Blue light: Controversial glow

Blue light is playing an increasingly important role in our everyday life. Studies show: it also affects our health

Many screens use LEDs with a high proportion of blue light

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Smartphones, wafer-thin tablets, modern computer screens and flat-screen televisions - they are inconceivable without modern LED technology. Energy-saving light-emitting diodes no longer dominate the lighting of streets and our living spaces.

Indications of damage to health

If we look at glowing screens at close range for many hours and are constantly in an environment lit by LEDs, this is not without consequences: everyone has probably had tired, dry eyes at some point.

Scientists, however, suspect far more unpleasant consequences: Myopia is increasing dramatically, some studies indicate that the high proportion of blue light in LEDs can damage the retina, and there is even discussion of a connection between nighttime lighting and some types of cancer.

The higher the educational qualification, the more myopic?

More and more people in Europe are short-sighted. According to a study in European Journal of Epistemology Around 47 percent of 25 to 29 year olds now suffer from so-called myopia, but only 28 percent of 55 to 59 year olds.

And the Gutenberg health study comes to the conclusion that 53 percent of university graduates are short-sighted, but only just under a quarter of people without training or a high school diploma.

Experts justify the connection with the fact that young people spend a lot of time indoors at school and university, staring for hours at books and increasingly also at smartphones and tablets.

A question of usage

"Myopia has something to do with the growing eye, among other things," explains Professor Olaf Strauss from the field of experimental ophthalmology at the Charité in Berlin.

"If you often fixate on nearby objects while the eye is still growing, the eyeball can grow longer," says the retinal researcher. "Then the sharp image does not appear on, but just in front of the retina."

However, myopia has nothing to do with the LEDs in smartphones. Rather, the usage behavior is decisive. However, there is another property of light-emitting diodes that is of concern to many experts: the high proportion of blue light.

More light, less perspective

Many epidemiological studies show that too much is generally dangerous and can damage the macula. This is the area of ​​sharper vision where a particularly large number of light-sensitive cells, the photoreceptors, are concentrated.

Scientists from the INSERM research institute have now tested the effect of different light sources at different intensities in a laboratory experiment. It was shown that the blue light component of the LEDs already causes defects in the macula at an intensity of 500 lux - this corresponds to the usual brightness in living rooms.

Although the researchers did not work with real test persons, Professor Albert J. Augustin, Director of the Eye Clinic at the Karlsruhe Municipal Clinic, says: "I believe that these results can and must be transferred to humans."

A corresponding study on humans would hardly be feasible and ethically unjustifiable.

Photoreceptor cells die earlier

"The bundled light falls on the retina and reacts there with the abundant oxygen," explains Olaf Strauss, explaining how the high-energy blue light affects our visual cells. "This creates toxic compounds from the cells' metabolic products, which accumulate over a lifetime and damage cell components."

As a rule, photoreceptor cells would only die from the age of 60 and age-related macular degeneration could occur - a permanent shower with high-energy light would accelerate this process.

Suspicion: the risk of cancer increases

And modern lighting may also harbor other risks: A study published in April with more than 4,000 participants between the ages of 20 and 85 from eleven regions of Spain raises the suspicion that blue light could promote the development of some forms of cancer.

The researchers had analyzed the data of breast cancer patients and prostate cancer patients, compared them with healthy control persons and recorded how intensively the respective persons were exposed to blue light in the outdoor area and in the house.

The result: In people who lived in a blue-light environment, the risk of breast cancer was 1.5 times higher and the risk of prostate cancer was twice as high.

LED disturbs sleep

According to the Spanish scientists, an increased dose of blue light before going to bed suppresses the formation of the hormone melatonin, which controls the sleep-wake cycle. Other studies show that a melatonin deficiency could be related to hormone-dependent tumors such as breast or prostate cancer.

The Spanish study does not provide any proof of this mechanism, it merely establishes a statistical link and not a causal chain. That is the main problem with such observational studies: that one cannot clearly separate different possible causes from one another.

Because people who stay up late at night or do shift work often have different eating habits or a different health awareness than the average.

Experts expect political intervention

Nevertheless, people are worried, as can also be felt at the Cancer Information Service (KID) of the German Cancer Research Center in Heidelberg: "We receive many inquiries as to whether night light, shift work or the use of cell phones or tablets at night might increase the risk of cancer," says KID employee Dr. Birgit Hiller.

"But the studies to date are too contradictory and there is no certainty about the actual relationships."

In view of the possible dangers posed by modern light sources, eye specialist Augustin sees the legislator as having an obligation: "Actually, the authorities in Brussels would be asked to work towards ensuring that the LEDs have a lower blue component."

Get active yourself

But everyone could do something themselves, for example, do without the light-emitting diodes at home or use glasses that reduce the blue component. There are already normal, non-tinted glasses that can reduce the amount of light in the house.

Olaf Strauss believes it is sufficient in the home to equip yourself with so-called warm white LED lamps: "With these, the blue light component is significantly reduced. The heat of the light is indicated in Kelvin on the packaging; I would have no concerns with a color temperature below 3000 Kelvin . "

Avoid blue light before going to sleep

Most experts, on the other hand, consider the relatively low proportion of blue light in smartphones, screens or television sets to be hardly dangerous for the retina. In the evenings, however, the devices should not be used in the room without additional lighting. Because in a dark environment the pupils dilate and more blue light can fall on the retina.

Many computers and cell phones therefore now have a special night mode in which the blue light component is reduced and the image appears in a warmer, yellowish tone. This has another advantage: If you check the last news of the day in the slumber, you can fall asleep more easily.