Elsevier

Social Science & Medicine

Volume 59, Issue 8, October 2004, Pages 1719-1730
Social Science & Medicine

Job stress, social support, and prevalence of insomnia in a population of Japanese daytime workers

https://doi.org/10.1016/j.socscimed.2004.02.002Get rights and content

Abstract

To clarify the relationship between perceived job stress, social support and prevalence of insomnia in Japanese daytime workers, 1161 male white-collar employees of an electric equipment manufacturing company (age, 23–60 years, mean age of 37.0) were surveyed by means of a mailed questionnaire. Perceived job stress was evaluated with the Japanese version of the generic NIOSH job stress questionnaire. Insomnia was diagnosed if workers had at least 1 of 3 types of symptoms on an almost nightly basis. The symptoms were (1) taking more than 30 min to fall asleep (Difficulty Initiating Sleep, DIS), (2) difficulty in maintaining sleep (DMS), or (3) early morning awakening (EMA). The overall prevalence of insomnia was 23.6% and the prevalences of the three subtypes were 11.3% for DIS, 14.2% for DMS, and 1.9% for EMA. Workers with high intragroup conflict (OR 1.6), high job dissatisfaction (OR 1.5), and high symptoms of depression (OR 2.0) (CES-D>16) had a significantly increased risk for insomnia after adjusting for multiple confounding factors. Low employment opportunities, physical environment and low coworker support also were weakly associated with risk for insomnia among workers. Furthermore, high depressive symptoms significantly increased the risk of DIS (OR 2.4). Therefore in white-collar male daytime workers, psychological job stress factors such as interpersonal conflicts with fellow employees, job satisfaction, and social support were independently associated with a modestly increased risk of insomnia that included three different subtypes that were considered to be defining for the disorder.

Introduction

Insomnia has a prevalence of 16–30% in a daytime working population, making it one of the most commonly reported health problems caused by sleep disorders (Lavie, 1981; Jacquinet-Salord, Lang, Fouriaud, Nicoulet, & Bingham, 1993; Kuppermann et al., 1995; Tachibana et al., 1996; Harma, Tenkanen, Sjoblom, Alikoski, & Heinsalmi, 1998; Nakata et al., 2000). Insomnia causes both occupational and social problems. Consequences of insomnia include reduced productivity, increases in accidents at work, absenteeism, use of medical care services, and interpersonal difficulties (Lavie, Kremerman, & Wiel, 1982; Vollrath, Wicki, & Angst, 1989; Jacquinet-Salord et al., 1993; Stoller, 1994). The risk factors for insomnia that have been examined in epidemiologic studies include age, gender, socioeconomic status, health status, quality of life, environmental factors, shift work, and psychological stress (Klink, Quan, Kaltenborn, & Lebowitz, 1992; Katz & McHorney, 1998; Harma et al., 1998; Ribet & Derriennic, 1999; Kim, Uchiyama, Okawa, Liu, & Ogihara, 2000). Shift work and job stress are suspected to be the two major occupational risk factors. Detailed epidemiological studies have analyzed the effects of shift work on sleep. A consistent finding is that shift work is associated with insomnia, as well as other sleep problems such as sleep deprivation, excessive daytime sleepiness, increased use of sleeping pills, and chronic fatigue (Costa, 1997; Harma et al., 1998; Kalimo, Tenkanen, Harma, Poppius, & Heinsalmi, 2000). The mechanisms that cause the problems among shift workers are likely to be the result of psychological, social, and biological factors that interact in a complex way. However desynchronization of the circadian rhythms induced by an irregular sleep-wake schedule is thought to be the major cause (Akerstedt, 1990).

In sharp contrast to the extensive research on the sleep problems of shift workers, there have been only a few studies that focused on the association between job stress and sleep. Studies in both the US and some European countries have documented that parameters of job stress, such as high job demands (Cahill & Landsbergis, 1996; Kalimo et al., 2000; Pelfrene et al., 2002), low job control (Kalimo et al., 2000; Pelfrene et al., 2002), high job strain that is defined by a combination of high job demands and low job control (Theroell et al., 1988; Cahill & Landsbergis, 1996), low social support at workplace (Landsbergis, 1988; Pelfrene et al., 2002), and dissatisfaction with work (Kuppermann et al., 1995) are associated with an increase in sleep problems. A bad atmosphere at work and a low level of interest in the job (Jacquinet-Salord et al., 1993), as well as overall mental workload, a too heavy work day, unfinished work, and working before bedtime (Urponen, Vuori, Hasan, & Partinen, 1988) have also been proposed as factors that disturb sleep.

The association of job stress with sleep disorders has not been well studied in the Japanese working population. Kageyama et al. (1998) compared job stress scores between poor and good sleepers in 223 white-collar male workers. The poor sleepers had significantly higher scores in job difficulty and lower scores in both job achievement and support by colleagues when compared to good sleepers. Over-involvement in a job was also a risk factor for insomnia in 271 male industrial workers (Tachibana et al., 1996). In our previous report, we found an inverse relationship between social support from a coworker or supervisor and sleep complaints in 325 young female daytime employees (Nakata et al., 2001a). In addition, 530 rotating shift workers with low social support at work had a significantly higher prevalence (55.9%) of insomnia than the insomnia prevalence of 35.3% in workers with high support levels (Nakata et al., 2001b). A recent study (Doi, Minowa, & Tango, 2003) reported that workers who were dissatisfied with their job had a higher prevalence of insomnia than satisfied workers.

Despite the findings by some investigators that point to a relationship between job stress and sleep problems, some studies find no relationships. Associations between sleep with job control (Landsbergis, 1988; Kageyama et al., 1998; Nakata et al. (2001a), Nakata et al. (2001b); Akerstedt et al., 2002), job quantity or demands (Kageyama et al., 1998; Nakata et al., 2001b; Akerstedt et al., 2002), work overload, and social support at the workplace (Tachibana et al., 1996; Akerstedt et al., 2002) were not significant. Inconsistency in the results might be for the following reasons. First, most studies examined job stress factors by invalid or unreliable measures (Urponen et al., 1988; Jacquinet-Salord et al., 1993; Kuppermann et al., 1995; Tachibana et al., 1996; Kageyama et al., 1998; Ribet & Derriennic, 1999). Second, even a well-established job stress measure like the Job Content Questionnaire (JCQ) (Karasek & Theorell, 1990) covers only job control, job demands, or social support, which are limited aspects of job stress in the workplace (Landsbergis, 1988; Theroell et al., 1988; Cahill & Landsbergis, 1996; Kalimo et al., 2000; Akerstedt et al., 2002; Nakata et al., 2001b). Third, confounding factors such as sociodemographics and lifestyle, physical and psychological health status, as well as shift work that might profoundly have impact on results were not always taken into account (Theorell et al., 1988; Urponen et al., 1988; Landsbergis, 1988; Klink et al., 1992; Jacquinet-Salord et al., 1993; Kuppermann et al., 1995; Tachibana et al., 1996; Kageyama et al., 1998; Katz & McHorney, 1998). Fourth, the relatively small sample sizes, ranging from 71 to 325 (Theroell et al., 1988; Tachibana et al., 1996; Kageyama et al., 1998; Nakata et al., 2001a), make conclusions less definitive. Finally, the unique work organization of Japan, as compared to other industrialized countries, may be a cultural situation that leads to a different association between job stress and sleep.

The effects of different sources of job stress on insomnia in the working population have not yet been systematically investigated. To clarify the association of broad aspects of job stress with the prevalence of insomnia in male white-collar daytime workers, we have conducted a cross-sectional survey in an electric equipment manufacturing company in Japan. Perceived job stress was evaluated by the Japanese version of the National Institute for Occupational Safety and Health (NIOSH) Generic Job Stress Questionnaire (GJSQ), which is a well-established means of measurement (Hurrell & McLaney, 1988; Haratani, Kawakami, & Araki, 1993; Haratani et al., 1996). Length of time to fall asleep, frequency of awakening during sleep and early morning awakening, as used in our previous studies, were assessed as measures of subjective sleep habits (Nakata et al. (2000), Nakata et al. (2001a), Nakata et al. (2001b)). The conceptual model shown in Fig. 1 (solid arrows) was tested in this study.

Section snippets

Subjects

A total of 2625 full-time workers in an electric equipment manufacturing company in Japan were participants in the study. The ages of participants ranged from 18 to 60 years. The workers were surveyed in April 1997 by soliciting responses to a mailed questionnaire. The survey questionnaire was used to gather information concerning sociodemographics, job stress, sleep habits, current type of job, work schedule, life style factors, and physical status (Table 1). A total of 2420 (92.2%) workers

Results

The results are presented to show first the association of all the job stress scales with insomnia (Table 5). The second set of results show the statistically significant relationships between job stress scales and DIS, DMS, and EMA (Table 6, Table 7, Table 8).

Discussion

This study shows that the overall prevalence of insomnia in the study population of Japanese white-collar male workers was 23.6%, which is comparable to the findings in previous studies (15.8–29.6%) (Lavie, 1981; Jacquinet-Salord et al., 1993; Kuppermann et al., 1995; Tachibana et al., 1996). In addition, the three subtypes of insomnia were independently associated with job stress factors, such as interpersonal conflicts at work, job satisfaction, and depressive symptoms after adjustment for a

Acknowledgements

We are grateful to Professor Dr. Ichiro Kawachi, Department of Health and Social Behavior, Harvard School of Public Health for his invaluable suggestions. Thanks are also due to Professor Dr. Hiroyuki Shimizu, Department of Public Health, Gifu University School of Medicine. The study was performed through Special Coordination Funds for Promoting Science and Technology from the Ministry of Education, Culture, Sports, Science and Technology of the Japanese Government.

References (46)

  • G. Costa

    The problemShiftwork

    Chronobiology International

    (1997)
  • Y. Doi et al.

    Impact and correlates of poor sleep quality in Japanese white-collar employees

    Sleep

    (2003)
  • B. Fruhstorfer et al.

    Daytime noise and subsequent night sleep in man

    Euopeanr Journal of Applied Physiology and Occupational Physiology

    (1984)
  • T. Haratani et al.

    Reliability and validity of the Japanese version of NIOSH generic job stress questionnaire

    Japanese Journal of Industrial Health

    (1993)
  • Haratani, T., Kawakami, N., Araki, S., Hurrell Jr., J.J., Sauter, S.L., Swanson, NG. (1996). Psychometric properties...
  • M. Harma et al.

    Combined effects of shift work and life-style on the prevalence of insomnia, sleep deprivation and daytime sleepiness

    Scandinavian Journal of Work Environment and Health

    (1998)
  • J.J. Hurrell et al.

    Exposure to job stress—a new psychometric instrument

    Scandinavian Journal of Work Environment and Health

    (1988)
  • M.C. Jacquinet-Salord et al.

    Sleeping tablet consumption, self reported quality of sleep, and working conditions

    Journal of Epidemiology and Community Health

    (1993)
  • Japanese Ministry of Public Management, Home Affairs, Posts and Telecommunications, Statistics Bureau and Statistics...
  • T. Kageyama et al.

    Self-reported sleep quality, job stress, and daytime autonomic activities assessed in terms of short-term heart rate variability among male white-collar workers

    Industrial Health

    (1998)
  • R. Kalimo et al.

    Job stress and sleep disordersFindings from the Helsinki heart study

    Stress Medicine

    (2000)
  • R. Karasek et al.

    Healthy work

    (1990)
  • D.A. Katz et al.

    Clinical correlates of insomnia in patients with chronic illness

    Archives of Internal Medicine

    (1998)
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