Environmental Impacts of Artificial Light at Night

The nighttime is undergoing unprecedented change across much of the world, with natural light cycles altered by the introduction of artificial light emissions. Here we review the extent and dynamics of artificial light at night (ALAN), the benefits that ALAN provides, the environmental costs ALAN creates, approaches to mitigating these negative effects, and how costs are likely to change in the future. We particularly highlight the consequences of the increasingly widespread use of light-emitting diode (LED) technology for new lighting installations and to retrofit pre-existing ones. Although this has been characterized as a technological lighting revolution, it also constitutes a revolution in the environmental costs and impacts of ALAN, particularly because the LEDs commonly used for outdoor lighting have significant emissions at the blue wavelengths to which many biological responses are particularly sensitive. It is clear that a very different approach to the use of artificial lighting is required.

Automated summary

The global changes in nighttime are due to the introduction of artificial light sources, altering natural light cycles. LED technology, in particular, has significant environmental costs and impacts on nighttime lighting, requiring a different approach to artificial lighting use.