[The effect of joint exposure to multiple air pollutants on sleep structure in patients with stable chronic obstructive pulmonary disease].

Objective: To assess the effect of joint exposure to multiple air pollutants on sleep structure in patients with stable chronic obstructive pulmonary disease (COPD), identify key air pollutants, and analyze potential influencing factors. Methods: In this panel study, 92 stable COPD patients were recruited. From March 2021 to September 2023 in Beijing, all participants completed 254 nights of sleep monitoring. The total sleep duration, light sleep duration, deep sleep duration and rapid eye movement sleep duration and their respective proportions in total sleep duration were recorded. The exposure levels of fine particulate matter (PM2.5), inhalable particulate matter (PM10), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), and carbon monoxide (CO) were estimated based on the infiltration factor method and time-activity logs of participants. To assess the lag effect of air pollutants, moving average concentrations of air pollutants from 0-1 day to 0-3 months were calculated. The linear mixed-effect model and Bayesian kernel machine regression (BKMR) model were used to assess the single and joint effects of air pollutants on sleep structure parameters in COPD patients, respectively. Results: All six types of air pollutants were associated with changes in sleep structure, manifesting as an increase in total sleep duration and light sleep proportion and a reduction in deep sleep proportion. The effects of O3 were strongest at lag 0-6 days, while other air pollutants were at lag 0-3 months. Joint exposure to multiple air pollutants exerted significant joint effects on sleep structure, and NO2 was identified as the dominant pollutant. NO2 had a posterior inclusion probability (PIP) greater than 0.5 for light sleep proportion (PIP=0.691) and deep sleep proportion (PIP=0.957). With an interquartile range (IQR) increase of 8.6 μg/m3 in NO2 at lag 0-3 months, the light sleep proportion increased by 10.5% (95%CI: 2.2%-19.4%), and the deep sleep proportion decreased by 19.5% (95%CI:-30.6%- -6.8%). Conclusion: Joint exposure to air pollutants is associated with changes in sleep structure in stable COPD patients, and NO2 may be a key pollutant.