Artificial light is bad for our eyes

Hello, autumn: how does artificial light affect your health?

Mobil-e: Dr. Wish, you divide light into “good” and “bad” - what is that all about?

Dr. Alexander wish: Good light is characterized by the fact that our genes have got used to it and adapted in the course of evolution. The body can therefore derive important control signals from certain areas of the natural light spectrum that the organism urgently needs in order to remain healthy and productive in the long term. These control signals tell our organ system whether it is outside day or night, summer or winter, warm or cold, cozy or dangerous. But there is also light that our organism does not know from the course of evolution, and that it could not get used to on a regulatory level. This includes in particular the cold light from modern artificial light sources, for example white LED light, or the light from background lighting in smart devices, TVs and computer monitors. By the way, good light can also turn into bad light, for example when too much sunlight causes sunburn.

Mobil-e: How does bad light affect people?

Dr. Alexander wish: The correct use of light is just as important for health as good nutrition, clean air and enough exercise. Diseases of civilization such as high blood pressure, diabetes, obesity and even cancer are favored by too little daylight and too much artificial light.¹ Humans absorb light both through their eyes and through their skin. In poor light it can happen, for example, that the eye suggests effects that the light cannot achieve on the skin and the body. Bluish-bright light signals the presence of UV radiation to the organism through the eyes. If this is then missing in the light that hits the skin, the body reacts incorrectly, triggered for example by the formation of stress hormones that were produced unnecessarily.

Mobil-e: What special effects does the lighting of televisions, computers and cell phones have on health?

Dr. Alexander wish: Almost all displays today are equipped with LEDs for backlighting. However, our eyes are not designed to stare into an active light source for hours every day. The light spectrum of such devices can damage the eyes and the endocrine system in the long term. Some of the negative effects can be traced back to the increased blue component, another part to the lack of near-infrared light. The near-infrared component is just as strongly represented in sunlight as visible light, so it is part of our natural radiation environment. In light medicine it is known that near infrared improves cell regeneration and effectively accelerates wound healing. Since this useful spectral range is missing in LED light, the potentially harmful blue light components are doubly problematic.

Mobil-e: How can you protect yourself against it?

Dr. Alexander wish: Wearing yellowish tinted blue light safety glasses has a positive effect on the endocrine system and eye health. According to recent studies, software solutions to reduce the blue light in screen light are less effective.² In addition, screen work should be regularly interrupted and, if possible, not take place in the evening.

Mobil-e: And what should you generally consider when it comes to lighting at home and at work?

Dr. Alexander wish: Most people today get too little real, unfiltered daylight and too much artificial light in the evening or at night. In order to do something good for your health, you should only use so much artificial light that a good orientation in the room is possible - no more. Candlelight is ideal, but real incandescent lamps and halogen lamps also produce a spectrum that comes close to natural conditions. If you have to switch to LEDs, you should pay attention to a warm light color of less than 2700 Kelvin and a high color rendering with a CRI / Ra value of more than 95. In addition, LEDs should be flicker-free. Energy saving lamps containing mercury are generally not recommended. The position of the light sources also plays an important role: while in nature the bright light comes from above during the day, the light sources should shine from the front or below in the evening.

(1) Source: Studies by the internist and ophthalmologist Prof. Fritz Hollwich, which he published in his book "Influence of Ocular Light Perception on Metabolism in Man and Animal".

(2) Source: Study "Does the iPad Night Shift mode reduce melatonin suppression?"