Objective To examine the association between night-shift work and sleep disorders among automobile manufacturing workers, identify potential high-risk groups, and provide orientation for the prevention and control of workers' sleep disorders.

Methods From July to December 2024, a cluster sampling method was used to recruit 1 455 employees in an automobile engine manufacturing enterprise of Guangzhou. A unified self-administered questionnaire combined with the Pittsburgh Sleep Quality Index (PSQI) was used for data collection. Logistic regression models and restricted cubic spline analyses were applied to assess the relationship between night-shift work and sleep disorders.

Results A total of 1 355 valid questionnaires were collected, with a valid response rate of 93.1%. The study population was predominantly male (94.10%), and 470 participants (34.68%) had sleep disorders. Three independent multivariable logistic regression models showed that: (1) compared with standard daytime workers, employees working on two-shift and three-shift systems had a higher risk of sleep disorders, with ORs of 2.01 and 2.79, respectively (both P < 0.05); (2) compared with non-shift workers, those with >15 years of shift-work experience had an increased risk of sleep disorders (OR = 1.87, P < 0.05); (3) workers who had night shifts in the past month had a higher risk of sleep disorders (OR = 1.39, P < 0.05); (4) across all three models, heavy physical labor was consistently associated with increased risk (OR = 2.86, 3.00, and 2.92; all P < 0.05), higher BRI values were associated with increased risk (OR = 1.15, 1.15, and 1.17; all P < 0.05), while healthier dietary patterns were associated with reduced risk (OR = 0.39 to 0.70; all P < 0.05). Restricted cubic spline analysis revealed a nonlinear dose-response relationship between years of shift work and sleep disorders, with a steep increase in risk observed after 12.0 years of shift-work experience (P < 0.05).

Conclusions Night-shift work increased the risk of sleep disorders, and shift-work duration showed a nonlinear dose-response relationship with sleep disorder risk. Workers with more than 12 years of shift-work experience should be prioritized as a key population for targeted prevention and control strategies.