Sleep app tracks link between air pollution and a bad night’s sleep Sarah Collins Tue, 09/15/2026 - 10:00 Researchers from the University of Cambridge, Tsinghua University and the sleep technology company Sleep Cycle analysed coughing sounds from 32 cities in 12 countries over 500 days, and found that higher daily air pollution levels were strongly linked to nighttime coughing levels, even where local pollution levels were below the World Health Organization’s recommended daily exposure limit. The researchers used cough sounds passively recorded by the mobile app via the phone’s microphone. Cough sounds were counted on individual devices and pooled by city to build an unprecedented dataset o...