Background Long working hours are a common occupational health risk factor. The problem of long working hours and its impact on health of medical staff cannot be ignored.

Objective To investigate long working hours in medical staff of tertiary grade A hospitals in Shanghai, and evaluate the relationships of long working hours with occupational stress and fatigue accumulation.

Methods A total of 1531 medical staff in departments of emergency, internal medicine, surgery, intensive care unit (ICU), anesthesiology, and obstetrics and gynecology from 6 hospitals in 6 districts of Shanghai were selected using stratified random sampling. A structured questionnaire was used to collect information on social demographics, occupational characteristics, andbehavior and lifestyle. The Core Occupational Stress Scale (COSS) and the Self-diagnostic Questionnaire on the Accumulation of Fatigue of Laborers were used to assess occupational stress and fatigue accumulation condition. Chi-square test and Kruskal-Wallis H test were used to analyze the distributions of long working hours, occupational stress, and fatigue accumulation, log-binomial models were used to analyze the relationships of long working hours with occupational stress and fatigue accumulation, and job title stratified models were also constructed.

Results The average weekly working hours of the study subjects was (47.84±11.40) h, 65.90% of the medical staff worked more than 40 h every week. The percentages of the weekly working hours categories of 41-48 h, 49-54 h, and ≥55 h were 31.42%, 13.46%, and 21.03%, respectively. The positive rates of occupational stress and fatigue accumulation were 25.87% and 65.64% respectively, and the differences among different age, gender, job title, education, length of service, and shift system groups were statistically significant (P<0.05). The results of log-binomial regression showed that after adjusting for gender, age, monthly income, marital status, education, physical exercise, smoking, job position, length of service, and shift system, weekly working hours were an influencing factor of occupational stress and fatigue accumulation (P<0.05). Compared with weekly working hours≤40 h, the risk, PR(95%CI), of reporting occupational stress and fatigue accumulation increased to 2.595 (1.989, 3.385) and 1.578 (1.349, 1.845) times respectively for weekly working hours≥55 h (P<0.001). The results of job title stratification analysis showed that the risk of occupational stress among physicians, nurses, and medical technicians increased when weekly working hours≥55 h versus ≤40 h, and the PR (95%CI) values were 2.003 (1.383, 2.902), 1.971 (1.068, 3.636), and 2.770 (1.220, 6.288), respectively (P<0.05). The risk of fatigue accumulation was increased in physicians when weekly working hour≥55 h versus ≤40 h, with a PR (95%CI) value of 1.594 (1.208, 2.103) (P<0.001).

Conclusion Long working hours are common among medical personnel and related to the occurrence of occupational stress and fatigue accumulation.