Denmark is testing a new type of streetlight that changes color instead of brightness. In Gladsaxe, near Copenhagen, red lights now replace white lamps along parts of Frederiksborgvej. This change aims to protect local bats while keeping the roads safe for people. Bats live in this area, and studies show bright white or blue lights disturb their movement and feeding. Research from the Netherlands found red light disrupts bats less and helps them hunt insects better. The municipality didn’t want to turn off lights because of safety concerns. Red was chosen as the best compromise. Warm white lights are still used at busy junctions and crossings for visibility. Jonas Jørgensen, road engineer in Gladsaxe, said, "The goal was to limit disturbance without reducing accessibility." He added that darkness would be ideal for bats but not practical for public roads. Lighting experts see this as a test to rethink city lights. Philip Jelvard from Light Bureau said, "The red light also carries symbolic weight, signalling that the area is environmentally sensitive." Gladsaxe follows the UN Sustainable Development Goals. Mayor Trine Graese said, "The project shows how infrastructure can support both human needs and animal welfare." It’s a small change with a big message. Currently, the red streetlights are only on one road with no plan to expand yet. Still, urban planners globally watch closely as cities seek ways to protect nature while lighting streets safely. Denmark’s experiment shows that city lights can be gentler on wildlife without leaving people in the dark.