A streetlight right in front of your house may make it easier to safely get in the door at night – but good luck trying to sleep without heavy curtains. This is just one example of how artificial light is useful in many aspects of our daily lives, as well as a major problem.
Our world is illuminated by more artificial light than ever before. A recent US study found that nighttime artificial light emissions are expected to increase by about 16% globally from 2014 to 2022. According to research published in Nature.
Areas experiencing greater brightness also saw an average 9% increase in light intensity.
Too much artificial light can make us sick
We can turn off light sources like computers, phones, TV and lamps ourselves. But other sources are beyond our control: streetlights, headlights on cars, illuminated monuments, glowing billboards, and spotlights on construction sites, storefronts, bus stops, parking lots, playgrounds, and stadiums, just to name a few.
Exposure to artificial light to this extent can disrupt our natural sleep-wake cycle, destabilize our hormonal balance and increase the risk of metabolic disorders like diabetes, depression and obesity.
The color of light also has an impact. The cooler or whiter the light, the more it resembles daylight – and the more it suppresses the hormone melatonin, which makes us feel sleepy in the evening.
No other environmental condition has remained unchanged over the millennia like the natural light of the Sun, Moon and stars. All living things have adapted to this rhythm. More than half of all species are nocturnal – if the nights became brighter, it could have disastrous consequences.
Migratory birds use the moon and stars for navigation. Artificial light can distract them and send them off course, leading to disorientation and exhaustion. Other birds may be tricked into laying eggs too early in the season, when there are not enough insects for the newborn chicks to eat.
Insects such as moths and beetles use light from the starry night sky to find food and mating partners. But artificial light is brighter and inevitably attracts them. They keep circling the light source continuously until they get exhausted and fall to the ground, dead. Billions of people are killed this way every year, a devastating toll when insects are already at risk from pollution, declining biodiversity and other threats.
Nocturnal mammals such as elephants and bats generally avoid well-lit areas; In our bright world, their habitat is constantly shrinking. And light can create an artificial barrier that some fish species will not be able to cross. For example, light falling on the surface of the water from a huge bridge can prevent eels from swimming – a major problem during their migratory breeding season.
Brightest night sky in China, India
Nature The study found that the increase in night-time light emissions since 2014 was greatest in Asia, particularly in economically growing regions of China and India.
In the United States, light pollution has increased the most on the West Coast due to the growing economy and population in cities in California. In contrast, the East Coast and parts of the US Midwest have become darker – partly due to shrinking industrial zones, fewer residents and more energy-efficient lighting.
In Europe, overall light intensity has decreased by 4% compared to 2014, with researchers observing a decline in light pollution across the region. The decline was most noticeable in France (33%), the United Kingdom (22%) and the Netherlands (21%).
Unlike the United States, dark night skies in Europe are not always the result of economic decline.
For example, in France, new bylaws now mandate that lights in all commercial buildings, storefronts, parking lots, public parks and cultural heritage sites be turned off by 1 a.m. at the latest.
Other European countries had long taken up the issue of brightening the night sky. The Czech Republic passed the world’s first law against light pollution in 2002, which stipulates, among other rules, that streetlights can only be directed toward the ground, with a fine of no more than €3,000 ($3,500).
Slovenia has been combating light pollution since 2007 by limiting annual electricity consumption for lighting to 50 kilowatt hours per inhabitant. Other rules also ensure that street lights do not shine too brightly at night in residential areas.
Germany’s ‘star city’, Fulda, lights the way
Germany has not yet passed any nationwide regulations against light pollution. However, the Federal Nature Conservation Act is currently being updated in an attempt to curb this. At the state level, Baden-Württemberg has already passed a law that bans masked lights from April to September – the months when wildlife is most active in Germany.
The city of Fulda, about 100 kilometers (60 mi) north-east of Frankfurt, is a leader in lighting. Fulda Cathedral is illuminated with precisely aimed spotlights instead of standard floodlights. In new neighborhoods outside the city centre, walkways and cycle paths are only 20% illuminated; When someone arrives, motion detectors bring the street lights to maximum for a brief period.
“Insect traps installed before and after implementing these measures showed that the new lights kill 90% fewer insects,” said Marcel Sire, an environmental engineer at Fulda’s city planning department. He said Fulda is starting to install new street lights in the city by replacing old lamps as needed to keep costs down.
Fulda has been recognized for her efforts to bring back the night. DarkSky International, a US-based non-profit raising awareness of the harmful effects of excessive artificial light, named the city as Germany’s first “Star City” in 2019. 11 other certified locations in the country “With excellent dark sky conditions and safety practices.”
bring back the firefly
As shown in the Czech Republic, Slovenia and Fulda, lights should illuminate only where absolutely necessary – for example, walkways, and not the entire night sky. Motion sensor controlled lights are a great alternative to outdoor lights that are always on.
The warmer the light, the less harmful it is – to humans and other creatures. Conservation organizations recommend using a light temperature of no more than 3000 Kelvin for outdoor lighting, the warm, yellowish-white light that is typically used in living rooms and bedrooms.
Following these recommendations can help return fireflies to our parks and gardens. Fireflies are another insect threatened by light pollution; artificial light prevents male and female insects from finding each other.
Simply closing the curtains in your home at night can not only help block out any annoying outdoor glare, but also prevent indoor lights from disrupting the outdoor nightlife.
This article was originally written in German.