Too much Light and the Loss of Night

Across Europe, and in Germany, many people wonder where all the stars have gone. The fact is, the stars have not disappeared, but rather the increase in reflected artificial light reduces the radiance of the stars. This situation has developed over a long period of time and despite the illumination of our night environment having many advantages we are slowly becoming aware of the disadvantages, that is, of light pollution. Light pollution is on the rise and we are uncertain about its effect on humans and our environment.

A recent research project “Loss of the Night” (Verlust der Nacht) is a multi-disciplinary platform where biologists, physicists, lighting engineers, town planners and humanities scholars are jointly exploring the consequences of the “pollution of natural light” and the “loss of the night” for human beings and nature.

The project is being coordinated by Dr Franz Hölker, a biologist from the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Berlin.

There are many effects of light pollution which are, as yet, not well understand. One of the most important is how light pollution disrupts biological rhythms. While effects on humans are less clear, laboratory studies have already established that even a 1 lux increase in light (roughly the equivalent of the light emitted by a candle at a distance of 1 metre) produces a hormonal effect in fish. This has implications for humans (who, like fish, produce the hormone melatonin), but it also means that this may disrupt the rhythms of all organisms such as fish where reproductive and hunting/feeding behaviour is based on the inner clock regulated by melatonin.

A further implication is that artificial light at night has an impact on biodiversity as many insects and organisms are attracted to lighting and are therefore absent from the waterways and locations they would normally inhabit which may therefore disrupt the food chain.

One of the aims of the project, in addition to understanding the impact of light pollution on humans and out environment is to establish guidelines for the use of light in a sustainable and responsible manner.

The project “Loss of the Night” is funded by the Federal Ministry of Education and Research (BMBF). Here is the project website.

Photo credit: “”. Material used in the preparation of this article has been drawn from Research in Germany.


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