Background
Long working hours (LWH) and shift work are harmful to the physical and mental health of occupational groups.
Objective
To understand the status quo of LWH and shift work of migrant workers in Shanghai, and to analyze the influence of the above two factors on sleep of the population.
Methods
From July to September 2018, a cross-sectional survey using questionnaires was conducted among 3215 in-service employees at seven workplaces with more than 300 employees in six selected districts of Shanghai using multi-stage random sampling method. A total of 2976 valid questionnaires were collected, with a valid response rate of 92.6%. The questionnaires included general demographic characteristics, personal health behavior, work-related factors, weekly working hours, shift work, and sleep. Univariate analysis and logistic regression analysis were used to investigate the relationships of LWH and shift work with sleep, and an interaction item was included to evaluate potential interaction between LWH and shift work.
Result
The average age of the subjects was (30.98±9.49) years old, the male to female ratio was 1∶1.20, and 2382 workers were reported without local residency (80.0%). Among the migrant workers, the average weekly working hours was (57.23±13.14) h, the proportions of LWH (weekly working hours>40 h), extra LWH (weekly working hours>55 h), and shift work were 80.6% (1919/2382), 60.3% (1436/2382), and 25.4% (600/2366), respectively, all above were significantly higher than those of local workers. The prevalence rates of insomnia and lack of sleep among the migrant workers were 46.3% (1091/2356) and 25.4% (597/2354), respectively. The results of logistic regression model showed that after adjusting demographic characteristics such as gender, age, education level, and monthly income, as well as occupation and personal health behavior, compared with working hours ≤40 h per week, working 55-60 h per week was a risk factor for insomnia of migrant workers (OR=1.33, 95%CI: 1.02-1.72), while working >60 h per week was a risk factor for both insomnia (OR=1.37, 95%CI: 1.05-1.78) and insufficient sleep (OR=1.73, 95%CI: 1.28-2.35) of migrant workers. Shift work was only associated with insomnia (OR=1.37, 95%CI: 1.11-1.69). Meanwhile, working hours>60 h per week and shift work had an interaction effect on insomnia of migrant workers (OR=2.35, 95%CI: 1.20-4.60).
Conclusion
LWH and shift work are prominent among migrant workers, and there is an interaction between LWH and shift work with insomnia.
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