Background Reducing occupational stress and thus decreasing the occurrence of sleep disorders has become an urgent need of occupational population, but relevant measures are limited and associated results are not satisfactory. Psychological capital, an important factor in positive psychology, is closely related to many mental health factors, and has positive effects on individual behavior, emotional state, work attitude, satisfaction, and performance.
Objective From the perspective of positive psychology, this paper discusses the moderating or mediating effect of psychological capital on the association between occupational stress and sleep disorders, aiming to provide a scientific basis for improving sleep quality.
Methods A questionnaire survey of psychological capital, sleep disorders, and occupational stress was conducted among 357 drilling workers who were selected by a cluster sampling method from a natural gas field in October 2018. Psychological Capital Scale was divided into four dimensions:self-efficacy, hope, resilience, and optimism. Occupational stress was investigated by Effort-Reword Imbalance (ERI) Scale, and high occupational stress level was defined as ERI index>1. Higher scores of Sleep Disorder Scale indicated severer sleep disorders. The association among occupational stress, psychological capital, and sleep disorders was analyzed by partial correlation analysis with controlling selected demographic characteristics. The moderating or mediating effects of self-efficacy, hope, resilience, and optimism on the association between occupational stress and sleep disorders were analyzed by multivariate regression analysis or Bootstrap method.
Results A total of 340 questionnaires and 327 valid questionnaires were received, with a valid rate of 96.18%. The incidence rate of highlevel occupational stress was 51.7%. The overall scores of self-efficacy, hope, resilience, optimism, and sleep disorders were 25.70±4.65, 26.08±4.55, 26.85±3.79, 24.58±3.03, and 13.40±5.86, respectively. The partial correlation analysis results showed that there was a negative correlation between occupational stress and optimism (r=-0.140, P < 0.05), and a positive correlation between occupational stress and sleep disorders (r=0.230, P < 0.01); self-efficacy, hope, resilience, and optimism were negatively correlated with sleep disorders (r=-0.130, P < 0.05; r=-0.120, P < 0.05; r=-0.210, P < 0.01; r=-0.220, P < 0.01, respectively). The multivariate regression analysis results found that self-efficacy (b=-0.140, P < 0.05), hope (b=-0.139, P < 0.05), resilience (b=-0.319, P < 0.01), and optimism (b=-0.390, P < 0.01) had negative effects on sleep disorders, but the four dimensions had no moderating effects on the association between occupational stress and sleep disorders (all P>0.05). The mediating effect test results showed that only optimism played a mediating role in the association between occupational stress and sleep disorders, and the mediating effect value was -0.292 (95% CI:-0.545--0.038); the other three variables (self-efficacy, hope, and resilience) did not.
Conclusion Psychological capital has no moderating effect on the association between occupational stress and sleep disorders in the target work group, but optimism mediates the association.
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