Artificial Light At Night: State Of The Science 2026

Image credit: NASA's Goddard Space Flight Center  
1117 words / 4 1/2-minute read

Light pollution is now pervasive in our world. Experts and governments more often recognize it as a form of environmental pollution. The tide of public awareness continues to rise. Both light pollution and dark skies are topics of media stories, television shows and podcast episodes. One finds in them clear messages: artificial light at night (ALAN) threatens the natural world.

Yet stories and presentations tend to consider the matter at only a shallow depth. Detailed 'deep dives' are few. It can be difficult to understand the topic very well by only consuming those media. At the same time, access to accurate and reliable information is more important than ever. And both decision makers and the public need that information now more than ever.

This month we look at the latest global view of light pollution and ALAN science. We highlight some key research findings published in 2025 and consider the most important unanswered questions. 

An annual survey of the scientific landscape

In 2022 DarkSky International released the first report called "Artificial Light at Night: State of the Science". It aimed to present the best of what we know about light pollution in a way that the public can understand. It surveyed a landscape of almost 4,000 published papers and studies in the ALAN Research Literature Database.

The text distilled decades of scientific research into a few pages of understandable language. Hundreds of source citations supported its conclusions. The organization published the report under a Creative Commons license to enable its re-use.

Each year DarkSky International updates the report with the latest results from scientific studies of ALAN. It culls through over 500 new papers published on average each year. In these sources it looks for the common threads tying new results to a growing body of knowledge. The search sometimes turns up unexpected results worth highlighting. It also updates existing knowledge with new source citations.
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The annual update ensures that DarkSky International and its dark-sky advocates stay current on new scientific developments. The report is a valuable resource for the advocates in communicating with both the public and policy makers around the world. It also adds credibility to their advocacy.

Light pollution science advances of 2025

The report for 2026, released last month, finds light pollution a bigger social and environmental concern than ever. Studies published in 2025 both build on previous knowledge and reveal some surprises. Here we highlight some notable examples.

Our understanding how ALAN lights up the night sky is now very sophisticated. Miro Kocifaj (Slovak Academy of Sciences and Comenius University, Slovakia) and co-workers published the first model of night sky brightness that accounts for various cloud types and coverage. Their model "can be used to explain observational data collected by light pollution monitoring networks, particularly at sites where the combination of amplifying and darkening effects of clouds generates ambiguous brightness outcomes."

Light pollution has distinct synergies with other pollutants. Yongbin Wang (Xinxiang Medical University, China) led a team that explored links between ALAN and air pollution. They found that the combined effects elevated the risks of high blood pressure, heart and liver disease. They conclude that "policy interventions targeting light pollution reduction and air quality improvement are urgently needed to mitigate environmental health risks."

ALAN is causing ecological changes with profound effects, especially in cities. Lvlv Wang (Wuhan University, China) and coauthors examined the competing effects of light pollution and urban heating on plants. Plants exposed to ALAN experienced a longer growing season compared to those affected only by warm nighttime temperatures. They argued that "ALAN is a critical driver of vegetation dynamics in cities, one we should consider during urban management and development."

ALAN may affect entire ecosystems. It was long believed that light pollution had local-to-regional effects on segments of natural systems. But a Nature Climate Change paper by Alice Johnston, Jiyoung Kim and Jim Harris (Cranfield University, UK) found something very different. ALAN seems to influence the cycle that governs the exchange of carbon between the living and non-biological worlds. This has serious implications for a planet that continues to rapidly warm.

Public acceptance of outdoor lighting policies finds its roots in perceptions of darkness. Two papers provided new social science data assessing the public's attitudes toward nighttime darkness. Richard Jedon (Eindhoven University of Technology, Netherlands) and colleagues showed that increased anxiety experienced by pedestrians in dark areas of cities "made participants less willing to allow lower levels of streetlighting".

Meanwhile, Solène Guenat and Nicole Bauer (Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Switzerland) demonstrated that study participants "who lived or grew up in high-sky brightness regions were more likely to feel unsafe". They also have a more favorable view of ALAN as having social benefits, decreasing its recognition as a pollutant.

Space light pollution continues to rise. As the orbital space around the Earth fills with tens of thousands of new satellites, researchers expect the night sky to get brighter. Rockets and satellites shedding debris in space are especially concerning. In a study of low-Earth orbit space, Miro Kocifaj , František Kundracik and Stefan Wallner reported projections "an increase in night sky background brightness of 5 to 11 per cent above natural levels" by 2035. In some parts of the world, this increase could exceed the amount of ground-based light pollution.

Where research can go from here

"Artificial Light at Night: State of the Science 2026" closes with a summary of the most pressing research questions of our time. New additions this year include:

• Which lighting policy interventions are most effective in reducing skyglow? Are lighting policies effective? If not, why?
• Are organisms evolving responses to light pollution?
• Can any reliable ‘dose-response’ relationship be defined between outdoor ALAN and safety and/or security?
• How are some measures of ALAN such as skyglow specifically related to a suite of undesired outcomes (e.g., adverse ecological, health, or astronomical outcomes)?
• Is it possible to define an overall efficiency metric for outdoor lighting that considers both its energy efficiency and unintended, negative environmental/social consequences?
• How will novel uses of outer space, such as the deployment of orbital sunlight reflectors, change nighttime conditions on Earth?

The expanding body of artificial light at night (ALAN) research published in 2025 represents a turning point. Our understanding of the profound ecological, physiological, and cultural impacts of light pollution is deepening. We recognize that the gap between scientific consensus and public policy must close.

The task of science now is to address the remaining unanswered questions. Its findings can help translate data into actionable local, national and international protections. In turn, we can begin to reverse the tide of global skyglow and safeguard the nocturnal commons for generations to come.