Ecological Effects of Artificial Light at Night

Artificial light at night (ALAN) has emerged as a pervasive environmental pressure that disrupts natural light–dark cycles, with cascading effects on organisms and ecosystems. At the organismal level, ALAN alters physiological processes such as circadian rhythms, hormonal regulation and photosynthesis, and interferes with behavioural cues governing foraging, predator–prey interactions, pollination and reproduction. In nocturnal insects, aberrant flight responses to lights can lead to increased mortality and reduced pollination services, while in plants, night‐time illumination can shift phenological events such as bud break and flowering. In aquatic and riparian habitats, skyglow and direct lighting penetrate water bodies, disrupting the diel vertical migrations of zooplankton and altering nutrient cycles. At the community and ecosystem scales, these individual perturbations can undermine biodiversity, restructure food webs and impair ecosystem services, including pest control, nutrient retention and carbon sequestration. Emerging research highlights the importance of spectral composition, light intensity and temporal patterns in shaping responses across taxa. Mitigation measures—such as dimming schedules, directional fixtures and spectral management—offer practical pathways to reconcile human lighting needs with ecological integrity.

Research from Nature Portfolio

Recent studies have elucidated mechanistic and landscape-scale dimensions of ALAN. High-resolution tracking has revealed that nocturnal insects navigate not by direct attraction to lights but via a conserved dorsal-light response, causing insects to steer perpendicularly around light sources and become trapped in continuous circuits. This guidance model clarifies long-standing questions about erratic flight patterns and suggests targeted interventions in lighting design. On a broader scale, international monitoring of skyglow has documented variations spanning four orders of magnitude between rural and urban settings and has shown that cloud cover can amplify sky brightness by factors of two to eighteen. These findings underscore the heterogeneity of light pollution and the need for long-term, standardised monitoring to inform global conservation strategies.

Ecological Effects of Artificial Light at Night publication trend

The graph below shows the total number of articles in ecological effects of artificial light at night across all publications each year (not limited to Nature Index journals).

Technical terms

Artificial light at night (ALAN): Human-made illumination during hours of natural darkness that alters organismal and ecological processes.

Skyglow: Diffuse illumination of the night sky caused by scattering of artificial light through the atmosphere.

Phenology: The timing of seasonal biological events such as flowering, migration or reproduction.

Riparian ecosystems: Habitats adjacent to rivers and streams that support distinct plant and animal communities.

Crepuscular: Describing organisms that are most active at dawn and dusk, when light levels change rapidly.

References

1. Why flying insects gather at artificial light. Nature Communications (2024).
2. Do rivers get sufficient sleep—A global analysis of light pollution in rivers. Resources Conservation and Recycling (2024).
3. The impact of artificial light at night on nocturnal insects: A review and synthesis. Ecology and Evolution (2018).
4. Ecological effects of artificial light at night on wild plants. Journal of Ecology (2016).
5. Human alteration of natural light cycles: causes and ecological consequences. Oecologia (2014).
6. Worldwide variations in artificial skyglow. Scientific Reports (2015).
7. Cloud Coverage Acts as an Amplifier for Ecological Light Pollution in Urban Ecosystems. PLOS ONE (2011).
8. Artificial light pollution: are shifting spectral signatures changing the balance of species interactions?. Global Change Biology (2013).