Is blue light really harmful?

Blue light: how harmful is it really?

Whether on the smartphone, at work in front of the computer or in front of the television in the evening. LED technology now surrounds us all day. The problem: Artificially generated blue light is suspected of having a negative impact on our health. But is it really that harmful to humans and can you protect yourself from it? We explain what is important.

Blue light: how harmful is it really?
Blue light: how harmful is it really?

The most important things at a glance


How harmful is blue light?

Anyone who is exposed to blue light for a long time runs the risk of damaging receptors in the eyes and thus also destroying the retina. Blue light also has a negative impact on our sleep.

Where is blue light contained?

Blue light is contained in natural sunlight and regulates our biological clock. In the meantime, screens, computers, tablets and smartphones also emit artificial blue light around the clock.

How does blue light affect people?

Blue light has a major impact on our biological clock and our hormonal balance. The hormone melatonin plays a major role here, influencing how and when we feel tired. If we are increasingly exposed to blue light, it prevents us from falling asleep.

What is blue light

For humans, blue light belongs to the visible part of the electromagnetic spectrum, which extends over the range from approx. 380 nanometers to 780 nanometers. The spectrum of blue light is around 380 nanometers in the blue-violet range and extends to around 500 nanometers, where the blue light turns green.

Blue light has surrounded us not only since the invention of computers. Rather, it is a component of sunlight with around 25 to 30 percent and has an important influence on our sleep-wake cycle. As long as we are exposed to blue light, we stay awake and fit because it suppresses the sleep hormone melatonin.

Why are we more exposed to blue light?

Due to the growing number of digital devices in our everyday life, we are no longer just exposed to the natural blue light of the sun, which disappears at dusk at the latest. Rather, artificially generated blue light surrounds us around the clock. It starts with looking at the smartphone in the morning and continues throughout the day.

According to the Nielsen Total Audience Report: Q2 2017, the average adult in the United States spends 10 hours and 48 minutes a day consuming media. 8 hours and 58 minutes take place in front of a screen. It is more than problematic that modern devices and lamps emit a significantly higher proportion of blue light (35 percent) than sunlight. This means we are exposed to the potentially harmful blue light for a much longer period of time. And that won't change much in the future either. On the contrary: More and more people are dependent on working in front of a screen in their job.

How does blue light affect people?

As early as the summer of 2018, researchers warned against blue light in an article by the US University of Toledo in the journal Scientific Reports. It would damage the eyes very severely and in the worst case even lead to blindness. Many scientists have questioned this, claiming that the retina has natural protective mechanisms against the damage caused by light. So it remains controversial to what extent blue light is really harmful to humans, because there are no long-term studies on humans on this subject. Nevertheless, experts suspect that the high-energy light from the screens cannot have a positive influence on health in the long term. The following damages and problems are suspected to be caused by blue light:

  • Damage to the retina of the eye

At present, the influence of blue light on the eye is only being investigated on the basis of animal experiments. Even so, it is believed that blue light triggers photochemical stress in the human eye that damages the retina. The retina has a layer of pigment cells called the retinal pigment epithelium (RPE) that is supposed to protect the retina. However, if eyes are constantly exposed to blue light, protection is no longer given and not all blue wavelengths can be absorbed - the retina is damaged. In addition, the blue light probably accelerates age-related macular degeneration, which should actually only occur in humans from the age of 60.

The scientific findings on the influence of blue light on sleep are more extensive. The natural blue light of the sun actually influences our internal clock, the so-called "circadian system". We wake up in the morning to the blue light of the sun and the red tones of the evening sky ensure that melatonin is released and we feel tired in the evening. If we are exposed to blue light all day long, our normal rhythm gets mixed up and we have difficulty falling asleep in the evening. If we are plagued by insomnia for a long time, this can lead to other mood disorders such as depression. Scientists also suspect that the interruption of our circadian rhythm means that the body can no longer repair DNA as well and thus increases the risk of cancer.

Benefits of blue light

Although blue light is viewed more critically nowadays, humans have also made use of its positive properties. For example, light therapy with blue light can help people with winter depression. Anyone who sits near a daylight lamp for an hour every morning should feel an improvement in symptoms after a few days. It has already been scientifically proven that light therapy is successful.

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This is how you can protect yourself from blue light


Blue light filter glasses

If you have to work in front of the computer all day, you can protect yourself by wearing glasses with a blue light filter. But be careful, there is a large selection of blue light filter glasses. When buying, make sure that the model complies with the European standard for eye protection - EN166. Glasses from the USA or Asia are usually of a lower standard.

In addition, a distinction is made between two types of filter goggles: The edge filter goggles completely filter out light from a certain frequency range, they usually have yellow-orange lenses and are similar to ski goggles. The exact tint depends on the exact color that is to be filtered out. As a rule, these glasses are worn by people who have severe visual impairment or who already have diseases of the eye. For healthy people, filter glasses that only weaken the blue light are sufficient. They are a little more subtle, let through less blue light and only have a tint of a maximum of 10 percent - perfect for everyday use.

Reduce blue light in the evening

Even if it is difficult to avoid the blue light during the day, it can be helpful to avoid it completely in the evening. So, for example, put your cell phone aside from 7 p.m. and don't watch TV for a change. Your eyes will thank you for it, and you should get a better night's sleep as a result.

Set the blue filter

The developers of modern operating systems have long recognized that blue light can be harmful. That is why a blue filter has been integrated into most smartphones and devices, which you can switch on if necessary. They are called "Nightshift" on Mac OS or "Night Mode" on Android smartphones and make it possible to reduce blue light emissions.