Interaction Effect of Shift Work and Insomnia on Stroke Risk: A 19-Year Prospective Cohort Study in Korea.

OBJECTIVES:Our study aimed to investigate the association between shift work and stroke and determine whether this association varies depending on the presence of insomnia. METHODS:Utilizing the KoGES prospective cohort data, our primary exposure variables were shift work and insomnia. The occurrence of stroke was the main outcome of interest. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox regression analysis. An interaction analysis was conducted to assess the interaction of shift work and insomnia on stroke incidence. RESULTS:In the interaction analysis, shift work was significantly associated with stroke incidence only in groups with insomnia and an HR of 2.49 (1.02-6.11). CONCLUSIONS:Our study demonstrated that shift work was associated with a higher risk of stroke among the population with insomnia.