Cumulative night-shift burden and sleep quality among healthcare Workers: Dose–response evidence from an analytical cross-sectional study

Abstract Background Shift work is common among healthcare workers; however, the effects of cumulative night-shift exposure on sleep dimensions and the pathways linking shift work with sleep quality remain insufficiently understood. This study examined the association between shift-work characteristics and sleep quality, emphasizing cumulative night-shift burden. Methods An analytical cross-sectional study was conducted among 411 healthcare workers selected using a two-stage sampling strategy. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), and poor sleep quality was defined as a global PSQI score > 5. Multivariable logistic regression identified predictors of poor sleep quality. Dose-response relationships between monthly night-shift frequency and poor sleep quality were evaluated using quartile analyses and restricted cubic spline modelling. Individual PSQI component scores identified sleep domains most affected by shift work, and exploratory path analysis investigated pathways linking shift-work exposure with sleep quality. Results Poor sleep quality was prevalent. Cumulative night-shift exposure emerged as the strongest predictor of poor sleep quality. Increasing monthly night-shift frequency demonstrated a dose-response relationship, with higher odds of poor sleep quality. Night-shift burden was associated with shorter sleep duration, poorer sleep efficiency, increased sleep disturbances, and daytime dysfunction. Exploratory path analysis supported a pathway in which cumulative night-shift exposure was associated with prolonged sleep latency. Conclusions Cumulative night-shift burden is an occupational determinant of poor sleep quality. These findings demonstrate dose-dependent effects of night-shift exposure and identify sleep domains most affected. Reducing night-shift exposure and incorporating sleep health into occupational health programmers may improve well-being, workforce sustainability, and patient safety.