Effects of perceived job stress on depressive symptoms in blue-collar workers of an electrical factory in Japan.

This three-year prospective study on the effects of job stress on depressive symptoms over time was conducted among male blue-collar workers in an electrical factory in Japan. Data were collected at yearly intervals by means of postal questionnaires. Initially ten job stress variables, five major covariates, and depressive symptoms (Zung Self-Rating Depression Scale) were measured. In the yearly examinations, depressive symptoms were measured for a total of 468 respondents. The results indicated that job unsuitability was a significant predictor of depressive symptoms in the second and third year, after control for the initial covariates and depressive symptoms. Lack of control over workplace and poor human relations at the workplace were significantly associated with depressive symptoms after one and two years, respectively. Job unsuitability and poor human relations at the workplace seem to be risk factors for long-lasting depressive symptoms in Japanese blue-collar workers.

Epidemiology of job stress and health in Japan: review of current evidence and future direction.

With the increasing concern about job stress, there is a growing body of literature addressing psychosocial job stress and its adverse effects on health in Japan. This paper reviews research findings over the past 15 years concerning the assessment of job stress, the relationship of job stress to mental and physical health, and the effects of worksite stress reduction activities in Japan. Although studies were conducted in the past using ad-hoc job stress questionnaires, well-established job stressor scales have since been translated into Japanese, their psychometric properties tested and these scales extensively used in recent epidemiologic studies. While the impact of overtime and quantitative job overload on mental health seems moderate, job control, skill use and worksite support, as well as qualitative job demands, had greater effects on psychological distress and drinking problems in cross-sectional and prospective studies. These job stressors also indicated a strong association with psychiatric disorders, including major depression, even with a prospective study design. Long working hours were associated with a higher risk of myocardial infarction, diabetes mellitus and hypertension. There is evidence that the job demands-control model, as well as the use of new technology at work, is associated with higher levels of blood pressure and serum lipids among Japanese working populations. Fibrinolytic activity, blood glucose levels, immune functions and medical consultation rates were also affected by job stressors. It is further suggested that Japanese workers tend to suppress expression of positive feelings, which results in apparently higher psychological distress and lower job satisfaction among Japanese workers compared with workers in the U.S. Future epidemiologic studies in Japan should focus more on a prospective study design, theoretical models of job stress, job stress among women, and cultural difference and well-designed intervention studies of various types of worksite stress reduction.

Work stress and depressive symptoms among Japanese information systems managers.

The aim of the present study is to investigate the task-specific work stressors of IS (Information Systems) managers and to analyze the effect of these work stressors on depressive symptoms among these managers. A questionnaire including 33 items on work stressor was designed. Three hundreds of samples were gathered. The response-rate was 66.4%. Factor analysis suggested that these 33 items were categorized into 8 factors; job-overload, project-management, mental-rewards, job-latitude, communication with users, career development, technical difficulty, and work-environment. Eight work stressor scores were constructed using this Factor analysis. Using the 8 stressor-scores, and 6 items of background data, multiple regression analysis was conducted on the depressive symptoms score. Depressive symptoms were assessed using the Center for Epidemiologic Studies-Depression (CES-D) scale. The results showed that the factors of project-management, mental-rewards, and job-overload had significant effect on depressive symptoms (p < 0.01). It is indicated for the first time that software project management affects depressive symptoms in systems managers.

Perceived job-stress and blood pressure increase among Japanese blue collar workers: one-year follow-up study.

To investigate the relationship between job-stress and blood pressure increase, 373 male blue collar workers without hypertension were followed for one year. 5 kinds of perceived job-stress were assessed by means of mailed questionnaires. Stepwise multiple regression analysis was conducted to examine significant determinants of blood pressure increases during follow-up. Job-stress due to complicated machine operation was found to be a significant predictor of diastolic blood pressure increase independent of other significant factors, i.e., systolic and diastolic blood pressure at the beginning of the follow-up, age, total serum cholesterol, alcohol consumption, type A behavior and family history of hypertension. Job-overload, physical discomfort, human relations and job-dissatisfaction, on the other hand, bore no significant relation to systolic and diastolic blood pressure increases. The results suggest that the use of production machines involving complicated operations and newly developed technology might be a risk factor for high diastolic blood pressure.

Job stressor-mental health associations in a sample of Japanese working adults: artifacts of positive and negative questions?

To examine whether positive and negative components of mental health were differently related to job stressors and life events, correlational analyses were conducted using data for the GHQ-12 and some scales of the NIOSH Generic Job Stress Questionnaire collected from 765 workers in Japan. Six positive items and six negative items of the GHQ-12 were summed up for positive and negative components of mental health (GHQ-POS, GHQ-NEG). The GHQ-POS was significantly correlated with only positively-oriented job stressors. The GHQ-NEG was significantly correlated with only negatively-oriented job stressors. Most correlations were significantly different between GHQ-POS and GHQ-NEG. This correlation pattern resulted in smaller, but significant, correlations between job stressors and the GHQ-12. These results may reflect "measuring similarity" due to item-wording. Detailed inspection suggested that GHQ-POS and GHQ-NEG, as well as positively- and negatively-oriented job stressors, were not attributable only to positive affectively or negative affectivity, respectively. Work-related events showed higher correlations with all mental health variables than their job stressors' counterparts. For females, mental health variables were seldom correlated with job stressors, but significantly correlated with life events. These results might indicate the superiority of "event-type stress measure" as compared to perceived rating scale in assessing job stressors. Further direction was discussed.

Effects of mailed advice on stress reduction among employees in Japan: a randomized controlled trial.

We conducted a randomized controlled trial (RCT) to examine the effects of mailed advice on reducing psychological distress, blood pressure, serum lipids, and sick leave of workers employed in a manufacturing plant in Japan. Those who indicated higher psychological distress (defined as having GHQ scores of three or greater) in the baseline questionnaire survey (n = 226) were randomly assigned to an intervention group or a control group. Individualized letters were sent to the subjects of the intervention group, informing them of their stress levels and recommending an improvement in daily habits and other behaviors to reduce stress. Eighty-one and 77 subjects in the intervention and control groups, respectively, responded to the one-year follow-up survey. No significant intervention effect was observed for the GHQ scores, blood pressure, serum lipids, or sick leave (p > 0.05). The intervention effect was marginally significant for changes in regular breakfasts and daily alcohol consumption (p = 0.09). The intervention effect was marginally significant for the GHQ scores among those who initially did not eat breakfast regularly (p = 0.06). The study suggests that only sending mailed advice is not an effective measure for worksite stress reduction. Mailed advice which focuses on a particular subgroup (e.g., those who do not eat breakfast regularly) may be more effective.

Sleep problems in white-collar male workers in an electric equipment manufacturing company in Japan.

In order to clarify poor sleep habits and prevalence in sleep problems (disturbances) of healthy male white-collar workers and the relationship of these to age and job type, a total of 1,161 Japanese employees of an electric equipment manufacturing company (aged 23 to 59, mean 37 years) were surveyed by means of a mailed questionnaire. The workers were asked about eleven sleep habits. They were also divided into four groups according to age and job type: 23-29 (n = 226), 30-39 (n = 597), 40-49 (n = 225) and 50-59 (n = 113); managerial (n = 209), professional (n = 336), technical (n = 475) and clerical (n = 134). In this study, the sleep problems were defined as who had at least one of the following four poor sleep habits: 1) taking more than 30 minutes to fall asleep, 2) awakening during sleep (ADS) almost every day, 3) early morning awakening (EMA) almost every day, and 4) excessive daytime sleepiness (EDS) at work almost every day. Analyses showed that sleep problems were present in 26.0% of workers; the problems were most serious among workers aged 50 years and more (36.0%) which may be due to a significant increase in the prevalence rate of EMA. The results revealed that sleep problems are common in male white-collar daytime workers. The findings also suggest a need for increased attention to sleep problems in older workers and younger ones with EDS at work.

Job-stress and medical consultation rates for physical illness among blue collar workers of an electrical factory in Japan: a four-year prospective follow-up study.

To investigate the relationship between job-stress and medical consultation rates for physical illness, a prospective study was conducted for male blue workers of an electrical factory in Japan. 8 job-stress variables and 8 possible confounders were assessed by means of mailed questionnaires in the initial study; 375 workers without medical history of illness were followed for four years; they were interviewed once a year and medical consultations for physical illness were recorded. Age-adjusted rates of medical consultation during the four-year period were significantly higher in the subjects with higher job-dissatisfaction scores than in those with lower job-dissatisfaction scores (p less than 0.05). The results of the multiple logistic regression analysis indicated that job-dissatisfaction together with age and education was significantly correlated with medical consultation (p less than 0.05). The results suggest that job-dissatisfaction is a potential factor for medical consultation in Japanese blue collar workers.

Shift work-related problems in 16-h night shift nurses (1): Development of an automated data processing system for questionnaires, heart rate, physical activity and posture.

To assess the shift work-related problems associated with a 16-h night shift in a two-shift system, we took the following important factors into consideration; the interaction between circadian rhythms and the longer night shift, the type of morningness and eveningness experienced, the subjective sleep feeling, the subjects' daily behavior, the effectiveness of taking a nap during the long night shift, and finally the effectiveness of using several different kinds of measuring devices. Included among the measuring devices used were a standard questionnaire, repetitive self-assessment of subjective symptoms and daily behavior at short intervals, and a continuous recording of such objective indices as physical activity and heart rate. A potential problem lies in the fact that field studies that use such measures tend to produce a mass of data, and are thus faced with the accompanying technical problem of analyzing such a large amount of data (time, effort and cost). To solve the data analysis problem, we developed an automated data processing system. Through the use of an image scanner with a paper feeder, standard paper, an optical character recognition function and common application software, we were able to analyze a mass of data continuously and automatically within a short time. Our system should prove useful for field studies that produce a large amount of data collected with several different kinds of measuring devices.

Shift work-related problems in 16-h night shift nurses (2): Effects on subjective symptoms, physical activity, heart rate, and sleep.

We compared the shift work-related problems between 16-h night shift and 8-h evening/night shifts among nurses in a university hospital with respect to subjective symptoms, physical activity, heart rate (HR), and sleep. The nurses of one group (n = 20) worked a 16-h night shift under a rotating two-shift system, while those of the other group (n = 20) worked an 8-h evening or night shift under a rotating three-shift system. The 16-h night shift was staffed by three or four nurses who alternately took a 2-h nap during the shift, and had at least one day off after each shift. Subjective symptoms and daily behavior were measured every 30 min by the nurses before, during, after each shift as well as during days off using a time-budget method. Also, physical activity, heart rate (HR), and posture were recorded during shifts. The results showed similar or lower levels of sleepiness, difficulty in concentration, fatigue, physical activity, and HR during the 16-h shift compared to the 8-h shifts. No differences in subjective symptoms between the two shift schedules were observed before or after the shifts or during days off. The main sleep was longer after the shifts and during days off in the 16-h shift group than in the 8-h shift group. Our results suggest that the work-related problems in 16-h night shift nurses may not be excessively greater than those in 8-h evening/night shift nurses, as long as appropriate countermeasures are taken during and after the extended shift.

[A six-year follow-up study of childhood behavior problems].

In order to study the outcome of childhood behavior problems and to investigate relationships between those behavior problems and mental health problems in later years, a survey which was conducted in 1977 was repeated after six years. Subjects were randomly selected children aged from three to seven years living in Bunkyo-ku in Tokyo in 1977. Out of 279 children, responses to the questionnaire were obtained for 201 children, with 39 refusing to co-operate and 39 having left the area. The main results were as follows: 1. Comparison of prevalence rates of individual behavior problems occurring in early childhood (from 3 to 7 years old), showed that behaviors such as overactivity, "difficult to control", persistence, stubbornness and poor relations with unfamiliar persons decreased rapidly with age. On the other hand, hypoactivity, withdrawal and shyness increased. For problems occurring in late childhood (from 9 to 13 years old), the prevalence of poor concentration and passive behavior problems increased with age, while aggressive behaviors decreased. Behaviors such as thumb-sucking, nail-biting, bed-wetting and tics decreased. 2. Over the six years of this study, many behavior problems in areas of activity, mood, volition, human relations and abnormal symptoms showed significant persistence, although the degree of the persistence was not very strong. 3. Significant relationships between behavior problems observed at age three to seven years and mental health problems such as refusal to attend school and antisocial behaviors after six years were not seen.

Job strain and arterial blood pressure, serum cholesterol, and smoking as risk factors for coronary heart disease in Japan.

OBJECTIVE: To determine the effects of the job demands-control model on arterial blood pressure, serum total cholesterol, and smoking in male daytime and rotating-shift workers in Japan. METHODS: The survey was conducted for all employees of an electrical factory in Japan using a mailed questionnaire concerning three job stressors, i.e., job overload, work-pace control, and work-site social support. A blood sample was taken at the same time. Data on 1703 male daytime workers and 1 173 male rotating-shift workers were analyzed. Multiple logistic regression or analysis of covariance (ANCOVA) were employed to determine the effects of the job stressors on systolic and diastolic blood pressure, serum total cholesterol, and smoking with control for other covariates. RESULTS: Among daytime workers, systolic and diastolic blood pressures were highest in the "high-strain" (i.e., higher job overload + lower work-pace control) group; ANCOVA indicated that a two-way interaction between job overload and work-pace control was significant (P < 0.01). This tendency was not observed among rotating-shift workers. The number of cigarettes smoked per day was greater in groups with lower work-pace control and lower work-site social support among daytime workers (two-way interaction between these two job stressors, P < 0.05); it was greater in groups with lower work-site social support among rotating-shift workers (main effect of work-site social support, P < 0.05). CONCLUSIONS: Our study suggest that job strain as defined in the job demands-control model is associated with increased systolic and diastolic blood pressures in male daytime workers in Japan. Smoking might be affected by lower work-site social support.

Relations of work stress to alcohol use and drinking problems in male and female employees of a computer factory in Japan.

To examine the effects of work stressors on alcohol use and drinking problems as well as a model of stress-induced drinking in Japanese male and female workers, a total of 2581 employees of a computer factory were surveyed using mailed questionnaires. Five psychosocial work stressors, overtime, rotating shift, frequency of drinking, amount of alcohol consumed per drinking occasion, and drinking problems, and depressive symptoms were assessed. The hierarchical linear and logistic regression analyses were conducted in 1043 male and 255 female current drinkers aged 20 years or older. The results suggested that overtime and lack of intrinsic work rewards are main factors for heavy and problem drinking in Japanese male workers and that ambiguity about job future is a factor for heavy drinking in Japanese female workers. However, the model of stress-induced drinking was supported neither in males nor in females, suggesting that the effects of these work stressors on heavy and problem drinking are not mediated by depressive symptoms.

[Relationship between health practices and depressive mood among industrial workers].

In order to investigate the relationship between health practices and depressive mood, a survey was made by mail questionnaire on 3,987 industrial workers, which included items on 8 health practices and Zung Self-rating Depression Scale (Zung SDS). A total of 3,160 or 79.3% responded to the questionnaire. Multivariate analysis was employed to control the effects of possible confounders, such as demographic, job- and health-related variables. As the results, the following four health practices were found to be significantly related to low depressive score in male cases (N = 2,779): eating breakfast regularly, habitual physical activity, moderate alcohol consumption, and obesity not less than -10%. The following three health practices were found in female cases (N = 381) to be significantly related to low depression score: sleeping regularly 7-8 h per night, habitual physical activity, and non-smoker. It is considered that these health practices might decrease depressive mood, but further analysis is needed to determine their causal relationships because of the cross-sectional design of the present study.

Prevalence and demographic correlates of alcohol-related problems in Japanese employees.

To examine the relationship of basic sociodemographic characteristics to alcohol-related problem in Japanese employees, a questionnaire survey was conducted of a total of 2,581 employees of a computer factory in a suburb of Tokyo. The questionnaires included items on gender, age, marital status, social class (i.e., education, family income and occupation), alcohol consumption, and the Kurihama Alcoholism Screening Test (KAST). Data from 1098 male and 265 female current drinkers aged 20 years or older were analyzed; 15% and 6% of the male and female subjects, respectively, were classified as having alcohol-related problems on the basis of the KAST score (13% and 4% of the entire study population, respectively). Multiple logistic regression analysis indicated that alcohol-related problems were more prevalent in the less educated, managers and those who had a high alcohol consumption. The results suggested that education and occupation are important factors related to alcohol-related problems in Japanese employees.

Assessment of job stress dimensions based on the job demands- control model of employees of telecommunication and electric power companies in Japan: reliability and validity of the Japanese version of the Job Content Questionnaire.

To investigate the reliability and validity of 4 selected scales from the Japanese version of the Job Content Questionnaire (JCQ. Karasek, 1985)-decision latitude, psychological demand, supervisor support, and coworker support-a survey was conducted on a total of 626 employees of telephone and electric companies in Japan. The survey questionnaire was composed of 22 items. Data from 472 male and 108 female respondents were analyzed. Cronbach's alpha coefficients for the four JCQ scales ranged from .61 to .89 for men and from .65 to .87 for women. Scree plots based on factor analyses of scale items indicated that one major factor explained 30% to 75% of each scale variance in men and women. Factor structures of the 22 items for men and women were consistent with those theoretically expected Distributions of the decision latitude scores among occupations for men and women were similar to those in the U.S. national samples; the scores significantly and positively correlated with occupational class. It is suggested that the JCQ scales are reliable and valid instruments for assessing job stressors in a Japanese working population.

Direct and buffering effects of social support on depressive symptoms of the elderly with home help.

The purpose of the present study was to examine the prevalence of depressive symptoms on the Center for Epidemiologic Studies Depression Scale (CES-D) and the effect of life stressors or social support on depressive symptoms in 303 elderly people receiving social services at home. We conducted a questionnaire survey six times with a 1-month interval. In the initial wave of questionnaires, 92 (31%) scored 16 points or above on the CES-D, indicative of a risk for depression. Before life stressors, subjects with low-level support showed significantly more severe depressive symptoms than those with high-level support. Subjects with low-level support were significantly more depressive after life stressors than they had been before, whereas those with middle- and high-level support showed no such difference. The former and latter results seem to suggest the direct and buffering effects of social support on depressive symptoms, respectively.

Job stress, social support at work, and insomnia in Japanese shift workers.

A cross-sectional study was conducted to clarify the contribution of psychological job stress to insomnia in shift workers. A self-administered questionnaire concerning job stress, sleep, depressive symptoms and lifestyle factors was submitted to a sample of 530 rotating shift workers of age 18-59 years (mean age 27) in an electric equipment manufacturing company. Perceived job stress, i.e., job demands, job control and social support at work, was assessed using the Japanese version of the Job Content Questionnaire. Insomnia was regarded as prevalent if the workers had at least one of the following symptoms in the last year; less than 30 minutes to fall asleep, difficulty in maintaining sleep, or early morning awakening almost everyday. Overall prevalence was 37.8%. Logistic regression analyses while adjusting relevant factors showed that lower social support at work was significantly associated with a greater risk of insomnia than the higher social support (adjusted OR 2.5). Higher job strain with lower social support at work increased the risk, compared to lower strain with higher support at work (crude OR 1.8; adjusted OR 1.5). Our findings suggest the low social support at work independently associated with insomnia in shift workers.

Job strain, social support in the workplace, and haemoglobin A1c in Japanese men.

OBJECTIVES: To examine the association between job strain (defined in the model of job demands and job control) and social support at the workplace with levels of glycosylated haemoglobin A1c (HbA1c) METHODS: All male employees aged 40-60 in a manufacturing firm, Japan, were invited to take part in the study. A blood sample was taken from the participants and HbA1c (%) was measured. Job strain and social support at the workplace were assessed with the job content questionnaire (JCQ). After excluding those who had a history of diabetes mellitus or other chronic diseases, data from 268 male day workers were analyzed. RESULTS: Age adjusted average concentrations of HbA1c were significantly higher in the highest quartile group of job strain or the lowest quartile group of social support at the workplace (p<0.05). Multiple linear regression analysis indicated that job strain was significantly and positively related to HbA1c (p<0.05), whereas social support at the workplace was significantly and negatively related to HbA1c (p<0.05), both after controlling for other covariates. CONCLUSIONS: Greater job strain and lower social support at the workplace may be associated with increased concentrations of HbA1c. Increased blood glucose may be a physiological mediator between job strain or social support at the workplace and coronary heart disease.