More than half of all animal species are nocturnal, and this DW documentary follows the scientists trying to measure what artificial light is doing to them. In Berlin, ecologist Franz Hölker of the Leibniz Institute of Freshwater Ecology and Inland Fisheries runs Germany's largest light pollution field experiment, recruiting citizen scientists to catch, identify, and count aquatic insects drawn to streetlamps and dying in the process. At the Wadden Sea National Park, one of Europe's last truly dark regions, park director Peter Südbeck tracks migratory birds thrown off course by light from ships and offshore drilling platforms, some growing too exhausted to reach their feeding grounds. Night-time footage of light-drenched cities, industrial sites, and coastlines makes the scale of the problem visible in a way statistics alone cannot. The film treats light pollution as an underestimated driver of biodiversity loss, moving between lab work, field surveys, and interviews with researchers pushing for policy that would restore real darkness to the landscape.