Longitudinal trajectories and risk factors of insomnia symptoms among Chinese bus drivers

Objectives: This study investigated the three-year prevalence and longitudinal trajectories of insomnia symptoms among bus drivers and examined key sociodemographic-health-related factors and psychosocial predictors, with the aim of informing targeted preventive strategies. Methods: A total of 11,576 bus drivers from 22 companies in Guangdong participated in three online surveys at T1 (August-December 2019), T2 (October-December 2021), and T3 (October-December 2023). The surveys assessed demographics, insomnia symptoms, and psychosocial factors. Two-stage multivariate logistic regression models were employed to examine risk factors associated with adverse trajectories. Results: Prevalence of insomnia symptoms declined steadily from 12.5% at T1 to 7.8% at T3. Five distinct trajectories were identified: resistance (78.5%), chronic dysfunction (1.9%), delayed dysfunction (4.7%), recovery (9.4%), and relapsing/remitting (5.5%). Sociodemographic and psychosocial distress factors (e.g., age, lower financial status, job burnout, family dysfunction) significantly increased the risk of general insomnia and adverse trajectory membership. Crucially, a history of severe physical illness was a strong determinant of chronic risk, while exercising for 30 min daily was significantly associated with a higher likelihood of recovery. Conclusion: Our study offers insights into the longitudinal trajectories of insomnia symptoms and their associated risk factors among Chinese bus drivers. These findings carry important implications for designing trajectory-specific occupational health interventions and refining public transportation management strategies.