Relationship Between Work Stress, Need For Recovery And Chronic Fatigue And Hair Cortisol Concentration

Job characteristics (particularly adverse job characteristics) give rise to work stress, thereby inducing worker’s short-term fatigue or need for recovery that is the need to recuperate from work-induced fatigue. Long-term accumulation of excessive short-term fatigue will damage physical and mental health of workers. In theory, short-term fatigue or need for recovery is an important intermediate link from the adverse job characteristics to long-term health outcomes. However, little empirical research eludates the mediation effect of need for recovery through standardized steps. On the other hand, most of previous studies focused on psychological mechanism in the accumulative process of work stress while little study concerns for physiological mechanism, such as changes in the function activity of the hypothalamic-pituitary-adrenal axis (HPA). Moreover, the related studies mostly ultilized plasma, saliva and urinary cortisol as biomarkers of work stress. However, these biomarkers showed the methodical limitations in presenting long-term accumulation of work stress, resulting in instable association of job characristics with cortisol.This study aims to explore the process from work stress induced by job characristics to need for recovey and its chronic accumulation in the perspective of psycholocal and physiological mechanisms. First, this study tests the reliability and validity of Chinese-version scale of need for recovery. Second, this study verifies the mediation role in work stress induced by various of job charateristics and long-term health outcome by using cross-section design. Third, this study examines association of job characteristics and need for recovery with hair cortisol.The result is described as follow:First, Chinese version scale of need for recovery that was translated into Chinese and re-tranlated into English was used in 554 Chinese workes in a wide series of working fields. The occupational burnout inventory, the Maslach burnout inventory and the short form-36 health survey were used as the criteria. The results revealed that the modified scale well fitted one-factor model, as indicated by confirmatory factor analysis:x2/df=2.19, RMSEA=0.047, GFI=0.97, CFI=0.96,IFI=0.98. The modified scale showed internal consistency at 0.78 and split-half reliability at 0.77. It showed the acceptable item discrimination. It showed siginificant correlations with the criteria involved in fatigue (ps＜0.001). These results indicated that the revised scale has satisfactory reliability and validity that meets the demands of psychometrics.Second, participants were 455 female nurses who were recruited from nine hospitals in Nanjing, China. Hierachical regression analysis combining with Sobel test was used to verify the need for recovery was the intermediate link from work stress induced by job characteristics (e.g., work demands, work control, effort-reward imbalance, over-commitment, surface acting and deep acting) to long-term health outcomes (e.g., emotional exhaustion and somzatization). The results revealed that work demands, effort-reward imbalance, over-commitment and surface acting were significantly and positively associated with emotional exhaustion and somzatization (ps＜0.001) and need for recovery (ps＜0.001). Deep acting was significantly and negatively associated with emotional exhaustion and somzatization (ps＜0.001) and need for recovery (p<0.001). Need for recovery were significantly and positively associated with emotional exhaustion and somzatization (ps＜0.001). The mediating effect of need for recovery was significant in the link between work demands, effort-reward imbalance, over-commitment, surface acting, deep acting and emotional exhaustion and somzatization (ps<0.001). These results implied that work stress induced by work demands, effort-reward imbalance, over-commitment and surface acting gives rise to short-term fatigue as accumulated in form of need for recovery, thereby resulting in more negative health outcomes, and that deep acting decreases short-term fatigue, thereby resulting in less negative health outcomes. The finding is the first study to verify that need for recovery is the intermediate link from work stress to long-term health outcomes.Third, participants were 43 female kindergarten teachers who were recruited from two different kinds of kindergarten. Work demands, work control, effort, reward, surface acting, deep acting and need for recovery over the last month were measured with the Chinese version scales. Hair samples with 1 cm in length were cut from their posterior vertex region to represent cortisol exposure over one month. Cortisol concentrations were measured with high performance liquid chromatography-tandem mass spectrometry. Spearman rank correlation analysis was done to examine association between questionnaire data and hair cortisol concentrations. The results showed that the ratio of effort to reward and surface acting were significantly and positively correlated with hair cortisol concentration (p<0.01, p<0.05), need for recovery was significantly and inversely correlated with HCC (p<0.01). These results suggested that the activity of the hypothalamic-pituitary-adrenal axis might increase with the effort-reward imbalance and surface acting, and decline with the accumulation of need for recovery over after working time.