Extreme Heat Exposure and COPD Mortality: Insights from Sleep Time

Extreme heat, a growing consequence of climate change, can disrupt sleep, potentially increasing the risk of life-threatening exacerbations in patients with chronic obstructive pulmonary disease (COPD). However, direct evidence linking sleep-time heat to COPD mortality is limited. We therefore conducted a time-stratified case-crossover study combining conditional logistic regression and a distributed lag nonlinear model to examine the association. Cumulative excess sleep-time apparent temperature (eSAT) was used to represent the intensity of extreme heat during sleep. Daily COPD mortality data from 2015 to 2022 were collected from Jiangsu Province, China. We also estimated the mortality burden attributable to eSAT. During the study period, a total of 130,252 COPD deaths were included in the analyses. A monotonic, nonlinear increase in mortality from COPD, acute exacerbation of COPD (AECOPD), and chronic bronchitis was observed with increasing eSAT. The effects were more prominent among females, older adults, widowed individuals, farmers, and individuals living in the city with lower ownership of air conditioners. Exposure to eSAT was responsible for 3.37%, 3.07%, and 4.59% of deaths from COPD, AECOPD, and chronic bronchitis, respectively. This study demonstrates the impact of extreme heat during sleep on COPD mortality and underscores the need for targeted interventions to protect respiratory health.