We have all been exposed at one time or another to the concept of blue light. 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 nevertheless hides a complex reality. It is difficult to take the measure of the possible damage to our eyes and to our health in general because the harmful effects of blue light are sneaky and are not always immediate .

However, more and more scientific studies are highlighting the dangers of this phenomenon that is still too little discussed.

In this guide:

  • What is blue light
  • natural blue light
  • artificial blue light
  • The dangers of blue light
  • Effective protection

What is blue light?

Impossible to escape it, we are exposed to it daily, whether at work or at home.

Where do we find blue light?

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

Our relationship to screens is incredible:

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

⏰ The 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 called electromagnetic radiation.

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

☀️ Combined, this spectrum of colored rays of light 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 the color temperature vary throughout the day. This is an often fundamental difference compared to working on screen.

The physical peculiarity of blue light

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 light 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.

Blue light: double face!

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

Blue Light Spectrum Decomposition

And even on this last distinction, the boundary 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 frequencies close to UV, in the evening, the whole 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 pattern .

Graphic description of the day-night cycle on sleep

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

In short, blue light is everywhere, but that's not necessarily a bad thing! On the contrary !

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

⚠️ Blue light impactsmelatonin production !

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

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

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

It is therefore not necessary (or 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 that should be avoided first.

Add to that that the whole spectrum of light impacts your sleep. It is therefore necessary when one wishes to fall asleep normally, to avoid the whole spectrum of blue light from 380 to 500 nanometers.

Blue light therefore presents risks:

  • In the evening: over the entire spectrum (380 to 500 nanometers)
  • During the day: on the part closest to 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 accounted for 75% of lighting in 2020! This is without taking into account 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 some (relative) darkness.

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

The “dark” side of blue light | Why blue light is harmful

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

I. Short-term dangers

visual fatigue

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

Sleep disturbance

Artificial blue light disrupts your circadian rhythm. The light from our screens in particular delays the time we fall asleep and thus reduces our sleep time.

Blue light tricks your brain into thinking it's daylight . It prevents the secretion of melatonin, the hormone that allows us to fall asleep. Sleep is then disturbed, our body no longer knows when to fall asleep.

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

Acute exposure to intense blue light can lead to permanent, partial or total loss of visual acuity over time. The ANSES expert appraisal carried out in 2010 highlighted the toxicity of blue light for the retina. The new scientific data support this result and identify short-term phototoxic effects related to acute exposure to blue-rich light, and long-term effects related to chronic exposure over several years, which may increase the risks. onset of age-related macular degeneration (AMD). Certain experimental studies on animals also show that the retina is more vulnerable to the effects of phototoxicity during the night.

II. Long term dangers

Loss of vision | AMD

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

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

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

Attention Deficit | ADHD

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

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 lockdowns 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 from LED screens for relatively short or long periods each day. They found that those exposed to blue light for long periods of time showed signs of maturity earlier than others.

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

Who are the most sensitive to blue light?

  • children
  • People who already have eye problems
  • Immunocompromised people
  • Seniors

How to protect yourself from blue light?

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

  1. Reduce time spent on screens
  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. Wear effective blue light blocking glasses

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

Which blue light blocking glasses to choose?

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

  • 100% filtration of ultraviolet rays (A, B and C)
  • Filtration close to 100% on the ultra harmful spectrum between 380 and 430 nanometers
  • Powerful anti-reflection (find out why an anti-reflection here )
  • An ergonomic design adjusts to your morphology
  • Certification by an independent laboratory
  • A comprehensive guarantee

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

For your evenings

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

For Gaming

The Revolution . equipped with an amber filter

For the office or on the go

The nomad collection anti-blue light glasses equipped with a clear filter

For kids

The Hope if they are gamers or the children's blue light blocking glasses collection goes everywhere.

Blue light true or false? Still a lot to discover

Worse still, research is beginning to point to blue light being responsible for certain cancers, diabetes, heart disease, and even obesity (particularly because of its negative impact on sleep), and we're not sure. only at the beginning! 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 yourself from this invisible enemy: Horus X Visual Shield .

Bibliography and further reading

  • Effects on human health and the environment of systems using LEDsExpertise Anses 2019 https://www.anses.fr/fr/system/files/PRES2019DPA01.pdf
  • Ministry of Solidarity and Health https://solidarites-sante.gouv.fr/sante-et-environnement/activites-humanes/exposure-aux-ondes/article/effets-sur-la-sante-de-l-exposition -in-the-blue-light
  • 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 round table of March 16, 2013, 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.
  • Accumulation of lipofuscin in cultured retinal pigment epithelial cells results in increased sensitivity to blue light irradiation", Free radic Biological Medicine, 1997.
  • Gianluca Tosini, Ian Ferguson and Kazuo Tsubota, "Effects of blue light on the circadian system and eye physiology", Molecular Vision, vol. January 22, 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, the 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. Paris Descartes University, France (Sorbonne University Faculty of Medicine, Physiology Department). Consulted in December
  • Light-emitting diodes caused retinal damage and its wavelength dependence in vivo". International Journal of Ophthalmology, Vol. 10, No. 2. 2017 Feb 18. 9, 201