Yuuki Matsumoto

The 3-Dimensional Sleep Scale (3DSS) is used to assess sleep quality, quantity, and phase. However, its reliability and validity were established using classical methods and it has a small validation sample size. We aimed to increase the sample size and update the statistical methods to validate the reliability and validity of the 3DSS. We conducted a web-based survey of approximately 3000 day-shift workers at four companies in Tokyo, Japan, between 2021 and 2022. The 15 questions in the 3DSS were tested for reliability and validity according to the COSMIN checklist. The maximum likelihood method and promax rotation were selected for exploratory factor analysis. Reliability was tested by calculating the intraclass correlation coefficient and McDonald’s ω reliability coefficient. Convergent and discriminant validity were verified using multi-trait multi-method analysis. Cutoff values were verified using receiver operating characteristic curves and area under the curve (AUC). Existing measures used to validate the validity and cutoff values included the Athens Insomnia Scale, social jetlag, weekday sleep duration, and holiday waking time. Overall 2605 participants were included in the analysis after excluding non-responders, non-consenters, and absent employees. Exploratory factor analysis confirmed a three-factor structure for sleep phase, quality, and quantity. For convergent and discriminant validity, ideal correlations were observed for all subscales. The AUCs for sleep phase, sleep quality, and sleep quantity were 0.747, 0.812, and 0.819, respectively. The 3DSS offers sufficient reliability and validity as a sleep assessment scale. An English version of this scale should be developed in the future.

Few studies have examined the relationship between teleworking practices and presenteeism. This study determined the association between teleworking practices and presenteeism among teleworkers in Japan. A cross-sectional online survey was administered to 2687 teleworkers from five companies in Japan, collecting data on demographic variables, teleworking practices, frequency and duration of teleworking, presenteeism, and various lifestyle- and health-related factors. A logistic regression analysis was performed. Teleworkers with full-time employment and less teleworking experience exhibited higher presenteeism rates. Key practices negatively associated with presenteeism included creating a dedicated workspace, chatting with colleagues, and setting daily work goals. Gender differences were significant: for men, additional practices, such as determining their work hours, were beneficial; while for women, chatting with colleagues was particularly important. A sensitivity analysis indicated that specific teleworking practices can mitigate presenteeism. Certain teleworking practices, such as creating a workspace, chatting with colleagues, and setting work goals, were associated with lower presenteeism among teleworkers. These findings highlight the need for organizations to support telework ergonomics, promote social interaction, and encourage goal setting to enhance teleworker productivity and health. Training for employees and supervisors to raise awareness of their own and their subordinates’ health while teleworking is advised.

Background: The tobacco industry has actively advocated for electronic cigarettes (e-cigarettes) and heated tobacco products (HTPs) as harm-reduction alternatives to traditional cigarettes. Around 40% of smoking physicians have adopted HTPs. This study aimed to uncover the motivations behind Japanese physicians’ e-cigarette and HTP use while analyzing the associations between product use, physician demographics, lifestyles, and smoking preferences. Methods: A mail-based survey was conducted in 2020, targeting 6000 male and 1500 female physicians. From the 5492 survey participants, 346 physicians aged 28 to 98 who were current smokers were selected. The survey assessed their usage of e-cigarettes and HTPs and explored the reasons for initial adoption. A multivariate logistic regression analysis examined the relationships between product use, physician characteristics, and behaviors. Results: Approximately 33.8% of smoking physicians had experimented with e-cigarettes and HTPs. E-cigarette and HTP use correlated with youthfulness, nicotine addiction, and a history of medical treatment. The primary drivers for adopting e-cigarettes and HTPs were reduced odor (74.4%), perceived harm reduction (48.7%), and decreased exposure to secondhand smoke (29.1%). Conclusions: Physicians, when transitioning from conventional cigarettes to HTPs or e-cigarettes, are primarily motivated by a desire to reduce the odor of conventional cigarettes rather than health-related concerns.

Despite the serious influence of problematic Internet use on mental health among Japanese adolescents, no randomized clinical trials have investigated universal school-based interventions for this potential health challenge. Therefore, this study aimed to assess the efficacy of a school-based educational program. This two-armed, parallel, cluster-based randomized clinical trial included 5312 students from 13 high schools situated in a mid-sized Japanese city. The students in the intervention arm received 10 weekly standardized sessions, including a combination of information provision and interactive sessions by schoolteachers. The students in the control group followed a standard school curriculum. A generalized estimating equation model was applied to assess the primary (Korean Scale for Internet Addiction [K-scale] score) and secondary (behavioral change status according to changes in the transtheoretical model smartphone addiction score and Internet usage time) outcomes two months after intervention completion. The intention-to-treat analysis included 2597 (97.2%) and 2504 (94.9%) students in the intervention and control groups, respectively. Nevertheless, a significant discrepancy emerged regarding the behavioral change status. Therefore, this school-based program did not improve the Internet or smartphone addiction scores among Japanese adolescents. Further studies are needed to develop appropriate interventions for adolescents.

Social jetlag is associated with physical and mental health problems. With the increased popularity of telework, we investigated a specific form of social jetlag that we termed “telework jetlag”. This study aimed to clarify the relationship between telework jetlag—the difference in sleep and wake-up times between in-office and telework days—and mental health problems among Japanese hybrid workers. A cross-sectional study was conducted with 1789 participants from October to December 2021 using an online-based questionnaire. Telework jetlag, defined as the difference in the midsleep point between in-office and telework days, was investigated using two groups according to telework jetlag—those lagging <1 h versus ≥1 h. We used the six-item Kessler Scale as a nonspecific psychological distress scale for the outcome. Telework jetlag was significantly associated with psychological distress, and the ≥1 h group had a higher risk (odds ratio: 1.80) of developing high psychological distress (HPD) than the <1 h group in the multivariate analysis. Since most teleworkers are forced to have a hybrid work style that mixes going to work and teleworking, telework jetlag must be addressed to maintain the health of teleworkers.

Objectives: This study aimed to determine that workers’ sleep and labor productivity differ with the telework frequency and that the optimal telework frequency depends on workers’ psychological distress. Methods: A cross-sectional study using an online-based questionnaire was conducted with 2,971 workers employed by Japanese companies from October to December 2021. We used the 6-item Kessler Scale, K6, as a nonspecific psychological distress scale to screen mental health conditions. A score of ≤ 4 was defined as low psychological distress (LPD), and a score of ≥ 5 was defined as high psychological distress (HPD). We used the Athens Insomnia Scale (AIS) as a measure of sleep quality. The Utrecht Work Engagement (UWES) and Work Functioning Impairment (WFun) scales were used as measures of labor productivity. Series of analysis of covariance (ANCOVA) was used for the data analysis. Results: The analysis included 2,013 participants (1,390 men and 623 women; mean age 43.2 years, standard deviation 11.3). Multiple comparison tests showed that among the participants categorized HPD (HPD type), the AIS estimates were lowest in the 1–2 d/wk group, with significant differences between the 0–3 d/m and ≥ 5 d/wk groups. UWES estimates were lowest in the 3–4 d/wk group with significant differences between the participants categorized LPD (LPD type) and HPD type, while no significant differences were observed among the LPD type. The WFun estimates among the LPD type decreased significantly with increasing telework frequency, while no significant differences were observed among the HPD type. Conclusions: The optimal telework frequency for sleep and labor productivity may depend on the workers’ psychological distress. The finding of this study could make a great contribution to occupational health activities and health promotion for teleworkers, which is necessary to make teleworking a sustainable work style.

The objective of this study was to verify whether the assessment of poor sleep based on two sleep scales could predict suicidal ideation in Japanese dayworkers. A longitudinal survey was conducted among 446 Japanese dayworkers working at a company in Japan. Questionnaires were administered in 2013 (baseline) and 2014 (follow-up). To evaluate suicidal ideation, we used Question 19 of the Self-rating Depression Scale, categorizing participants who chose response options “some/a good part/most of the time” as suicidal ideation (+), and those who chose option “never or only a little of the time” as suicidal ideation (−). Two sleep scales, the Pittsburgh Sleep Quality Index (PSQI) and the 3-Dimensional Sleep Scale (3DSS), were selected as potential predictors of suicidal ideation. Only participants who were suicidal ideation (−) at baseline were included in the analysis, and suicidal ideation (+) individuals at follow-up were considered to have developed suicidal ideation during the interval between baseline and follow-up surveys. Data from 293 participants (236 men, 57 women) were analyzed. Twenty-two participants (7.5%) became suicidal ideation (+) at follow-up. Multiple logistic regression analysis showed that only sleep quality of the 3DSS subscale significantly predicted suicidal ideation, even after adjusting for depressive symptoms. That is, assessment of poor sleep did not predict suicidal ideation when based on the PSQI, but did when based on the 3DSS. Assessment of sleep quality based on the 3DSS may prove more useful in predicting worker suicidal ideation in industrial settings with limited facilities than PSQI.

Unmarried people often have disorderly lifestyles, and sleep problems (e.g., insomnia, short sleep duration, social jetlag) are becoming more complex due to the modern 24-h society. To improve health promotion measures for unmarried people, this study examined the relationship between marital status and sleep assessed as a multifactorial structure (phase, quality, quantity) in Japanese day workers. A cross-sectional survey was conducted with employees at five workplaces in Japan. Participants indicated their marital status, and the 3-Dimensional Sleep Scale measured sleep condition. We used scale cutoff values to define poor sleep phase, quality, and quantity (scores below the cutoff). “All poor sleep” and “all good sleep” were defined as when all scores were below or above the cutoff, respectively. Data from 786 participants (578 men, 208 women) were analyzed. Multivariate analysis showed that being unmarried was significantly related to poor sleep phase, quality, and quantity, with increased odds ratios. In unmarried participants, odds ratios (OR) were highest for poor sleep quantity in men (OR: 2.15) and poor sleep phase in women (OR: 2.73). All poor sleep showed the highest odds ratio for both unmarried men (OR: 2.74) and women (OR: 6.13), while unmarried men showed significantly decreased odds ratios for all good sleep (OR: 0.51). The finding that being unmarried was more closely associated with poor sleep quality and quantity in men, and more closely associated with poor sleep phase in women, could greatly contribute to creating measures to promote improved sleep in unmarried people.

To clarify the predictors of poor sleep quality in Japanese adolescents. In 2010, baseline surveys were administered to students at 24 randomly selected schools—10 junior high schools and 14 senior high schools—in Japan. After 2 years, follow-up surveys were administered to the same students. The questionnaires included the following five items: basic attributes, sleep status, lifestyle factors, social relationships, and mental health status. Only participants without “poor sleep quality” at baseline were included for analyses and the incidence proportion of poor sleep quality was calculated by observing the rate of poor sleep quality at follow-up. A total of 3473 students were included for analysis. During the 2 years leading to the follow-up study, the incidence proportion of poor sleep quality was 7.7% among junior high and 6.9% among senior high school students. Multivariate analyses revealed that factors associated with poor sleep quality were poor mental health, no extracurricular learning, and short sleep duration on weekdays in junior high school students and poor mental health, waking up at 7:00 or later on weekdays and short sleep duration on weekdays in senior high school students. In junior high school students, mental health status, extracurricular learning, and sleep duration could be predictors of poor sleep quality, whereas in senior high school students, mental health status, waking time, and sleep duration on weekdays could be predictors. The present findings suggest that sleep health should be promoted among junior and senior high school students.