Now research shows the night is getting even brighter. From 2012 to 2016 the earth’s artificially lit area expanded by an estimated 2.2 percent a year (map), according to a study published last November in Science Advances. Even that increase may understate the problem, however. The measurement excludes light from most of the energy-efficient LED lamps that have been replacing sodium-vapor technology in cities all over the world, says lead study author Christopher Kyba, a postdoctoral researcher at the German Research Center for Geosciences in Potsdam. VIIRS satellite cannot see the short-wavelength blue light produced by white LEDs. This light has been shown to disrupt human sleep cycles and nocturnal animals’ behavior.
— source scientificamerican.com