The Dangers of Blue Light

We have all been exposed at one time or another to the concept of "blue light". Unfortunately, we have not yet taken the measure of the possible damage to our eyes and to our health in general. The harm caused by blue light is insidious and not always immediate. It goes far beyong simple eyestrain.

However, more and more scientific studies are highlighting the dangers of this phenomenon that 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 : filter and glasses

What is blue light?

Blue light is one of the colors naturally present in the spectrum of daylight. It is also emitted artificially by screens around us (phone, tablet, computer, television, some LED bulbs, etc.), so we are all exposed to it daily, whether at work or at home.

natural blue light

I. Blue light in the light spectrum

Sunlight contains red, orange, yellow, green and blue rays as well as many shades of each of these colors, also known as electromagnetic radiation. Combined, this spectrum of colored light rays creates what we call "white light" or sunlight. Blue light rays are therefore naturally contained in our environment, so it is not necessarily harmful when it comes from a natural source.

However, without exploring 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.

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

II. Natural blue light: essential to daily life

Turquoise-blue light is the natural light that stimulates wakefulness and calibrates our sleep rhythm. It is everywhere, but that is not necessarily a bad thing! This light is a necessity, especially at the beginning of 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.

It is directly linked to the production of melatonin.

This hormone that regulates your sleep. Natural blue light exposure in the morning lowers the level of melatonin in your body and allows you to wake up naturally. It also helps maintain energy balance throughout the day. In the evening, melatonin production increases and allows you to fall asleep peacefully.

danger artificial blue light

Research has also shown that this "good" blue light stimulates alertness, helps maintain a good memory, improves your cognitive functions and your mood. So it's not necessary (or desirable!) to block out 100% of the blue light!

"Screens emit blue light up to 100 times stronger and more aggressive than natural sources due to the powerful LEDs in your screens."

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

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

Difficult, however, when you know that this blue light is also ubiquitous. If we take the example of LEDs, they represented 75% of lighting in 2020! This is without counting their already systematic presence in your electronic devices.

Digital screens

Until the advent of artificial lighting, the sun was the main source of illumination 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 for our health that go far beyond eyestrain.

The "dark" side of light | Serious consequences

Every day, we are exposed to one or more screens for about 6 hours, and the increasing use of new technologies leads to an 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 blinking frequency of our eyes is decreased, thus reinforcing the phenomenon of digital eye strain / computer vision syndrome.

Disruption of sleep

Artificial blue light exposure disrupts your circadian rhythm. The light of our screens in particular delays our time of falling asleep and thus reduces our sleep time.

Blue light exposure makes your brain believe 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. Circadian rhythm is the backbone of a healthy life, its disruption can be truly dangerous.

II. Long term dangers

Vision loss | AMD (age related macular degeneration)

Prolonged exposure to blue light could also cause irreparable damage to the eyes and contribute to age-related macular degeneration, which can 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 and multilayered tissue covering the inner eyeball. It can be damaged by high energy blue rays (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 | ADHD

For younger children, studies have linked exposure to blue light from screens to attention deficit and hyperactivity disorder (ADHD) in young children. It goes without saying that 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...

Still much to discover

Worse still, research is beginning to highlight the (indirect) responsibility of blue light in certain cancers, diabetes, heart disease and even obesity (particularly because of its negative impact on sleep and circadian rhythm), and we are only at the beginning! Even if these are only preliminary studies, they already expose the devastating risks of blue light on our health and confirm once more that there is more to it than simple eye strain.

Discover today the most effective solutions to protect yourself from this invisible enemy: Horus X blue light glasses.

An easy way to protect yourself

To protect yourself from eyestrain and all the dangers of this nasty blue light, a simple blue light filter is not enough. Grab a pair of blue light glasses and protect your eyes.

Bibliography and further reading

  • Effets sur la santé humaine et l'environnement des systèmes utilisant les LEDsExpertise Anses 2019 
  • Ministère des Solidarités et de la Santé  
  • The Vision Council, "Digital Eye Fatigue in the USA : The State of the Art", Viewpoints, 2015, dans The Dangers of Blue Light, 2015
  • Rapport de la table ronde du 16 mars 2013, dans Les dangers de la lumière bleue, 2015
  •  "Sécurité photobiologique des lampes et des luminaires utilisant des lampes", EN 62471-1 ; "Application de la norme EN 62471 aux sources lumineuses et aux luminaires pour l'évaluation des risques de la lumière bleue", EN 62778
  •  Kasun Ratnayake et al, "Blue light excited retinal intercepts cellular signaling", Scientific Reports, 2018.
  •  L'accumulation de lipofuscine dans les cellules épithéliales pigmentaires rétiniennes cultivées entraîne une sensibilité accrue à l'irradiation par la lumière bleue", Free radic Biological Medecine, 1997.
  • Gianluca Tosini, Ian Ferguson et Kazuo Tsubota, "Effects of blue light on the circadian system and eye physiology", Molecular Vision, vol. 22, 24 janvier 2016
  • Sebastien Point, "Blue Light and Exposure Limit Value : Réponse à l'ANSES" [archive], 24 mai 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, janvier 2017
  •  Opinion on Potential risks to human health of Light Emitting Diodes (LEDs)" Comité scientifique de la santé, de l'environnement et des risques émergents SCHEER. 6 juin 2018
  •  La lumière bleue a un côté sombre". Harvard Health Letter. 13 août 2018
  •  Krigel, Arthur (2016). "Les dommages rétiniens induits par la lumière en utilisant différentes sources de lumière, protocoles et souches de rats révèlent la phototoxicité des LED". Centre de recherche des Cordeliers. Université Paris Descartes, France (Faculté de médecine de l'Université de la Sorbonne, département de physiologie). Consulté en décembre
  •  Les diodes électroluminescentes ont provoqué des lésions rétiniennes et leur dépendance à la longueur d'onde in vivo". International Journal of Ophthalmology, Vol. 10, No. 2. 18 février 2017. 9, 201