LIGHT POLLUTION

The effects of light pollution on people and nature

Light pollution, or light smog, refers to the general brightening or illumination of the night sky. Particularly in Western Europe and North America, there are hardly any areas left where the night sky is not illuminated by artificial lighting. This applies, of course, mainly to the urban areas where most people live. By 2016, 83% of the world’s population was already affected by light pollution. Overall, the problem is increasing by 5–6% per year.

WHERE DOES LIGHT POLLUTION COME FROM 

Permanent illuminated signs, large industrial plants, street lighting and infrastructure, sports facilities, etc. All of these contribute to the fact that, even on a clear night, the stars are barely visible above cities. But of course, every living room, every lit garden and every terrace plays a part too. And as our daily rhythms have shifted further and further into the evening over the last few decades, we are turning night into day. Especially in densely populated areas. 

A large proportion of light pollution can be attributed to poorly planned and executed outdoor lighting. This includes public buildings and spaces, as well as street lighting installed without any plan or direction. Often, the saying ‘more is better’ is applied in places where it makes absolutely no sense.

THE IMPACT OF LIGHT POLLUTION 

The consequences of constant lighting are serious – artificial lighting alters entire ecosystems. Day and night, light and dark, act as a metronome and a timekeeper for nature. The chronobiological rhythm of plants, animals AND humans is geared towards this constant cycle. Plant growth cycles are disrupted by light pollution; diurnal and nocturnal animals struggle, and life falls out of sync! 

• Diurnal creatures / humans
  Disrupted night-time rest, sleep disorders that can lead to chronic sleep deprivation; sleep deprivation leads to physical limitations and possibly even illness 
• Nocturnal creatures
  More than 60% of living creatures are nocturnal! Continuous night-time lighting disrupts all aspects of life: foraging, predator-prey relationships, reproduction, pollination, etc.

CONSEQUENCES FOR NATURE

It is actually insects that bear the brunt of light pollution. Of course, one might say, ‘Yay, no more midges or mosquitoes!’ But the negative effects are clearly measurable and noticeable. Not only because the light sources become death traps for these little creatures. Insects are among the most important pollinators in the plant world, are the largest source of food for the animal kingdom and, increasingly, for humans too, and they are vital beneficial organisms in agriculture!

Insect decline therefore has more than one consequence: 

• Reduced food supply for animals 
• A reduction in biodiversity in flora and fauna 
• Crop failures and losses in agriculture, with consequences for humans

Birds and fish also suffer from light pollution. Migratory birds and schools of fish near the coast sometimes lose their sense of direction. Native bird species are altering their nesting and breeding behaviour. This creates a vicious circle, as breeding too early in spring means there is less food available when plants and insects are not yet sufficiently abundant. Species extinction is inevitable. 

HUMANS SUFFER 

We humans now spend more and more time in a kind of twilight, without the proper alternation of day and night. During the day, we need bright daylight to kick-start our bodies and metabolism. Vitamin D deficiency – the ‘sunshine vitamin’, which can only be produced by daylight – has become a widespread condition. At night, however, we have too much light around us. To produce the sleep hormone melatonin, which helps us wind down and puts the body into sleep phases, we need darkness. That is why melatonin is also called the ‘darkness hormone’. However, melatonin not only regulates sleep, but also other bodily functions such as regeneration processes and cell renewal. Sleep and wake phases are often blurred, and the rhythm of our internal clock is permanently disrupted.

The consequences: sleep disorders, sleep deprivation and a hormonal imbalance. Taken together, these can lead to physical and mental health problems, ranging from diabetes to depression. 

The rule is: to maintain a healthy sleep-wake cycle, we should avoid bright and, above all, cold light for 1 to 2 hours before going to bed. So, when it comes to lighting at home, opt for light sources with a warm color of light. Or use dimmable and adjustable light sources. Televisions, monitors and mobile phone screens, with their predominantly bluish light, are not particularly conducive to melatonin production. Even though many devices nowadays use a blue light filter to shift the light spectrum of their screens into the warmer range.

WHAT CAN WE DO ABOUT LIGHT POLLUTION? 

We now know what we can do for ourselves at home. But what about in public spaces? In Bavaria, for example, a law has been in place since 2019 stipulating that public buildings may only be lit until 11 pm. A good start! Smart LED lighting solutions are also on the rise; sensor-controlled systems, for instance, can help improve the situation. Street lighting can be designed to be targeted and shielded. Fewer streetlights are needed, and they are more effective. Sports facilities do not need to be lit up all the time either. Illuminated advertising also poses a major problem. Here too, a time limit could help, although many industries will resist this.

As with many things, there is another side to the coin: whilst LED solutions do lead to massive reductions in emissions and energy consumption, they also result in more of them being used – after all, they save money and electricity. This does not provide a lasting solution to the problem of light pollution. 

Yet all we really want is to be able to look up at the sky at night and try to count the stars. Soon, however, this will only be possible in very few places around the world.