Artificial light at night extends allergy seasons by up to two weeks, new study finds

While light pollution has long been recognized as a threat to migrating birds and sea turtles, groundbreaking new research reveals it may also be making allergy sufferers miserable for longer periods each year. A comprehensive study spanning 2012 to 2023 found that artificial light at night (ALAN) causes plants to produce pollen for extended periods, potentially adding one to two weeks to allergy seasons.

Researchers from Vanderbilt University analyzed pollen count data alongside satellite observations of nighttime lighting across the northeastern United States, including major urban centers like New York, Boston, and Philadelphia. By using advanced modeling to control for variables such as temperature and precipitation, they were able to isolate the specific effects of artificial lighting on plant behavior. The results showed that areas with higher exposure to nighttime artificial light consistently had elevated pollen levels and longer pollen seasons.

“This research is clearly nothing to sneeze at,” said Andrew Richardson, an ecologist with Northern Arizona University who was not involved in the study, emphasizing that seasonal allergies already cost billions in healthcare expenses while significantly impacting quality of life for sensitive individuals. The mechanism behind this phenomenon lies in how artificial light disrupts plants’ natural circadian rhythms. While nighttime lighting cannot replace sunlight for photosynthesis, it confuses plants’ internal clocks, affecting their flowering and pollen production cycles.

This discovery adds another layer of concern to the growing impact of light pollution on both human health and environmental systems, particularly as climate change is already extending allergy seasons through warming temperatures.