Artificial Light at Night: State of the Science 2025

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 orbit- ing the Earth (Section 7). Finally, it concludes with a discussion of the knowledge gaps that exist within these topics and the re- search questions whose answers can fill the gaps (Section 8). It is intended to be useful to those seeking to broaden their under- standing of research on the causes and consequences of artificial light at night.