CITIES WERE A MISTAKE:

The International Dark Sky Association, an Arizona-based NGO, estimates that about one-third of all outdoor lighting burns at night without benefit. Even before the energy crisis and higher prices, shutting off this fruitless lighting would save $3 billion (€2.9 billion) a year.

Since fossil fuels are still the main source of energy worldwide, simply switching off useless lights helps reduce air pollution and harmful emissions.

In India, for example, extreme lighting emits 12 million tons of CO2 per year, according to Pavan Kumar of the Rhani Lakshmi Bai Central Agricultural University in the state of Uttar Pradesh.

That's about half as much as the country's total air and sea traffic per year. 

Today, more than 80% of people worldwide live under light-polluted skies. In Europe and the US, the figure is as high as 99%, meaning people no longer experience real darkness.

Sufficient darkness at night is also good for health. Studies have demonstrated the link between artificial light and eye injury, sleeplessness, obesity and in some cases depression.

Much is related to melatonin, a hormone that is released when it gets dark.

"When we don't get that hormone, when we don't produce that hormone because we're exposed to so much light in our apartment, or as a shift worker, then the whole working of this biological clock system becomes problematic," said Christopher Kyba, a scientist at the Potsdam-based German Research Center for Geosciences.

A 2020 study from the US shows that children and adolescents who live in areas with a lot of artificial light get less sleep and suffer more often from emotional problems.

The introduction of artificial light is "one of the most dramatic changes we've made to the biosphere," said Kyba. 

Tweet   @brothersjudd