Elsevier

Sleep Medicine

Volume 6, Issue 4, July 2005, Pages 353-358
Sleep Medicine

Original article
Association between psychosocial job characteristics and insomnia: an investigation using two relevant job stress models—the demand-control-support (DCS) model and the effort-reward imbalance (ERI) model

https://doi.org/10.1016/j.sleep.2004.12.008Get rights and content

Abstract

Background and purpose

The details of risky psychosocial job characteristics related to insomnia are unclear, although potential relationships between the two have been suggested. The study objective was to clarify these relationships by using the demand-control-support (DCS) model and the effort-reward imbalance (ERI) model.

Patients and methods

A cross-sectional questionnaire survey was conducted with 1081 middle-aged (39 years and older) workers in a corporate group of electric products in Osaka, Japan. The study variables included insomnia symptoms (non-refreshing sleep, difficulty falling asleep, frequent sleep disruption, and early morning arousal) and psychosocial job characteristics which were evaluated using the DCS and ERI models, gender, age, disease, sleep-related factors, occupational status, and health practices.

Results

ERI [odds ratio (95% confidence interval): 2.27 (1.43, 3.60)], overcommitment [1.86 (1.40, 2.47)], and high job strain [1.55 (1.12, 2.15)] were independently associated with insomnia. The odds ratio of insomnia for individuals with high job strain was increased by adding ERI or overcommitment.

Conclusions

The ERI and DCS models describe the adverse psychosocial job characteristics related to insomnia. Simultaneously employing these two models is more useful than employing a single model to identify workers at risk of insomnia. The conceptual framework derived from the job stress models assists in defining preventive measures for insomnia in workers.

Introduction

Insomnia is a common health complaint. Worldwide, 16–21% of the population experiences insomnia symptoms at least 3 nights per week, more often, or always [1]. The average prevalence of dissatisfaction with sleep quality and quantity is 8–18% [1]. Insomnia often causes daytime sleepiness and fatigue, decreased physical and mental performance, and an increased number of accidents in daily life and at the workplace.

Stress at the worksite could affect workers' sleep. The relationships between psychosocial job characteristics and insomnia have been examined. The results, however, vary [2], [3], [4], [5], [6], [7], [8], [9]. With a few exceptions [4], [8], one disadvantage of previous studies lies in the fact that each study has used its own distinct definition to assess the psychosocial job characteristics, which hinders the integration of previous findings toward establishing which job stressors should be removed in order to prevent workers from developing insomnia.

Occupational psychosocial researchers are currently using theory-based conceptual job stress models, such as the demand-control-support (DCS) model [10], [11], [12] and the effort-reward imbalance (ERI) model [13]. These models categorize job stressors that are harmful to health and offer a consistent framework for the improvement of working conditions. The DCS model focuses exclusively on the job task profile, whereas the ERI model combines situational and personal conditions at worksites. Prospective cohort studies revealed that high job strain (high psychological job demand combined with low decision latitude) and ERI (high effort at work along with low financial and positional return) were risky job stressors related to the incidence and mortality of coronary heart disease [14], [15], [16]. Moreover, the combination of these two measures of the models resulted in the creation of a more efficient predictor of other health outcomes, such as coronary heart disease [17], mental distress [18], poor well-being [19], and poor self-reported health status [20], than the use of only one of the model components. Based on these findings, it is speculated that the two models are complementary to each other in evaluating the multidimensional features of job stressors. Moreover, a combination of the two models could improve the prediction of health outcomes by providing further explanation for harmful psychosocial job characteristics than the separate use of each model. However, with regard to insomnia, only a few studies [4], [8] adopted the DCS model and no study has employed the ERI model to elucidate the worksite stressors.

The objective of this cross-sectional study was to examine whether the ERI model, the DCS model, and their combination can be used to explain the risky psychosocial job characteristics related to insomnia. Middle-aged workers were chosen as subjects in this study. As they age, these workers experience insomnia symptoms with an increasing frequency [21].

Section snippets

Subjects

All middle-aged (39 years and older) Japanese workers (n=1786) in 8 companies of a corporate group of electric products in Osaka prefecture, Japan, were considered to be eligible participants. A total of 1732 workers (97.0%) provided written informed consent to participate in this study and received the questionnaire. The self-reported questionnaires were returned by 1699 workers (95.1%). A total of 618 respondents (34.6%) were excluded because of one or more missing responses. The remaining

The summary of the subjects

The subjects were male-dominant [n of male=983 (90.9%)]. The median of age was 44 (range, 39–66). The numbers (%) of the subjects aged 39, 40–49, 50–59, and 60 and above were 68 (6.3%), 747 (69.1%), 258 (23.9%), and 8 (0.7%), respectively. Reports of previously treated diseases and current illness were obtained from 481 (44.5%) and 269 (24.9%) subjects, respectively. A total of 800 (74.0%) workers were classified as white-collar. The median of overtime work hours worked during the previous

Discussion

The findings reveal that the two theory-based conceptual job stress models, the ERI and DCS models, describe the adverse psychosocial job characteristics related to insomnia. ERI, overcommitment, and high job strain are independently associated with insomnia. The associations of ERI, overcommitment, and high job strain with insomnia remain significant even after controlling for possible confounding factors. Psychosocial job characteristics deserve considerable attention and should be studied in

Conclusions

The ERI and DCS models describe adverse psychosocial job characteristics related to insomnia. The risk of insomnia is well predicted by simultaneously employing these two job stress measurements. The conceptual framework derived from these job stress models helps to define preventive measures for insomnia in workers.

Acknowledgements

The authors wish to thank Mr Mitsuhiro Matsuda, Ms Hiromi Yamamoto, Ms Yuka Kobayashi, and Ms Kayo Yakushige for their kind support and help with the data collection.

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