A sustainable world requires darkness at night

Abstract

Multiple environmental challenges face today’s world. One of the most damaging but least widely recognized arises from artificial light at night (ALAN). Light pollution is now known to be harmful to human health, mainly through disruption of hormone production and of human circadian rhythm, which causes sleepless nights, depression, anxiety, hypertension, diabetes and contributes to some types of cancer. ALAN is also bad for the environment. Almost all species of animals and plants are adversely impacted by light pollution, and not just nocturnal animals. Light pollution also wastes large amounts of energy, and as much as 35% of exterior lighting energy costs could be saved by better lighting. Light pollution also prevents astronomers and astrotourists being able to see so many stars. Astrotourism is booming in several countries and is beneficial for the local economy, especially so in parts of New Zealand, but this niche form of tourism is endangered by ALAN.