Michael discusses with Catherine Pérez Vega the question: Is light a pollutant? Catherine is researching the effects of artificial light on organisms and there is little doubt that it is. And there’s little doubt that it affects the organisms called humans, as well. Obviously modern society needs some artificial light at night, but all the other organisms don’t. As Catherine says, “how do we apply artificial lighting for our benefit, but at the same time take care of the night time?” Catherine is currently a Doctoral candidate in Biology at Freie Universität Berlin, Germany with her research taking place at the Light Pollution and Ecophysiology research group of Leibniz Institute for Freshwater Ecology and Inland Fisheries (IGB). Her work involves the interphase of ecology and architectural lighting to mitigate environmental solutions for urban lighting design applications.