The Blue Light, its Benefits and Dangers

The Blue Light

The visible light is a form of electromagnetic energy that forms part of what is scientifically known as the 'Electromagnetic spectrum.'

The electromagnetic spectrum is made of electromagnetic particles that travel in waves.

These waves emit energy and have different lengths and strengths. The shorter the wavelength, the higher the energy of these particles.

These particles' wavelength is measured in nanometers (nm), with 1 nanometer equaling one billionth of a meter.

 Each wavelength has its own color/name. They are grouped into gamma rays, x-rays, ultraviolet (UV) rays, visible light, infrared light, and radio waves.

 Electromagnetic Spectrum

Some of the radiations of the Electromagnetic spectrum are not visible and may be harmful to the human eye, such as the Ultra-Violet (UV) light.

On the other hand, visible light is essential for human vision. A human eye observes the visible light as colors: violet, indigo, blue, green, yellow, orange and red.

Blue light is a high-energy light with a short wavelength, while red light has less energy and a longer wavelength. Due to this higher than average energy, overexposure to the blue light is harmful to the human eyes.

Sources of Blue Light

The Sun

Fan fact, why is the sky blue? 

The air and other particles scatter light in all directions.

However, since blue light has a shorter wavelength than other colors, it is scattered more. That is why the sky is mostly blue. The sun is, therefore, the largest source of blue light.

The sun as a source of blue light

The sunlight has 100 times more intensity of harmful blue light than light emitted from digital screens.

Squinting is our body’s natural defense against harsh light and bright glare.

Artificial Lighting

LED lights and Fluorescent used in offices, and our home emits high amounts of high energy light, including blue light. Some of these screens include screen monitors, smartphone and tablet screens, TV sets, and gaming systems.

Source of Blue Light; Artificial Lighting

Digital Screens

Digital screens use LED lighting. LEDs emit a lot of high energy light that is harmful to a person's eyes if exposed for a long time. 

Source of Blue Light-Digital screens

Importance of Natural Blue Light

Blue light from the sun is helpful to the body. The light boosts attention levels during the day, making you more attentive and productive.

It also helps cognitive and memory functions.

Blue light is also known to elevate the mood of a person. Lack of exposure to the sun for a prolonged period might result in issues such as:

  • Feeling depressed most of the day, nearly every day
  • Losing interest in activities you once enjoyed
  • Experiencing changes in appetite or weight
  • Having problems with sleep
  • Social withdrawal (feeling like "hibernating")

Light influence the Circadian rhythms in the human body. Circadian rhythms are the internal process that regulates the sleep-wake cycle every 24 hours. It is very sensitive to blue light.

 When the cycle is aligned, a Circadian rhythm can enhance consistent and restorative sleep, but if it is disrupted, this can result in sleeping problems such as insomnia.

 Dangers of Blue light

According to a Harvard Medical school study, exposure to artificial light at night leads to several health issues such as diabetes, heart disease and obesity.

Blue light suppresses the secretion of melatonin, a hormone that controls the circadian rhythms. As a result, exposure to blue light at night interferes with circadian rhythms.

 It makes people not have enough sleep. Lack of enough sleep is linked to cardiovascular problems, depression and diabetes.

Other studies have found out that blue light flickers more quickly due to its short wavelength compared to different colors with a longer wavelength.

The flickering creates a glare that reduces the visual contrast, sharpness and clarity of vision.

Computer glare

As a result of the flickering glare, a person might experience eyestrain, headaches, physical and mental fatigue due to long hours of exposure to the blue light, a condition known as Digital Eye Strain Syndrome.

Blue light may also cause long-term damage to the eyes, such as retina damage, accelerate age-related macular degeneration and even vision loss.

Another Harvard study states that "High Energy Visible (HEV) blue light has been identified for years as the most dangerous light for the retina.

After chronic exposure, one can expect to see an increase in macular degenerations, glaucoma, and retinal degenerative diseases".

American Macular Degeneration Foundation (AMDF) claim that "the blue rays of the spectrum seem to accelerate age-related macular degeneration (AMD) more than any other rays in the spectrum".

Blue light from sunlight can cause eye strain and fatigue.

Ways of Protecting Your Eyes from Blue Light

Wearing Protective Eyewear

Protective ophthalmic lenses with a special coating designed to reflect and cut high energy blue light penetration. This coating is commonly referred to as Blue light blocking coating.

Blue Light Blockers

Wearing Glasses with Blue-Light Blocking Coating reduces the flickering of high energy light, increasing the contrast of the screen, less eye strain and fatigue.

The University of Montreal study found that wearing blue light blocking glasses reduced eyestrain symptoms by half.

In another research, scientists at the University of Toronto compared the melatonin levels of people exposed to bright indoor light wearing blue–light–blocking glasses to another group exposed to typical dim light without wearing glasses.

The stories of the melatonin hormone were similar in the two groups. It proved that blue light is a suppressor of melatonin.

Such glasses would be ideal for people who work overnight or people who work late into the night.

Blue Light blocking Lenses

Reduce Glare

To overcome eyestrain from working behind a screen, you can reduce the brightness of your screen. Another way of doing it is by changing the background color from bright white to grey.Computer glare


At night, one can also dim any LED indoor lighting. 

Observe the 20-20-20 Rule

One of the most efficient ways of reducing eyestrain is observing a rule called the 20-20-20 rule.

This rule states that after every 20 minutes of staring at a screen, one should take a 20 seconds break and look at a 20 feet away object.


The 20-20-20 rule

Reduce screen time

Reducing the amount of time spent looking at the digital screen can be another method to limit eye strain, especially at night.

Looking at a screen for more than 2 hours continuously is not healthy for your eyes.




Harvard Health Publishing