Turning off the lights at night

Adrian, Switzerland, 15 years old

Over the years, we’ve all become more aware of different kinds of pollution. Generally, the media are full of stories about greenhouse gases, plastic and nuclear waste but overlook one of the most important sources of disruption to Swiss wildlife. Light pollution is destroying the Swiss nocturnal ecosystem but its consequences and damaging effects are too often ignored.

What is light pollution? This is a very pertinent question, since the general public knows very little. Practically speaking, it means the excess light from human activities that disrupts the natural ecosystem. It’s easy to see because we’re exposed to it all the time. In night-time photos, for example, you can often see a characteristic kind of light in the sky, known as “skyglow”. Satellite photos help us to understand the real scale of light pollution at the global level:

The nocturnal world seen from space

Don’t be distracted by this beautiful image: light pollution creates a wide range of problems. Lots of organisations have emphasised the impact on wildlife. A majority of migrating birds use natural light to help them find their destination. But the interruption caused by humans means many of them never finish their journey. In addition, first, some species of animals and insects are intimidated by artificial light. This creates nocturnal barriers they cannot cross, disrupting their life and reproductive cycles. Secondly, lots of insects are attracted by human light. These end up using their energy flying around a powerful source that will give them nothing in return, with a negative impact not only on the insect population but also the entire food chain.1

Animals are not the only things that suffer. Plants are affected too. Constant light transforms their behaviour. The day-night rhythm dictates the most important aspects of plant growth, such as when they flower or their leaves fall1, or how quickly they grow. It affects us too. According to, almost 35% of the energy used for all artificial lighting is lost. This represents an enormous financial and planetary cost, since excess greenhouse gases will have been produced to waste light.

The causes of light pollution seem – and in fact are – fairly obvious. Any light bulb can be guilty of it. However, it may be useful to specify the different sources to help us understand how to resolve the problem. In Europe, approximately 28% of light pollution comes from light used in advertising, 32% from industrial light and 40% from streetlights and cars.2 The huge percentage from streetlighting and vehicles is constantly blamed by organisations leading the fight against light invasion. In their view, one of the simplest and most effective ways of reducing our influence on the night is to change the type of streetlights we use.

Different kinds of streetlight and their impact on the night

It has been estimated that almost 50% of light energy is lost using the first model, while others vastly reduce this number.3

The best solution would be to eradicate artificial light completely for anything non-human, but it is clear that would be impossible. We do need light to drive cars at night, for example, and night-time lighting helps us feel safer. On the other hand, we could use a lot less light by installing reflective panels on streets to “recycle” the light produced by cars. One of the great illusions in this debate is the myth around safety and night-time lighting. In other words, fear of the dark.

According to Darksky, not only does night-time lighting not reduce the crime rate, it can compromise people’s health. The dazzle from streetlights that are too powerful or badly placed often leads to road accidents and visual difficulties for older pedestrians. It’s fair to say we will always need a minimum level of electrical light, but we shouldn’t overestimate its usefulness.

There are lots of solutions for the many problems caused by light pollution, but they are often complicated and hard to implement. The only universal truth is that we would benefit from turning off the lights at night, but the general perception of lighting is too positive to make it a reality across the canton. We are too dependent on the firelight that has given us an advantage over animals since the dawn of time. We need to persuade people not only that the dark is useful, but also explore the cultural angle that lies behind our fear of the dark. The virgin night is a landscape that should exist in all parts of Switzerland. This initiative has its romantic side, too. Fundamentally, a large number of light pollution activists are astronomy enthusiasts who want to see the stars better at night without interference from “skyglow”.

It takes a lot of people to alter how other people perceive things. In this case, where disinformation is such a problem, anyone can support the initiative simply by sending information to friends or posting on social media. Darksky Switzerland is a well-established organisation and an excellent example. Their actions have already motivated several communes to turn off the lights at night on several occasions, and all the experiments have been a success. Light pollution is an easy danger to address in practical terms. Changing the type of streetlights and the lighting in Swiss urban areas is not en enormous project and would really help minimise the negative effects. It’s simply about changing the views of Swiss citizens – and we can start by turning off the lights at night.

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– A Least-Squares Method for a Monge-Ampère Equation with Non-quadratic Cost Function Applied to Optical Design – Scientific Figure on ResearchGate. [accessed 15 Mar, 2021] [accessed 15 Mar, 2021]

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