Recent studies have yielded conflicting results regarding the health effects of sunshine, with some suggesting benefits and others indicating adverse effects. This study investigates the relationship between sunshine duration and cause-specific mortality in Beijing, China, from 2008 to 2011. We assessed the non-linear, lagged effects of sunshine duration on mortality risk using a distributed lag non-linear model (DLNM) combined with quasi-Poisson regression. We determined the minimum mortality sunshine duration based on the overall cumulative relationship between sunshine duration and mortality, and calculated the attributable fractions of mortality for both long and short sunshine durations. The study encompassed 289,743 non-external deaths, 145,477 cardiovascular deaths, and 29,779 respiratory deaths in Beijing. A J-shaped association was observed between sunshine duration and all-cause, cardiovascular, and respiratory mortality. The estimated attributable fractions of mortality due to non-optimum sunshine duration were 7.21% (95% empirical confidence interval eCI: 3.16, 11.01%), 8.57% (95% eCI: 2.04, 14.69%), 14.03% (95% eCI: 5.36, 21.42%) for all-cause, cardiovascular, and respiratory mortality, respectively, with a larger estimated burden attributed to sunshine duration above the MMSD than below it. No significant differences were found across gender or age subgroups. Non-optimum sunshine duration was associated with all-cause, cardiovascular, and respiratory mortality in Beijing. These findings may have implications for understanding the health effects of sunshine duration at the population level. • Limit evidence on the association between sunshine duration and mortality. • The effect of sunshine duration on mortality was non-linear, with J-shaped curves. • Non-optimum sunshine duration was associated with the attributable mortality burden.
Hu et al. (2026) studied this question.