Earth’s nights grew roughly 16% brighter between 2014 and 2022, at a rate of about 2% per year, according to a study published April 9, 2026, in the journal Nature, led by researchers from the University of Connecticut in collaboration with Christopher Kyba of Ruhr-University Bochum and the GFZ Helmholtz Centre for Geosciences, using the most detailed nighttime satellite analysis ever conducted at full global resolution.
The result, however, conceals a sharper story: where light at night increased across the planet, total emissions rose by 34%, but that gain was partly offset by an 18% reduction in areas that darkened, producing the 16% net figure; the global average hides regional patterns that move in opposite directions for very different reasons, from urban growth policies in Asia to energy conservation measures in western Europe to war-related blackouts in eastern Europe.
What eight years of satellite data reveal
The study draws on data from the VIIRS DNB (Visible Infrared Imaging Radiometer Suite Day/Night Band), a sensor aboard the Suomi NPP, NOAA-20, and NOAA-21 satellites operated by NOAA and NASA, which scan the planet each night between 1:00 a.m. and 4:00 a.m. local time at a pixel resolution of 0.5 square kilometers; critically, previous global analyses worked with monthly or annual averages, smoothing out short-term and localized shifts, so this study represents the first time a team applied full-resolution nightly data to map how light at night changes across the entire globe.
China and India drove the most consistent brightening through rapid urban construction and infrastructure expansion, while Europe as a whole darkened by 4% over the eight-year period, led by France, where nighttime light emissions fell 33% as cities adopted policies turning off streetlights after midnight to cut electricity costs and reduce light pollution; Germany recorded an almost flat net result, with emissions rising 8.9% in brightening regions and falling 9.2% in dimming ones.
Global light pollution is increasing, but in large areas of the planet, such as Europe, it is decreasing due to technological maturity and environmental awareness https://t.co/g03CHGdgXI
— EL PAÍS América (@elpais_america) April 9, 2026
Why light at night is more than an astronomy problem
Chronic exposure to artificial light at night (ALAN) suppresses the production of melatonin, the hormone that governs the human sleep-wake cycle and acts as an internal signal to organs and tissues across the body that night has arrived; when artificial light delays or blocks that signal, the resulting misalignment of the body’s internal clock links, in peer-reviewed epidemiological research (studies that track disease patterns in large populations), to higher risks of cardiovascular disease, metabolic syndrome, and certain cancers.
In wildlife, the effects run parallel: ALAN disrupts migratory routes in birds that navigate by stars, alters the reproductive cycles of insects and amphibians, and shifts predator-prey behavior by making nocturnal (night-active) animals easier to detect or more inclined to change their activity patterns, compressing the ecological role that natural darkness plays in maintaining species diversity.
The research team also flagged a technical complication: the satellite measures light in the visible spectrum, but LED lamps, now standard across most modernizing cities, emit a spectrum shifted toward blue-wavelength light that VIIRS detects with lower efficiency; cities that switch from older sodium lamps to LEDs may appear to dim in the satellite data while actually emitting the same amount or more light at biologically relevant wavelengths for the human eye.
Kyba is currently leading the development of a dedicated night-monitoring satellite under the European Space Agency’s Earth Explorer 13 mission, a project that would detect far fainter light sources and offer significantly higher resolution than existing NOAA and NASA hardware; as of April 2026, the United States and China each operate multiple satellites capable of observing nighttime light, and Europe has none designed specifically for that purpose, a gap the mission aims to close before the next decade of data on light at night goes unrecorded at the resolution the science now requires.