue light glasses. These can be an effective way of protecting you from harmful HEV rays, no matter how busy you are.

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