Longitudinal assessment of lifestyle factors associated with nonrestorative sleep in Japan.

OBJECTIVE: Nonrestorative sleep (NRS) is common in the general global population. This study surveyed the incident/remission rate of NRS and identified related lifestyle factors in a general Japanese adult cohort. METHODS: Data from a Japanese health check-based cohort between the fiscal years 2011 and 2018 were obtained. NRS was assessed through a single item question, and socio-demographic and clinical data were assessed through self-reports. To identify potential correlates of NRS incidence/remission, Cox regression analysis (or survival analysis) was performed. RESULTS: Among the 135 609 individuals surveyed at baseline, data from 93 548 were considered for analysis. NRS exhibited incidence and remission rates of 11.3% and 15.4%, respectively. New NRS incidence was predicted by eating fast (hazard ratio [HR]: 1.07, 95% confidence interval [CI]: 1.04-1.10), dining close to bedtime (HR: 1.33, 95% CI: 1.27-1.38), midnight snacking (HR: 1.09, 95% CI: 1.04-1.13), skipping breakfast (HR: 1.16, 95% CI: 1.10-1.22), non-regular exercise (HR: 1.12, 95% CI: 1.07-1.17), lower levels of physical activity (HR: 1.19, 95% CI: 1.14-1.24), and slow walking speed (HR: 1.34, 95% CI: 1.29-1.39), while heavy drinking was less predictive of NRS. However, the same factors (except for heavy drinking) were found to predict NRS remission. CONCLUSIONS: We found that unhealthy lifestyle behaviors, particularly dining close to bedtime and slow walking speed, were positively associated with NRS incidence, while they were negatively associated with NRS remission. These results can be useful in developing more effective health promotion policies to achieve good sleep.

Analysis of risk of medical errors using structural-equation modelling: a 6-month prospective cohort study.

BACKGROUND: Medical-error analyses have been conducted to determine the root cause of adverse events and near misses. More precise determination of the cause-and-effect relationship likely will require a prospective design path analysis including both direct and indirect effects. METHODS: The authors performed a 6-month prospective cohort study using structural-equation modelling (SEM). Of the 879 nurses approached, 789 (89.8%) were included in the final analysis. Potential predictors provided for analysis included age, years of nursing experience, mean frequency of night shifts per month, nursing-specific job stressors, degree of depression, frequency of feeling unskilled, feeling time pressure, feeling a lack of communication between self and other hospital staff members, frequency of suffering from sleep disturbance and frequency of feeling a decrease in attention. The authors regarded a latent variable composed of frequencies for near misses and adverse events as an outcome. RESULTS AND CONCLUSION: The SEM model constructed in this study suggested that potential root causes (exogenous variables directly or indirectly connected to the outcome which are not affected by other variables) were years of nursing experience, feeling unskilled, job stressors and sleep disturbance, with estimated standardised total (direct and indirect) effects of -0.22, 0.21, 0.008 and 0.005, respectively. A prospective design path analysis using the SEM model for both direct and indirect effects enabled a statistical exploration of root causes and estimation of their impact on the outcome. Our findings suggested such an analysis to be useful in devising countermeasures against medical errors.

[Medical safety and staff mental health].

Improvement in patient safety is a high-priority issue of great social import. Several studies have reported that most adverse events are due to errors of hospital staff, and emphasized the necessity of promoting countermeasures against medical errors. Root cause analysis (RCA) has been implemented to prevent such errors. However, the retrospective and qualitative nature of RCA is a limitation in scientific analyses examining causal relationships. We showed that prospective design path analysis using structural equation modeling (SEM) model for both direct and indirect effects enabled statistical exploration of root causes and estimation of their impact on the outcome. Our findings suggested such analysis to be useful in devising countermeasures against medical errors. The SEM model constructed in this study suggested that one of the potential root causes was sleep disturbance. We conducted a randomized crossover study whether or not brief bright light (BL) exposure on workday mornings can improve health, performance and safety in nurses with rapidly rotating shifts. Significant improvements were noted in the BL periods compared with the non-BL periods for self-assessed sleepiness at 10 : 00 on day-shift days, self-assessment of night sleep for day-shift days and for fatigue. Mean response time evaluated using the psychomotor vigilance task test (PVT) showed significant improvement in the BL periods compared with the non-BL periods. The frequency of perceived adverse events and near misses was also lower in the BL than in the non-BL periods, but not significantly so, possibly indicating that the one-month observation period was too short to achieve any significant success. Despite our study's limitations, we have effectively demonstrated the potential for preventing medical error risk among night-shift workers.

Effects of sleep hygiene education and behavioral therapy on sleep quality of white-collar workers: a randomized controlled trial.

Because poor sleep quality can reduce quality of life and increase prevalence of illness in workers, interventions are becoming increasingly important for businesses. To evaluate how sleep quality is affected by one-on-one behavioral modification when combined with group education, we conducted a randomized, controlled trial among day-shift white-collar employees working for an information-technology service company in Japan. Participants were randomly allocated to groups receiving either sleep hygiene group education (control group), or education combined with individual sleep modification training (one-on-one group). Occupational health professionals carried out both procedures, and sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). PSQI scores were obtained before and after the intervention period, and changes in scores were compared across groups after adjustments for age, gender, job title, smoking and drinking habits, body-mass index, and mental health as assessed using K6 scores. The average PSQI score for the control group decreased by 0.8, whereas that of the one-on-one group decreased by 1.8 (difference of 1), resulting in a significantly greater decrease in score for the one-on-one group (95% confidence interval: 0.02 to 2.0). These results show that, compared to sleep hygiene group education alone, the addition of individual behavioral training significantly improved the sleep quality of workers after only three months.

Randomized controlled trial on the effects of a combined sleep hygiene education and behavioral approach program on sleep quality in workers with insomnia.

To evaluate the effects of a combined sleep hygiene education and behavioral approach program on sleep quality in workers with insomnia, we conducted a randomized controlled trial at a design engineering unit in Japan. Employees evaluated for insomnia by the Athens Insomnia Scale (≥6 points) were divided into an intervention and control group. The intervention group received a short-term intervention (30 min) program that included sleep hygiene education and behavioral approaches (relaxation training, stimulus control, and sleep restriction) performed by occupational health professionals. We calculated differences in change in Pittsburgh Sleep Quality Index (PSQI) scores between the two groups from baseline to three months after the start of intervention after adjusting for gender, age, job title, job category, average number of hours of overtime during the study period, marital status, smoking habit, average number of days of alcohol consumption per week, exercise habits, K6 score, and baseline PSQI score. Results showed that the average PSQI score decreased by 1.0 in the intervention group but increased by 0.9 in the control group. Additionally, the difference in variation between the two groups was 1.9 (95% confidence interval: 0.6 to 3.4), which was significant. Taken together, these results indicate that the intervention program significantly improved the sleep quality of workers with insomnia.

Brief morning exposure to bright light improves subjective symptoms and performance in nurses with rapidly rotating shifts.

OBJECTIVE: To investigate whether or not brief bright light (BL) exposure on workday mornings can improve health, performance and safety in nurses with rapidly rotating shifts. METHODS: We conducted a randomized crossover study involving registered nurses at a teaching hospital working a two-shift system including the night shift. Participants were instructed to expose themselves to BL for 10 min on workday mornings. RESULTS: A total of 61 participants were enrolled in the present study. Thirty-one participants received BL exposure in the first month, and the other 30 received it in the second month. Significant improvements were noted in the BL periods compared with the non-BL periods for self-assessed sleepiness at 10:00 on day-shift days evaluated using the Karolinska Sleepiness Scale, self-assessment of night sleep for day-shift days using the Visual Analogue Scale and for fatigue assessed using the Checklist Individual Strength Questionnaire. The estimated mean difference for each scale (95% confidence interval) was -0.55 (-0.91, -0.20), 0.37 (0.04, 0.70) and -2.13 (-3.78, -0.48), respectively. Mean response time evaluated using the psychomotor vigilance task test (PVT) showed significant improvement in the BL periods compared with the non-BL periods. No statistically significant differences were observed for sleepiness at 14:00, depression, number of PVT lapses or frequency of perceived adverse events and near misses. CONCLUSION: Our findings suggest that brief BL exposure on mornings preceding a day shift is effective in improving sleepiness and performance during day-shift work, subjective nighttime sleep on day-shift days, and perceived fatigue for the preceding two weeks in rapidly rotating shift nurses.

Effect of brief sleep hygiene education for workers of an information technology company.

To investigate the effects of sleep hygiene education for workers of an information technology (IT) company, we conducted a controlled clinical trial providing 581 workers one-hour sleep hygiene education. The contents of the sleep hygiene education program were a review of sleep habits, provide sleep hygiene education, and the establishment of sleep habit goals. A self-report questionnaire was used to measure outcomes including the Pittsburgh Sleep Quality Index (PSQI), Karolinska Sleepiness Scale (KSS), Checklist Individual Strength (CIS), Center for Epidemiologic Studies for Depression (CES-D), and mean sleep duration on weekdays before and 4 wk after the intervention. A total of 391 participants were included in the analysis, with 214 participants in the sleep hygiene education group and 177 in the waiting list group. KSS score at 2 P.M. decreased by 0.42 points in the sleep hygiene education group, but increased by 0.08 points in the waiting list group, showing a significant effect size of 0.50 (95%CI, -0.97 to -0.04, p<0.05). PSQI score also improved, but the inter-group difference was not statically significant. The present study provides preliminary evidence that brief sleep hygiene education may improve afternoon sleepiness at work, but not sleep at night for IT workers.

Similarity in predictors between near miss and adverse event among Japanese nurses working at teaching hospitals.

Near miss-based analysis has been recently suggested to be more important in the medical field than focusing on adverse events, as in the industrial field. To validate the utility of near miss-based analysis in the medical fields, we investigated whether or not predictors of near misses and adverse events were similar among nurses at teaching hospitals. Of the 1,860 nurses approached, 1,737 (93.4%) were included in the final analysis. Potential predictors provided for analysis included gender, age, years of nursing experience, frequency of alcohol consumption, work place, ward rotation, frequency of night shifts, sleepiness during work, frequency of feeling unskilled, nurses' job stressors, working conditions, and depression. Variables for multivariate analysis were determined by bivariable analysis. Ordinal logistic analysis showed that predictors of near misses and adverse events were markedly similar. Parameters that were significantly related to both near misses and adverse events were years of experience, frequency of night shifts, internal ward, and time pressure (p<0.05 for all). The present study suggested that there was a negligible difference between choosing near miss- or adverse event-based analysis when identifying possible causes of adverse events in the medical field.

Differences in medical error risk among nurses working two- and three-shift systems at teaching hospitals: a six-month prospective study.

Shift work, including night work, has been regarded as a risk factor for medical safety. However, few studies have investigated the difference in medical error risk between two- and three-shift systems. A total of 1,506 registered nurses working shifts at teaching hospitals participated in this study to evaluate the difference in medical error risk between two- and three-shift systems. After adjustment for potential confounding factors using a log Poisson generalized estimating equation model, the results showed significantly higher frequencies of perceived adverse events over 6 months in the three-shift than in the two-shift system, with estimated mean numbers of adverse events of 1.05 and 0.74, respectively. Shorter intervals after night shifts and greater frequency of night shifts in three-shift systems, which reduce the recovery time from night shift work, may be linked to increased medical errors by nurses.

Sleep-disordered breathing and hypertension in Japanese steel workers.

Sleep-disordered breathing (SDB) is the major determinants of hypertension. Recent studies indicated sleep duration, in addition to shift work, were also associated with hypertension. But very little attention has been paid to these two factors when looking at the effects of SDB on blood pressure. We conducted the present study to evaluate the relationship between SDB and hypertension adjusting for sleep duration and shift work in a sample of Japanese steel workers. In this cross-sectional study, we measured blood pressure and oxygen desaturations index (ODI) by nocturnal pulse oximetry of 249 male workers aged 20 to 65 yr. SDB was defined by 3%ODI level of 15 or more events per hour. Logistic regression analyses were performed to estimate the associations of SDB with hypertension after adjustment for age, body mass index, alcohol intake, smoking, usual sleep duration, shift work, and occupation. The prevalence of SDB was 18.1%. The adjusted odds ratio of hypertension for high (> or =15) vs. low (<15) category of 3%ODI level was 2.86 (95% confidence interval, 1.23-6.66). The significant association between SDB and hypertension suggests that screening for SDB among steel workers is useful for prevention of hypertension.

Effort-reward imbalance and social support are associated with chronic fatigue among medical residents in Japan.

The purpose of this study was to determine the associations of effort-reward imbalance and social support with chronic fatigue among medical residents in Japan. A total of 104 men and 42 women at 14 teaching hospitals participated in this study. Chronic fatigue was measured by the checklist individual strength questionnaire. Effort, reward and overcommitment were determined by the effort-reward questionnaire developed by Siegrist. Social support was determined by a visual analog scale. Sleeping hours for the last 30 days were estimated based on the number of overnight shifts worked, the average number of sleeping hours, and the number of hours of napping during overnight work. Multiple regression analysis was used to examine the multivariate relationship between these variables and chronic fatigue. In both men and women, effort-reward imbalance was positively associated, and higher social support was negatively associated with chronic fatigue. In men, higher overcommitment was positively associated with chronic fatigue. In women, longer sleeping hours was negatively associated with chronic fatigue and an interaction between sleeping hours and social support was found. The adjusted variance in fatigue explained by the exposure variables was 34% in men and 51% in women. The result of this study suggested that it is desirable to take these factors into consideration in the management of chronic fatigue among medical residents.

Associations of excessive sleepiness on duty with sleeping hours and number of days of overnight work among medical residents in Japan.

Despite long-standing concerns regarding the effects of working hours on the performance and health of medical residents, and the patients' safety, prior studies have not shown an association of excessive sleepiness with the number of sleeping hours and days of overnight work among medical residents. In August 2005, a questionnaire was mailed to 227 eligible participants at 16 teaching hospitals. The total number of sleeping hours in the last 30 d was estimated from the average number of sleeping hours during regular days and during days with overnight work, and the number of days of overnight work. Multiple logistic regression analysis was used to adjust for potentially associated variables. A total of 149 men and 47 women participated in this study. The participation rate was 86.3%. Among the participants, 55 (28.1%) suffered from excessive sleepiness. Excessive sleepiness was associated with sleeping for less than 150 h in the last 30 d (corrected odds ratio [cOR]=1.57; 95% confidence interval [CI], 1.02-2.16). The number of days of overnight work in the last 30 d showed no association with excessive sleepiness. Excessive sleepiness was also associated with smoking (cOR, 1.65; 95%CI, 1.01-2.32). Medical residents who slept for less than 150 h in the last 30 d and smoked had a significantly higher risk of excessive sleepiness on duty.

Association between job stressors and heavy drinking: age differences in male Japanese workers.

The objective of the present study is to investigate the association between various occupational stressors and heavy drinking among male Japanese workers in different age groups. Using the Generic Job Stress Questionnaire, 13 occupational stressors and 2 workplace support indicators were assessed. The questionnaire survey was conducted of 25,104 workers, and the present study analyzed the data from 17,501 male workers. Heavy drinking was defined as weekly alcohol consumption of >275 g, and a total of 1,131 men (6.5%) were classified as heavy drinkers. After adjusting for shift work, occupational class, marital status and smoking, heavy drinking was related to "support from supervisor" for the 18-29 and 50-72 yr-old groups. For the 30-39 yr-old group, heavy drinking was related to "intragroup conflict", "job control" and "cognitive demands." For the 40-49 yr-old group, heavy drinking was related to "physical environment", "quantitative workload" and "underutilization of abilities." The present study clarified that certain occupational stressors relate to heavy drinking, and that this association varies among different age groups.

Application of the stratum-specific likelihood ratio (SSLR) analysis to results of a depressive symptoms screening survey among Japanese workers.

BACKGROUND: The stratum-specific likelihood ratio (SSLR) has been widely used as a convenient method to interpret the results of screening surveys. In the present paper, an SSLR analysis is applied to the results of a survey that used the Center for Epidemiologic Studies Depression Scale (CES-D) to identify depressive symptoms in a group of Japanese workers in an attempt to determine score categories that have predictive clinical values in a screening context. METHODS: The self-reported CES-D and the Mini International Neuropsychiatric Interview (MINI) were administered to 2,219 workers (84.2% men; age 21-68 years) during a periodical medical examination. The SSLR was calculated to determine strata with optimal discrimination for major depressive disorder (MDD). RESULTS: For MDD, the SSLR was 0.06 (95%CI: 0.02-0.18) for the CES-D score range 0-16, 1.90 (0.78-4.62) for the score range 17-19, and 12.4 (10.2-15.1) for the score above 20. CONCLUSIONS: The SSLR shown in this study proposes score categories that guide clinicians in selecting the workers most at risks of having MDD among Japanese workers.

Validity of the Center for Epidemiologic Studies Depression Scale as a screening instrument of major depressive disorder among Japanese workers.

BACKGROUND: The Center for Epidemiologic Studies Depression Scale (CES-D) is used at workplaces to screen depressive disorders. The aim of this study was to examine the validity of the CES-D for depression in a workplace. METHODS: The CES-D was administered to 2,219 workers (84.2% men; age 21-68 years) at a manufacturing company in Japan. Concomitantly all workers had an interview with the Mini International Neuropsychiatric Interview (MINI) as a gold standard for diagnosing major depressive disorder (MDD). The validity was evaluated by a receiver operating characteristic (ROC) curve. RESULTS: The area under the ROC curve of the CES-D was 0.96 [95% Confidence Interval (CI): 0.94-0.99]. The optimal cut-off score of MDD was 19 for screening. CONCLUSIONS: The validity of CES-D is confirmed and it is a valid instrument for detecting MDD in working populations in Japan.

Prospective studies on mental status and quality of life in patients with head and neck cancer treated by radiation.

Factors affecting the quality of life (QOL) in patients undergoing radiation therapy for head and neck cancer were determined in a prospective study. Full psychiatric interviews and self-report questionnaires concerning patients' QOL, pain, anxiety, mood, coping style and personality were administered to 35 patients with Stage I or II head and neck cancer before radiation therapy (week 0), and approximately one month (week 4) and two months (week 8) after starting of radiation. Anxiety, depression and pain were more severe at week 4 than at baseline. Anxiety was less at week 8, but depressive symptoms remained remarkable. Stepwise regression analyses revealed that changes in depressed mood and pain partially accounted for changes in disease-specific QOL. General health QOL related to a premorbid personality of openness and an emotional aspect of a coping style. Therapeutic interventions including psychiatric management of depression and physical management of pain appear to be crucial for preserving QOL during radiation treatment of patients with head and neck cancer.

Laterality of the performance of glaucoma mass screening using frequency-doubling technology.

PURPOSE: This study investigated laterality during the performance of glaucoma mass screening with a frequency-doubling technology perimetry test. MATERIALS AND METHODS: A frequency-doubling technology screening mode (C-20-1, version 2.6) test was performed on both eyes of 14,784 persons. Subjects with visual field abnormalities detected by the frequency-doubling technology test or with fixation error underwent retesting without a specified interval for rest. Consequently, 206 subjects who fulfilled the screening criteria of the frequency-doubling technology-based glaucoma screening protocol [FDT-GSP(+)] were further investigated using the Humphrey visual field analyzer (30-2). As a result, 74 right eyes and 57 left eyes were shown to have definite glaucoma. RESULTS: Frequency-doubling technology data for the left eye demonstrated a significantly (P<0.001) higher rate of artifacts, such as no reproducibility of results between the first and second tests (left/right: 2.4%/1.7%) as well as fixation errors (left/right: 2.8%/1.0%). The false-positive rate of the FDT-GSP for glaucoma was more than 1.5-fold higher in the left eye than in the right eye (16.3%/9.8%). In the case that either eye exhibited FDT-GSP(+), the positive predictive value of the FDT-GSP for definite glaucoma in the left eye was almost half of that in the right eye (28.4% vs. 53.8%). Specificity of the FDT-GSP for detection of definite glaucoma also exhibited a lower trend (P = 0.097) in the left eye (44.6%) than in the right eye (55.3%), but the sensitivity of the test was similar in both eyes (91.2% vs. 90.5%, respectively). CONCLUSIONS: When frequency-doubling technology-based mass screening is performed on the general population, performance is lower for the left eye than for the right eye. This performance disparity is likely to be primarily associated with a difference in specificity.