Artificial lights are eating away at dark nights – and that's not a good thing

"This is concerning, of course, because we are convinced that artificial light is an environmental pollutant with ecological and evolutionary implications for many organisms – from bacteria to mammals, including us humans – and may reshape entire social ecological systems," Franz Holker of the Leibniz-Institute of Freshwater Ecology and Inland Fisheries, one of the study's authors, said in a briefing.

Thanks to electric lights, outdoor lighting grew at a rate of 3% to 6% annually in the second half of the 20th century. While this has benefited human productivity and safety, it has come with a dark side: The night is no longer dark enough.