This briefing summarizes the current state of knowledge about how the widespread and growing use of artificial light at night interacts with six key topics: the night sky (Section 1); wildlife and ecology (Section 2); human health (Section 3); public safety (Section 4); energy security and climate change (Section 5); and social justice (Section 6). It also includes a discussion of the emerging threat from light pollution caused by objects orbiting the Earth (Section 7). Finally, it concludes with a discussion of the knowledge gaps that exist within these topics and the research questions whose answers can fill the gaps (Section 8). It is intended to be useful to those seeking to broaden their understanding of research on the causes and consequences of artificial light at night.

The report is published by DarkSky International (formerly the International Dark-Sky Association; www.darksky.org) and written by the author on contract to DarkSky International.