[Development of a measure to assess stress underestimation beliefs].

Stress estimation is involved in the production of stress management behavior. Stress underestimation could hinder efforts to adequately manage stress. This study developed a measure to assess stress underestimation beliefs. Questionnaire surveys were conducted by mail twice on 2,340 adults aged from 20 to 65 years. The data from the surveys were subject to factor analysis, from which we developed a 12-item scale to assess stress underestimation beliefs (SUB). The SUB included four subscales: "Excessive self-efficacy for managing stress," "Insensitivity to stress," "Overgeneralization of stress," and "Evasive attitude towards stress." The SUB had adequate internal consistency. Higher SUB scores were associated with being in the precontemplation stage of change in terms of stress management behaviors, working long overtime hours (more than 81 hours per month), and having fewer self-reported stress symptoms. The SUB is potentially useful for assessing stress underestimation in the context of stress management.

[A two-year program to promote participatory workplace environmental improvements at small enterprises with fewer than ten employees].

OBJECTIVE: This study aimed to determine the influence of participatory workplace environmental improvement program on reducing job stress and workers' psychological distress at small enterprises (i.e., less than 10 employees). Furthermore, this study aimed to clarify important factors for success of this program as well. METHODS: The model program was tested in a small enterprise with eight employees between October 2014 and January 2017. Moreover, five employees participated in the annual work environment improvement workshops for two consecutive years. During both years, the New Brief Job Stress Questionnaire (80-item version) was used to measure work-related stress before (baseline) and after (post-three months and post-12 months) the workshops. To assess the extent of an intervention effect, the questionnaire data were analyzed using the Friedman test and the multiple comparison test annually. In addition, continuous data were analyzed during the two years. The statistical significance of the differences across time was determined at the p < .10 cutoff value because the number of participants was small. The effect size was also calculated. The participants were interviewed regularly. RESULTS: For both years, the employees implemented action plans within one month of completing the workshops. In the first year, the data for the Friedman test indicated a significant change in role conflict, job resources (workgroup-level), respect for individuals, fair personnel evaluations, work-self balance (positive), workplace social capital, and job satisfaction. In the multiple comparison test, significant changes manifested in role conflict and workplace social capital. In the second year, significant changes were found regarding role conflict and fair personnel evaluations for the Friedman test, demonstrating significant changes in role conflict in the multiple comparison test. As per the two-year survey results, the Friedman test indicated significant changes in role conflict, respect for individuals, and fair personnel evaluations, while the multiple comparison test demonstrated no significant changes. Over time, favorable changes were found regarding role conflict in the first year; however, undesirable changes were found regarding the other statistically significant items. The interviews revealed both positive and negative opinions. CONCLUSIONS: This study found the effects of the participatory workplace environment improvement program to be limited. Thus, the program should be improved to reduce its adverse effects as well as the participants' negative opinions.

Association of active and passive smoking with sleep disturbances and short sleep duration among japanese working population.

BACKGROUND: The relationship between passive smoking and sleep is uncertain. PURPOSE: To examine the association of passive/active smoking with sleep disturbances. METHOD: 732 women and 1,896 men, working in a suburb of Tokyo, were surveyed using a self-administered questionnaire. Information on smoking, passive smoking exposure, and sleep was elicited. Exposure levels to passive smoking were assessed separately at work and at home as no, occasional, or regular exposure. Risk of sleep disturbances according to smoking status was estimated using logistic regression with odds ratios (OR) and 95% confidence intervals (CIs) as measures of association. RESULTS: Compared to never smokers, odds of difficulty awakening in the morning (DAM) in current smokers were significantly higher for women (OR 1.95) and men (OR 1.50), while increased difficulty initiating sleep (OR 1.88) and decreased early morning awakening (OR 0.31) were found only in women. Never smoking men occasionally exposed to passive smoking at work but not at home had increased odds (OR 1.81) of short sleep duration (SSD, < 6 h) than unexposed counterparts. CONCLUSIONS: The analyses suggest that exposure to passive smoking at work is associated with SSD in men, while current smoking relates to various subtypes of sleep disturbances in both sexes.

Job strain and smoking cessation among Japanese male employees: a two-year follow-up study.

The purpose of the present study was to assess the association between job strain and smoking cessation among Japanese male employees. In 1997, a baseline questionnaire was given to 2,625 (2,113 males and 512 females) employees of an electronics firm in Gifu Prefecture, Japan. The self-administered questionnaire was a set of questions on smoking habits and consisted of items on socio-demographic variables and smoking habits, including the Japanese version of the Job Content Questionnaire (JCQ). The JCQ consists of scales of job control, job demand, supervisory support, coworker support, job insecurity, physical demands, and isometric load. A total of 733 male smokers were then followed for 2 years, with 446 completing a follow-up questionnaire in 1999 (follow-up rate, 61%). Logistic regression analyses were performed to examine associations between job strain and smoking cessation. Among the 446 participants, 38 had quit smoking. After adjusting for age ((odds ratio: OR) = 0.38, 95% (contidence interval: CI) = 0.15-0.94), men with a high level of physical demands at baseline showed a lower smoking cessation rate at follow-up than did those with a low level. However, when adjustments were made for age and other socio-demographic variables, the odds ratio of smoking cessation showed marginal significance (OR = 0.45, 95% CI = 0.16-1.29). There was no significant association between other job strain variables and smoking cessation at the 2-year follow-up. No significant association was found between job strain and change in the number of smoked cigarettes per day. The present study did not support the hypothesis that higher levels of job stressors are associated with a lower rate of smoking cessation among men.

Perceived job stress and sleep-related breathing disturbance in Japanese male workers.

To examine the association of job stress with sleep-related breathing disturbance (SBD), a cross-sectional sample of 1940 males aged 17-83 (mean 45) years in 292 small and medium-sized enterprises in Japan were surveyed by means of a self-administered questionnaire. Perceived job stress was evaluated by the Japanese version of the Generic Job Stress Questionnaire developed by the US National Institute for Occupational Safety and Health, which included 13 job stress variables. Participants were divided into thirds according to their job stress scores. SBD was assessed by the question "Have you ever felt difficulty breathing during sleep or has anyone in your family told you that you have such difficulty?" SBD was defined as presence of symptoms more than once a month. Risk of SBD through job stress was estimated using logistic regression with odds ratios (ORs) and 95% confidence intervals (CIs) as measures of association. Prevalence of study-defined SBD was 6.7%. Participants who perceived the lowest level of social support from supervisors, and highest levels of job future ambiguity, interpersonal conflict at the workplace, job dissatisfaction, variance in workload, and quantitative workload had significantly increased risk of SBD after adjusting for potential confounders. High depressive symptoms, as measured by Center for Epidemiologic Studies Depression scale scores of 16 or higher, were also significantly associated with increased SDB. Although the results should be considered preliminary because of the self-reporting and cross-sectional design, data suggest that exposure to high job stress could be a possible risk factor for developing or aggravating SBD. Results also indicate that job stress should be considered when evaluating SBD in occupational and clinical settings.

Relationship between cumulative effects of smoking and memory CD4+ T lymphocyte subpopulations.

Previous studies have found that smoking is a strong factor that increases peripheral blood CD4+ T lymphocytes. However, most studies did not assess the cumulative long-life exposure of smoking on differential lymphocyte populations. In this study, to clarify the association of smoking habits and circulating lymphocytes, we conducted a cross-sectional study of 60 male current smokers. Smoking status was estimated by number of cigarettes smoked per day, smoking years, and Brinkman Index (BI) as calculated by multiplying the number of cigarettes smoked per day by the smoking years. Counts of CD4+CD45RO+CD69+ T and CD4+CD45RO+ T lymphocytes were strongly and positively correlated with BI and remained highly significant after controlling for alcohol drinking, leisure-time physical activity, and caffeine intake (r(p)>.465, p<.001). These lymphocytes were also significantly correlated with the number of cigarettes smoked per day and smoking years, but the association was weaker than the BI. The findings suggest that the CD4+CD45RO+CD69+ T and CD4+CD45RO+ T lymphocytes are sensitive to cumulative effect of smoking, and may serve as a potential immuno-biomarker for active smoking.

Sickness absence in relation to psychosocial work factors among daytime workers in an electric equipment manufacturing company.

Associations between psychosocial work factors and sickness absence were investigated in a cross-sectional study of 833 daytime workers. Participants completed a questionnaire regarding psychosocial work factors using the US National Institute for Occupational Safety and Health Generic Job Stress Questionnaire (job control, quantitative workload, cognitive demands, variance in workload, intragroup conflict, intergroup conflict, supervisor support, coworker support, family support, job satisfaction and depressive symptoms) and the number of days of sickness absence within the previous year. Multivariate analyses of covariance with age and occupation as covariates (MANCOVA) were used to test the relationships between psychosocial work factors and sickness absence stratified by sex. In men, the age-adjusted MANCOVA showed that, quantitative workload was highest in the 0.5-4.5 d of sickness absence group (p<0.001). However, the levels of stress reactions (job satisfaction and depressive symptoms) in this group were almost identical to the levels recorded in the no sickness absence group. In contrast, low levels of job control (p<0.01), supervisor support (p<0.05), and job satisfaction (p<0.01) and higher symptoms of depression (p<0.001) were associated with 5 d or more sickness absence. In women, only high job satisfaction was associated with 5 d or more sickness absence (p<0.10). This study suggests that appropriate use of sickness absence at times of being exposed to high quantitative workload may help male workers to recover from stressful situations.

Indoor exposure to natural bright light prevents afternoon sleepiness.

STUDY OBJECTIVES: The present study examined the effects of indoor exposure to natural bright light on afternoon sleepiness. DESIGN: Participants took part in 3 experimental conditions: (1) a natural bright light condition in which they carried out performance and arousal tests sitting near a window (3260.0 +/- 1812.43 lux) from 12:40 PM to 1:10 PM, (2) a nap condition in which they were provided a nap opportunity for 20 minutes from 12:45 PM, and (3) a control condition in which they performed the tests in less than 100 lux surroundings from 12:40 PM to 1:10 PM. Before and after each treatment, the same series of tests were administered. SETTING: A temperature- and light-controlled sleep laboratory. PARTICIPANTS: Sixteen healthy female paid volunteers aged 33 to 43 (38.1 +/- 2.68) years. INTERVENTIONS: Indoor natural bright light and a short nap. MEASUREMENTS AND RESULTS: Arousal levels were measured by the Psychomotor Vigilance Task, Alpha Attenuation Test, Karolinska Drowsiness Test, and Karolinska Sleepiness Scale. The tests were repeated every 30 minutes from 11:00 AM to 4:10 PM. Ambient light intensity was maintained at less than 100 lux, except during natural bright light exposure. Short-term exposure to natural bright light significantly improved afternoon arousal levels, as measured by the Karolinska Drowsiness Test and Alpha Attenuation Test, the effects of which continued for at least 60 minutes (1:10-2:10 PM). However, no significant differences were observed between conditions for Psychomotor Vigilance Test performance. CONCLUSIONS: Brief indoor exposure to natural bright light may decrease afternoon sleepiness. This technique of light could be used in work settings in which napping is not permitted.

Validation of the Karolinska sleepiness scale against performance and EEG variables.

OBJECTIVE: The Karolinska sleepiness scale (KSS) is frequently used for evaluating subjective sleepiness. The main aim of the present study was to investigate the validity and reliability of the KSS with electroencephalographic, behavioral and other subjective indicators of sleepiness. METHODS: Participants were 16 healthy females aged 33-43 (38.1+/-2.68) years. The experiment involved 8 measurement sessions per day for 3 consecutive days. Each session contained the psychomotor vigilance task (PVT), the Karolinska drowsiness test (KDT-EEG alpha & theta power), the alpha attenuation test (AAT-alpha power ratio open/closed eyes) and the KSS. RESULTS: Median reaction time, number of lapses, alpha and theta power density and the alpha attenuation coefficients (AAC) showed highly significant increase with increasing KSS. The same variables were also significantly correlated with KSS, with a mean value for lapses (r=0.56). CONCLUSIONS: The KSS was closely related to EEG and behavioral variables, indicating a high validity in measuring sleepiness. SIGNIFICANCE: KSS ratings may be a useful proxy for EEG or behavioral indicators of sleepiness.

Non-fatal occupational injury among active and passive smokers in small- and medium-scale manufacturing enterprises in Japan.

Active smoking is a risk factor for occupational injury, whereas its association with passive smoking is unknown. To evaluate the contribution of active and passive smoking to non-fatal occupational injury in manufacturing sectors, 2302 randomly selected workers aged 16-83 years working in 244 small- and medium-scale enterprises in Yashio city, Japan, were surveyed by means of a self-administered questionnaire. Smoking history, exposure to passive smoking, and occupational injury were evaluated by self-report. Exposure levels to passive smoking were assessed separately at work and at home as never, occasional, or regular exposure. Overall, 61.4% of men and 22.3% of women were current smokers. Among never smokers, 62.2% of men and 68.6% of women reported exposure to passive smoking either at work or home. Prevalence of occupational injuries was 36.2% for never, 43.3% for former, and 41.2% for current smokers among men and 19.7% for never, 22.2% for former, and 25.2% for current smokers among women. Among never smoking men, odds ratios (ORs) of occupational injury were 2.11 when regularly exposed to passive smoking at work or at home (p=0.025), 2.27 at work (p=0.015), and 3.08 at home (p=0.106), in comparison to never smoking men who were never exposed to passive smoking either at work or at home (referent group). These associations were attenuated to be non-significant, after controlling for potential confounders. Never smoking men with occasional exposure to passive smoking were not significant ORs (1.11-1.19). In contrast, current and former smoking men had significant increases in adjusted ORs (1.57-2.00). In women exposed to smoking there was a non-significant increase in occupational injury. The present study indicates an expected increase in the risk of, occupational injury for current and former smoking men and suggests that exposure to passive smoking is a possible risk factor for never smoking men.

Psychosocial work characteristics predicting daytime sleepiness in day and shift workers.

Characteristics of work organization other than working time arrangements may contribute importantly to daytime sleepiness. The present study was designed to identify the psychosocial factors at work that predict daytime sleepiness in a sample of day and shift workers. Participants working at a pulp and chemical factory completed an annual questionnaire regarding psychosocial factors at work using the U.S. National Institute for Occupational Safety and Health Generic Job Stress Questionnaire (i.e., quantitative workload, variance in workload, job control, support from supervisor, coworkers, or family/friends, job satisfaction, and depressive symptoms), as well as daytime sleepiness (through the Epworth Sleepiness Scale [ESS]) and sleep disturbances for three years starting in 2002 (response rates, 94.6-99.0%). The present analysis included 55 day workers (11 women) and 57 shift workers (all men) who participated in all three years of the study, worked under the same work schedule throughout the study period, and had no missing data on any of the daytime sleep items. A repeated-measures analysis of covariance (ANCOVA) was used to test the effects of work schedule (day vs. shift work) and psychosocial factors at work in 2002 on the ESS scores in subsequent years, with sleep duration, insomnia symptoms, chronic diseases, and sleepiness levels at baseline as covariates. Given significant and near-significant interactions of work schedules with psychosocial factor or study year, the ANCOVA, with the factors of psychosocial work characteristics and study year, was performed by type of work schedule. The results indicated a significant main effect of psychosocial work characteristics (p = 0.010, partial eng2 = 0.14) and an almost significant main effect of study year (p = 0.067, partial eng2 = 0.06) and interaction between psychosocial work characteristics and study year (p = 0.085, partial eng2 = 0.06) for variance in workload among the day work group. The day workers reporting high variance in workload in 2002 exhibited significantly higher ESS scores in 2003 and 2004 than did those reporting low variance in workload. The ANCOVA for the shift work group showed a main effect of psychosocial work characteristics for job satisfaction (p = 0.026, partial eng2 = 0.10) and depressive symptoms (p = 0.094, partial eng2 = 0.06) with the interaction between psychosocial work characteristics and study year for job satisfaction (p = 0.172, partial eng2 = 0.04) and depressive symptoms (p = 0.035, partial eng2 = 0.07). The shift workers with low job satisfaction and high symptoms of depression in 2002 showed significantly greater ESS scores in 2003 and/or 2004 than did those with opposite characteristics. These results may suggest a potential predictive value of variance in workload for day workers as well as job satisfaction and depressive symptoms for shift workers with respect to daytime sleepiness. The present findings may imply that redesigning these aspects of work environment would be of help in managing daytime sleepiness.

The prevalence and correlates of occupational injuries in small-scale manufacturing enterprises.

Workers involved in small-scale manufacturing businesses are known to comprise a high-risk population for occupational injury. The present study investigated the prevalence and correlates of occupational injury in this population. A self-administered questionnaire that solicited answers about occupational information including injury, demographic characteristics, health conditions and lifestyle factors was collected from a sample of 1,298 workers in 228 small-scale manufacturing enterprises (defined as fewer than 50 workers) aged 16-78 (mean 46) yr in Yashio city, Saitama, Japan (response rate 65.5%). The enterprises were randomly selected from the 2000 edition of the city commercial directory corresponding to the distribution of types of businesses in the city. Occupational injury was assessed by asking subjects, ;Have you ever been injured during your work, including minor scratches and cuts in the previous 1-yr period?' The possible response was either ;yes' or ;no.' The prevalence of study-defined occupational injury among the workers was 35.6% (male 43.0%, female 17.9%). Among job types, manufacturing (44.2%) and driving (43.5%) had high rates of occupational injuries. Similarly, occupational injuries were high in the papermaking (54.5%) and machinery (47.7%) industries. For males, younger age, current or former smoking, insomnia symptoms, and disease(s) currently under treatment were correlated with injury, whereas for females, being unmarried, higher educational status, and insomnia symptoms were the correlating factors. Occupational injury is common among small-scale manufacturing businesses, and is associated with multiple controllable factors. Countermeasures such as prohibiting smoking during work, sleep health education, job safety training for young/inexperienced workers are appropriate methods for eliminating or reducing injuries.

Perceived sleepiness of non-shift working men in two different types of work organization.

Increased sleepiness at work is increasingly being focused on as a safety and health issue. However, research on workers' sleepiness is very limited in scope and the characteristics of work organization, including the impact of job stress, have not been fully addressed. A questionnaire survey was conducted to investigate the prevalence of daytime sleepiness and its associated factors among non-shift working men at two manufacturing businesses: Company A, having a rapid rate of development and growth, with 564 workers (19-61 yr old, mean age: 32.7, response rate: 81.4%); and Company B, long established, possessing a huge production facility, with 1,654 workers (20-63 yr old, mean age: 37.1, response rate: 78.2%). The prevalence of daytime sleepiness was 11.3% in company A and 16.8% in company B. Multivariate logistic regression analysis revealed that, in company A, perceived sleepiness was associated with long sleep duration on non-working days and high cognitive demands and, in company B, with insufficient daily sleep, single, and depression. Psychosomatic exhaustion resulting from jobs requiring high adaptivity due to rapid frequency of operational change as in company A may have the potential to become an important factor in perceived sleepiness. However, in a comparatively stable work organization, as in company B, increased sleepiness may be mainly linked to factors outside work. It is suggested that not only lifestyle and sleep habits, but also the characteristics and dynamics of a work organization should be a focus of attention when planning measures to prevent sleepiness at work.

Association between perceived social support and Th1 dominance.

Social support is supposed to have a positive health effect via alteration of immunity. In this study, associations between perceived social support and immune systems were examined. Immunological assessments, e.g. T cell count, Natural Killer cell count, Interferon-gamma, Interleukin-4, and psychological assessments, e.g. Generic Job Stress Questionnaire were conducted on male employees. Two-way (social support x job stressor) analyses of covariance controlling for age, smoking, alcohol consumption, and exercise revealed that there were main effects of perceived social support on NK cell counts, IL-4, and Th1/Th2 balance. On the other hand, interaction effects were observed on T cell counts and INF-gamma production in vitro. Social support affects immune function in a way that is consistent with both the direct and buffering hypotheses depending on the sources of support and the immune parameter.

Sleep-related risk of occupational injuries in Japanese small and medium-scale enterprises.

A cross-sectional study evaluated the contribution of daily sleep habits to occupational injuries. A self-administered questionnaire solicited answers about sleep, symptoms of depression, occupational injury, demographics, presence of diseases and lifestyle factors from 2,903 workers between the ages of 16-83 (mean 45) yr in small and medium-scale enterprises. Eight sleep habits were queried and dichotomized: 1) less or more than 6 hr of daily sleep, 2) taking more or less than 30 min to fall asleep (Difficulty initiating sleep; DIS), 3) awakening during sleep more or less than 3 times/wk (Difficulty maintaining sleep; DMS), 4) early morning awakening more or less than 3 times/wk (EMA), 5) definitely/somewhat difficulty waking up or not, 6) sleeping very poorly/not so well at night or not, 7) definitely/somewhat insufficient nightly sleep or not, and 8) difficulty in breathing during sleep more than once/week or less. Occupational injury was assessed by asking subjects 'Have you ever been injured during your work, including minor scratches and cuts (Yes/No)?' Both sleep and injury were assessed over the previous one year period. One-third of workers answered that they had experienced injury. Workers with sleep features of DIS, sleeping poorly at night, insufficient sleep, and insomnia had a significantly higher prevalence for injury after adjusting for multiple confounders. The findings suggest that poor nocturnal sleep habits are associated with self-reported occupational injury.

[Development of a checklist for evaluation of mental health activities at the workplace].

"The Checklist for Evaluation of Mental Health Activities at the Workplace" was developed for workplace staff evaluating mental health activities in their own workplace. The validity and reliability of the checklist were examined and criteria for evaluation were developed for workplace/organization/companies with 50 or more employees in Japan. The checklist initially included 33 items covering seven major domains of occupational mental health, with a four-point response option, based on the Japanese Guideline for Worker Mental Health in the Workplace and a relevant literature review. A questionnaire was send to 60 members of the Occupational Mental Health Committee (OMHC) of the Japan Society for Occupational Health to ask their opinions on the checklist and on the minimum requirement for each item on the checklist; 30 (50%) responded. A random sample of 1,335 workplaces from a contractor list of workplaces for worker compensation insurance and a questionnaire was send to the personnel department to fill in the checklist; 412 (31.5%) responded and data from 335 of them with 50 or more employees were analyzed. Some OMHC members felt that one of the items (concerning the Total Health Promotion program) should be dropped; thus the checklist was revised to include 32 items, still covering the seven domains. Based on the workplace survey data, most domain scales showed internal consistency reliability at an acceptable level; explanatory factor analysis yielded a four-factor structure that was well concordant with the hypnotized seven-domain structure. Three levels of adequacy of mental health activities were set for each domain scale: "red" (inadequate), "yellow" (minimal), and "green" (adequate). One third of occupational health professionals from 49 workplaces rated the evaluation result based on the checklist as concordant with their view; 95% of them said the checklist would be useful in promoting occupational mental health activities. The study indicated that the checklist had reliability (based on internal consistency reliability) and content- and construct-validity (based on expert opinions, a factor-structure concordant with empirical data, and evaluation by workplace staff). The checklist seems useful in promoting occupational mental health activities.

Socioeconomic determinants of bullying in the workplace: a national representative sample in Japan.

Bullying in the workplace is an increasingly recognized threat to employee health. We sought to test three hypotheses related to the determinants of workplace bullying: power distance at work; safety climate; and frustration related to perceived social inequality. A questionnaire survey was administered to a nationally representative community-based sample of 5,000 residents in Japan aged 20-60 years. The questionnaire included questions about employment, occupation, company size, education, household income, and subjective social status (SSS). We inquired about both the witnessing and personal experience of workplace bullying during the past 30 days. Among 2,384 respondents, data were analyzed from 1,546 workers. Multiple logistic regression analyses were used to examine the social determinants of workplace bullying. Six percent and 15 percent of the total sample reported experiencing or witnessing workplace bullying, respectively. After adjusting for gender and age, temporary employees (Odds Ratio [OR]: 2.45 [95% Confidence Interval (CI) = 1.03-5.85]), junior high school graduates (OR: 2.62 [95%CI: 1.01-6.79]), workers with lowest household income (OR: 4.13 [95%CI:1.58-10.8]), and workers in the lowest SSS stratum (OR: 4.21 [95%CI:1.66-10.7]) were at increased risk of experiencing workplace bullying. When all variables were entered simultaneously in the model, a significant inverse association was observed between higher SSS and experiencing bullying (p = 0.002). Similarly in terms of witnessing bullying; SSS was significantly inversely associated (p = 0.017) while temporary employees reported a significantly higher risk of witnessing bullying compared to permanent workers (OR: 2.25 [95%CI:1.04 to 4.87]). The significant association between SSS and experiencing/witnessing workplace bullying supports the frustration hypothesis. The power distance hypothesis was also partly supported by the finding that temporary employees experienced a higher prevalence of workplace bullying.

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

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.

Lifetime and 6-month prevalence of DSM-III-R psychiatric disorders in an urban community in Japan.

We conducted a community-based interview survey of a random sample of residents aged 20 years or older in an urban community in Japan using the University of Michigan Version of the WHO Composite International Diagnostic Interview for selected mood and anxiety disorders and alcohol abuse/dependence according to DSM-III-R. The final sample consisted of 1029 respondents (response rate, 57%). The lifetime and 6-month prevalences of selected mood, anxiety and alcohol use disorders were low in general. Alcohol abuse/dependence was more prevalent in men than in women. Younger respondents had a greater risk of generalized anxiety disorder and alcohol dependence. A greater risk of mood, anxiety and alcohol use disorders was observed among a recent birth cohort. We confirmed a lower prevalence of mood and anxiety disorders and alcohol use disorders in a community population in Japan than in Western countries, observations that were similar to previous ones in East-Asian countries. The patterns of demographic correlates and comorbidity are similar to those of most other countries.

Association of sickness absence with poor sleep and depressive symptoms in shift workers.

A cross-sectional study was conducted to evaluate the contribution of daily sleep habits and depressive symptoms to sickness absences of shift workers. A self-administered questionnaire that solicited answers about sleep, symptoms of depression, sickness absence, diseases/injuries, and lifestyle factors was submitted to a sample of 522 rotating shift workers between the ages of 18-59 (mean 27) yrs of an electric equipment manufacturing company. The seven features of sleep queried were daily hours of sleep, time to fall asleep, awakening during sleep, early morning awakening, sleep well at night, sufficiency of sleep, and excessive daytime sleepiness at work. The responses were assessed over the subject's previous 1-yr period. Each sleep feature, except daily sleeping hours, was dichotomized by the following responses: (1) taking more than 30min to fall asleep (difficulty initiating sleep; DIS), (2) awakening during sleep almost every day (difficulty maintaining sleep; DMS), (3) early morning awakening almost every day (EMA), (4) sleeping very poorly or not so well at night, (5) definite or somewhat insufficient nightly sleep, and (6) excessive daytime sleepiness at work almost every day (EDS). Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) scale. Sickness absence was calculated by asking subjects "How many days in total have you been absent from work due to sickness, including paid vacation, in the last 1-yr period?" The responses were divided into three groups that included no (0 days) sickness absences (reference group, n=235 subjects), 1 to 4 days (short-term, n=199 subjects), and 5 days or more (long-term, n = 88 subjects). Compared to the prevalence of sleep features of the reference group, workers with short-term absence showed a significantly higher prevalence of EMA with an odds ratio (OR) of 5.3, 95% confidence interval (CI) 1.3-22.0. Long-term absence was significantly associated with DMS (OR = 2.1, 95%CI 1.0-4.6), EMA (OR = 5.6, 95%CI 1.0-28.7), sleeping poorly at night (OR= 2.6, 95%CI 1.4-5.0), and high depressive symptoms (OR = 2.0, 95%CI 1.0-3.7) according to the CES-D score of >16, after adjusting for multiple confounding variables. These data point to an association between both the parameters of poor sleep and symptoms of deep depression when self-reported sickness absence is frequent. The association is particularly strong with long-term absence in male shift workers.