We've all been exposed to the concept of blue light at one time or another. It is even guaranteed that you are reading this article on a device that emits a good amount of it! It is a relatively simple term that hides a complex reality. It is difficult to measure the possible damage on our eyes and on our health in general because themisdeeds of blue light are sneaky and are not always immediate.

However, more and more scientific studies are highlighting the dangers of this phenomenon, which is still not discussed enough.

In this guide :

  • What is blue light
  • Natural blue light
  • Artificial blue light
  • The dangers of blue light
  • Effective protection

What is blue light?


There is no way to escape it, we are exposed to it every day, whether at work or at home.

Where is the blue light found?

  • 🌅 Blue light is one of the colors naturally present in the spectrum of daylight emitted by the sun.
  • 💡 It is also present in modern LED lighting, which often emits a cold white light.
Graph representing the sources of blue light (sun, screen, led lighting)


Our relationship with screens is incredible: 

⌚ We will spend more than 27 years of our lives online on average ( North study)

⏰ Time spent on the Internet by children aged 1 to 6 has almost tripled in 10 years ( Ipsos study)

I. Blue light in the light spectrum

A light among many others

Sunlight contains red, orange, yellow, green and blue rays as well as many shades of each of these colors, also known as electromagnetic radiation.


Graphic representing the natural blue light with the sun in the middle of a landscape

☀️ Combined, this spectrum of colored light rays creates what we call "white light" or sunlight.

Blue light is therefore naturally contained in our environment, so it is not necessarily harmful. It should also be noted that it is dynamic: the light intensity and color temperature vary throughout the day. This is often a fundamental difference compared to working on a screen.

The physical characteristics of blue light

Without exploring the complex physics, there is an inverse relationship between the wavelength of light rays and the amount of energy they contain.

👉 Long-wavelength light rays contain less energy, and short-wavelength rays contain more energy.

🔴 Rays at the red end of the visible light spectrum have longer wavelengths and therefore less energy.

🔵 On the other side of the spectrum, blue light has shorter wavelengths and therefore contains more energy.

The blue light: double face!

This blue light can itself be divided into 2 categories. One essential for our health and the other much less.


Decomposition of the blue light spectrum

And even on this last distinction, the border is sometimes blurred because the harmfulness also depends on the time of exposure and the intensity of this light (during the day the harmful spectrum is limited to the frequencies close to UV, in the evening, all blue light can impact your health). 

II. Natural blue light: essential for everyday life

Blue daylight is the natural light that stimulates wakefulness and calibrates our sleep rhythm.

Graphic description of the day-night sleep cycle

You only have to look at the sky on a clear day to see it: The entire light spectrum passes through our atmosphere, but the sky generally looks blue because the blue light waves bounce off and scatter on the nitrogen and oxygen particles in our atmosphere.

In short, blue light is ubiquitous, but this is not necessarily a bad thing! On the contrary! 

👨🏫 This light is a necessity, especially early in the day. As early as 1981, Dr. Charles Czeisler of Harvard Medical School highlighted the importance of daylight in synchronizing the internal clock with the environment.

⚠️ Blue light impacts melatonin production!

Melatonin is the hormone that regulates your sleep. It helps to maintain an energy balance throughout the day but especially : 

📉 Natural blue light in the morning lowers the level of melatonin in your body and allows you to wake up naturally.
📈 At night, melatonin production increases and allows you to fall asleep peacefully.
There are alternatives to melatonin but the best thing is to respect your body so that it is not completely upset. 
graphic design of blue light led bulbs on black background


Research has also shown that this "good" blue light stimulates alertness, helps maintain a good memory, improves your cognitive functions and your mood.

It is therefore not necessary (nor desirable!) to block 100% of blue light all the time!

III. Artificial blue light: harmful in the short and long term

The most harmful blue-violet light is that between 380 and 450 nanometers, because its very short waves are the most energetic and therefore the most harmful to the eye. These are the ones to be avoided in priority. 

In addition, the entire spectrum of light affects your sleep. It is therefore necessary when you want to fall asleep normally, to avoid the entire spectrum of blue light from 380 to 500 nanometers. 

Blue light therefore presents risks:

  • In the evening: on the whole spectrum (380 to 500 nanometers)
  • The day: on the part closest to the UV from 380 to 450 nanometers.

graph showing the harmfulness of blue light during the day and at night

Difficult, however, when you know that this blue light is omnipresent, day and night.

🤯 If we take the example of LEDs, they would represent 75% of lighting in 2020! That's without counting their already systematic presence in your electronic devices.

representation of a screen that emits blue light

Until the advent of artificial lighting, the sun was the main source of light and people spent their evenings in (relative) darkness.

Today, in much of the world, evenings are artificially lit, and this constant exposure can have serious consequences on our health.

The "dark" side of blue light | Why blue light is harmful

Every day we are exposed for about 6 hours to one or more screens, and the increasing use of new technologies leads to overexposure of the eye to harmful blue light.

I. Short-term hazards

Visual fatigue

Stinging sensations, red, dry and tired eyes, jumping eyes, glare, blurred vision, headaches... At the same time, the frequency of blinking is reduced, thus reinforcing the phenomenon.

Sleep Disruption

Artificial blue light disturbs your circadian rhythm. The light from our screens in particular delays our time of sleep and thus reduces our sleep time.

Blue light makes your brain think that you are in the middle of the day. It prevents the secretion of melatonin, the hormone that allows us to fall asleep. The sleep is then disturbed, our body does not know any more at which moment it must fall asleep.

Here is an excerpt from the opinion of the ANSES (National Agency for Food, Environmental and Occupational Health Safety)

Acute exposure to intense blue light can lead over time to a permanent decline in visual acuity, partial or total. The expertise of the Anses conducted in 2010 highlighted the toxicity of blue light for the retina. The new scientific data confirm this result and identify short-term phototoxic effects related to acute exposure to light rich in blue, and long-term effects related to chronic exposure over several years, which may increase the risk of age-related macular degeneration (AMD). Some experimental studies on animals also show that the retina is more vulnerable to the effects of phototoxicity during the night.

II. Long-term hazards

Loss of vision | AMD

Prolonged exposure to blue light could also cause irreparable damage to the eyes and contribute to age-related macular degeneration, which can itself lead to blindness. Although there is still a lot of research to be done before definitive conclusions can be reached, the initial results are disturbing.

The retina is a very thin, multilayered tissue covering the inner eyeball. It can be damaged by high energy blue light (especially in children). Prolonged exposure can therefore be a risk factor for age-related macular degeneration.

A Harvard medical study indicates that high-intensity radiation is the most dangerous light for the retina and retinal degenerative diseases. A report published by the American Macular Degeneration Foundation (AMDF) reports that "blue spectrum light appears to accelerate age-related macular degeneration (AMD) more than any other ray in the spectrum."

Attention Deficit Disorder | ADHD

Concerning the youngest, studies have established a link between exposure to blue artificial light emitted by screens and attention deficit and hyperactivity disorders (ADHD) in young children. It goes without saying that the youngest children must be protected as much as possible from overexposure to screens. Avoid as much as possible tablets or smartphones to keep baby busy...

Acceleration of puberty 

A recent study presented at the 60th Annual Meeting of the European Society of Pediatric Endocrinology in Rome suggests that screen time during periods of confinement may be to blame.

Researchers from Gazi University and Ankara Hospital in Turkey exposed 18 immature female rats to a spectrum of light primarily emitted by LED screens for relatively short or long periods each day. They found that those exposed to blue light for long periods showed signs of maturity earlier than the others.

This does not mean that other factors may not play an important role. The biology of puberty is incredibly complex, but these initial findings provide a good foundation for this theory. 

Who are the most sensitive to blue light?

  • The children
  • People who already have eye problems
  • Immunocompromised persons
  • The seniors 

How to protect yourself from blue light?

Protecting yourself from blue light is essential to preserve your retina, your sleep and your health in the long term. 

  1. Reduce screen time
  2. Avoid exposure to blue light before bedtime 
  3. Absolutely avoid blue lights and any strong light at night
  4. Activate blue light filters and other night modes on your electronic devices. 
  5. Equip yourself with effective anti blue light glasses

All of these solutions are excellent, but the most effective is the blue light glasses specially designed to filter the bad light of the spectrum. 

Which anti blue light glasses to choose?

It is essential to choose an anti blue light glasses with an advanced filtration technology. The criteria to check are simple to know how to choose your anti blue light glasses but not so easy to find: 

  • 100% filtration of ultraviolet rays (A, B and C)
  • Near 100% filtration in the ultra-harmful spectrum between 380 and 430 nanometers
  • Powerful anti-reflection (find out why an anti-reflection here)
  • Ergonomic design adjusts to your body shape
  • Certification by an independent laboratory
  • An advanced guarantee 

The selection of the best anti blue light glasses according to your use

For your parties

The gaming One or the Urban round gaming glasses with amber filter 

For Gaming

The Revolution. equipped with an amber filter

For the office or on the road

The nomadic collection of anti blue light glasses equipped with a clear filter 

For children

The Hope if they are gamers or the collection anti blue light glasses child pass everywhere.

Blue light true or false? Still a lot to discover

Worse still, research is beginning to show that blue light is responsible for certain cancers, diabetes, heart disease and even obesity (particularly because of its negative impact on sleep), and we're just getting started! Even if these are only preliminary studies, they already expose the devastating risks of blue light on our health.  

Discover today the most effective solutions to protect you from this invisible enemy: Horus X Visual Shield

Bibliography and further reading

  • Effects on human health and the environment of systems using LEDsAnses review 2019 https://www.anses.fr/fr/system/files/PRES2019DPA01.pdf 
  • Ministry of Solidarity and Health https://solidarites-sante.gouv.fr/sante-et-environnement/activites-humaines/exposition-aux-ondes/article/effets-sur-la-sante-de-l-exposition-a-la-lumiere-bleue  
  • The Vision Council, "Digital Eye Fatigue in the USA: The State of the Art," Viewpoints, 2015, in The Dangers of Blue Light, 2015
  • Report of the March 16, 2013 roundtable, in The Dangers of Blue Light, 2015
  •  "Photobiological safety of lamps and luminaires using lamps", EN 62471-1; "Application of EN 62471 to light sources and luminaires for blue light risk assessment", EN 62778
  •  Kasun Ratnayake et al, "Blue light excited retinal intercepts cellular signaling," Scientific Reports, 2018.
  •  Lipofuscin accumulation in cultured retinal pigment epithelial cells leads to increased sensitivity to blue light irradiation", Free Radical Biological Medicine, 1997.
  • Gianluca Tosini, Ian Ferguson, and Kazuo Tsubota, "Effects of blue light on the circadian system and eye physiology," Molecular Vision, vol. 22, January 24, 2016
  • Sebastien Point, "Blue Light and Exposure Limit Value: Response to ANSES" [Archive], May 24, 2019.
  •  Huei-Bin Wang et al, "Blue light therapy improves circadian dysfunction as well as motor symptoms in two mouse models of Huntington's disease," Neurobiology of Sleep and Circadian Rhythms, vol. 2, January 2017
  •  Opinion on Potential risks to human health of Light Emitting Diodes (LEDs)" Scientific Committee on Health, Environment and Emerging Risks SCHEER. June 6, 2018
  •  Blue light has a dark side". Harvard Health Letter. August 13, 2018
  •  Krigel, Arthur (2016). "Light-induced retinal damage using different light sources, protocols, and rat strains reveals LED phototoxicity." Cordeliers Research Center. Université Paris Descartes, France (Sorbonne University Faculty of Medicine, Department of Physiology). Accessed in December
  •  Light-emitting diodes induced retinal damage and wavelength dependence in vivo." International Journal of Ophthalmology, Vol. 10, No. 2. 18 February 2017. 9, 201