Artificial light at night (ALAN) is a poorly studied but ubiquitous type of environmental pollution that has profound ecological, physiological, and societal consequences. This mini-review is a synthesis of existing knowledge about the causes and effects of ALAN. It highlights the variety of effects it has on both ecosystems and human health. Excessive or improperly directed outdoor lighting is defined as ALAN. It causes various effects, including disturbances to astronomical observations, wildlife behavior, and human circadian rhythms. The environmental effects consist of disrupted migration, breeding, and nesting behaviors of animals, insects, and birds, and reduced hatching rates of sea turtles and coral reefs around the coast. In humans, ALAN has been linked to cancer, especially breast cancer, metabolic disorders, and mood disturbances as a result of disruption to the circadian rhythm. Although there is an increasing level of awareness of the problem, both through digital distribution and grassroots movements, successful mitigation has yet to be achieved. Urban lighting is expanding at a rate of more than 2 percent per year. This review classifies the types of lights that contribute to ALAN, explores its oncogenic processes, and considers citizen-led efforts to curb light pollution. We emphasize that interdisciplinary research and policy intervention are urgently required to tackle the environmental and health aspects of ALAN and suggest a range of measures, including less nighttime lighting, implementing blue-light-blocking devices, and increasing environmental surveillance. The lack of funds and research priorities is an additional reason to create global activities aimed at saving natural darkness and reducing the overall impact of ALAN.
Artificial light at night, light pollution, circadian rhythms, ecological impacts, cancer, citizen action
B Marangoni, L. F., Davies, T., Smyth, T., Rodríguez, A., Hamann, M., Duarte, C., Pendoley, K., Berge, J., Maggi, E., & Levy, O. (2022). Impacts of artificial light at night in marine ecosystems—A review. Global Change Biology, 28(18), 5346. https://doi.org/10.1111/gcb.16264
Cesarz, S., Eisenhauer, N., Bucher, S. F., Ciobanu, M., & Hines, J. (2023). Artificial light at night (ALAN) causes shifts in soil communities and functions. Philosophical Transactions of the Royal Society B: Biological Sciences, 378(1892), 20220366. https://doi.org/10.1098/rstb.2022.0366
Chepesiuk, R. (2009). Missing the dark: Health effects of light pollution. Environmental Health Perspectives, 117(1), A20–A27. https://doi.org/10.1289/ehp.117-a20
Duarte, C., Quintanilla-Ahumada, D., Anguita, C., Manríquez, P. H., Widdicombe, S., Pulgar, J., & Quijón, P. A. (2019). Artificial light pollution at night (ALAN) disrupts the distribution and circadian rhythm of a sandy beach isopod. Environmental Pollution, 248, 565–573. https://doi.org/10.1016/j.envpol.2019.02.031
Gaston, K. J., Gaston, S., Bennie, J., & Hopkins, J. (2015). Benefits and costs of artificial nighttime lighting of the environment. Environmental Reviews, 23(1), 14-23.
Hahn, R. A. (1991). Profound bilateral blindness and the incidence of breast cancer. Epidemiology, 2(3), 208-209.
Hartley, R. (2023, July 11). Artificial light at night: State of the science 2023 report released. DarkSky International. https://darksky.org/news/artificial-light-at-night-state-of-the-science-2023-report/
Hölker, F., Bolliger, J., Davies, T. W., Giavi, S., Jechow, A., Kalinkat, G., Longcore, T., Spoelstra, K., Tidau, S., Visser, M. E., & Knop, E. (2021). 11 Pressing Research Questions on How Light Pollution Affects Biodiversity. Frontiers in Ecology and Evolution, 9, 767177. https://doi.org/10.3389/fevo.2021.767177
Hölker, F., Moss, T., Griefahn, B., Kloas, W., Voigt, C. C., Henckel, D., ... & Tockner, K. (2010). The dark side of light: a transdisciplinary research agenda for light pollution policy. Ecology and society, 15(4).
Horton, K. G., Nilsson, C., Van Doren, B. M., La Sorte, F. A., Dokter, A. M., & Farnsworth, A. (2019). Bright lights in the big cities: migratory birds’ exposure to artificial light. Frontiers in Ecology and the Environment, 17(4), 209-214.
John C. Wells Planetarium. (2025). Light pollution: The overuse & misuse of artificial light at night. James Madison University. https://www.jmu.edu/planetarium/light-pollution.shtml
Kocifaj, M., Wallner, S., & Barentine, J. C. (2023). Measuring and monitoring light pollution: Current approaches and challenges. Science. https://doi.org/adg0473
McDermott, A. (2023). Light pollution is fixable. Can researchers and policymakers work together to dim the lights? Proceedings of the National Academy of Sciences of the United States of America, 120(27), e2309539120. https://doi.org/10.1073/pnas.2309539120
Motta, M. E. (2024, October). We’re all healthier under a starry sky. AMA Journal of Ethics, 26(10), E804–E810. https://doi.org/10.1001/amajethics.2024.804
National Park Service. (2025, March 24). Synthesis of studies on the effects of artificial light at night. U.S. Department of the Interior. https://www.nps.gov/articles/effectsoflight.htm
Oyabu, A., Wu, L., Matsumoto, T., Kihara, N., Yamanaka, H., & Minamoto, T. (2024). The effect of artificial light at night on wild fish community: Manipulative field experiment and species composition analysis using environmental DNA. Environmental Advances, 15, 100457.
Pulgar, J., Manríquez, P. H., Widdicombe, S., García-Huidobro, R., Quijón, P. A., Carter, M., Aldana, M., Quintanilla-Ahumada, D., & Duarte, C. (2023). Artificial Light at Night (ALAN) causes size-dependent effects on intertidal fish decision-making. Marine Pollution Bulletin, 193, 115190. https://doi.org/10.1016/j.marpolbul.2023.115190
Rajkhowa, R. (2014). Light pollution and impact of light pollution. International Journal of Science and Research, 3(10), 861–867. https://www.ijsr.net/archive/v3i10/T0NUMTQyMDI=.pdf
Rosenberg, Y., Doniger, T., & Levy, O. (2019). Sustainability of coral reefs are affected by ecological light pollution in the Gulf of Aqaba/Eilat. Communications Biology, 2, 289. https://doi.org/10.1038/s42003-019-0532-4
Schernhammer, E. S., Laden, F., Speizer, F. E., Willett, W. C., Hunter, D. J., Kawachi, I., & Colditz, G. A. (2001). Rotating night shifts and risk of breast cancer in women participating in the nurses' health study. Journal of the national cancer institute, 93(20), 1563-1568.
Shostak, A. (2017). Circadian clock, cell division, and cancer: from molecules to organism. International journal of molecular sciences, 18(4), 873.
Tidau, S., Smyth, T., McKee, D., Wiedenmann, J., Wilcockson, D., Ellison, A., Grimmer, A. J., Jenkins, S. R., Widdicombe, S., Queirós, A. M., Talbot, E., Wright, A., & Davies, T. W. (2021). Marine artificial light at night: An empirical and technical guide. Methods in Ecology and Evolution, 12(9), 1588-1601. https://doi.org/10.1111/2041-210X.13653
Walker, W. H., Bumgarner, J. R., Walton, J. C., Liu, J. A., Meléndez-Fernández, O. H., Nelson, R. J., & DeVries, A. C. (2020). Light pollution and cancer. International Journal of Molecular Sciences, 21(24), 9360. https://doi.org/10.3390/ijms21249360
Wang, T., Kaida, N., & Kaida, K. (2023). Effects of outdoor artificial light at night on human health and behavior: A literature review. Environmental Pollution, 323, 121321. https://doi.org/10.1016/j.envpol.2023.121321
Wang, T., Kaida, N., & Kaida, K. (2023). Effects of outdoor artificial light at night on human health and behavior: A literature review. Environmental Pollution, 323, 121321. https://doi.org/10.1016/j.envpol.2023.121321
Zhang, Y., Hu, K., Tang, Y., Feng, Q., Jiang, T., Chen, L., Chen, X., Shan, C., Han, C., Chu, W., Ma, N., Hu, H., Gao, H., & Zhang, Q. (2024). Interactive correlations between artificial light at night, health risk behaviors, and cardiovascular health among patients with diabetes: A cross-sectional study. Journal of Diabetes, 16(10), e70008. https://doi.org/10.1111/1753-0407.70008
Zhu, F., Zhang, W., Li, L., Wang, W., Liu, S., Zhao, Y., Ji, X., Yang, Y., Kang, Z., Guo, X., & Deng, F. (2024). Short-term exposure to indoor artificial light at night during sleep impairs cardiac autonomic function of young healthy adults in China. Environmental Research, 262, 119786. https://doi.org/10.1016/j.envres.2024.119786
Zielińska-Dabkowska, K. M., Xavia, K., & Bobkowska, K. (2020). Assessment of citizens’ actions against light pollution with guidelines for future initiatives. Sustainability, 12(12), 4997.
