Verification of sleep scales as predictors of suicidal ideation in Japanese dayworkers: a longitudinal study.

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. Supplementary Information: The online version contains supplementary material available at 10.1007/s41105-022-00404-6.

Longitudinal epidemiological study of subjective sleep quality in Japanese adolescents to investigate predictors of poor sleep quality.

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. Supplementary Information: The online version contains supplementary material available at 10.1007/s41105-021-00343-8.

A cross-sectional epidemiological study of the relationship between sleep duration, quality, and rhythm and presenteeism in workers.

This study aims to examine the relationship of sleep (sleep duration, sleep quality, and sleep rhythm) with presenteeism in workers while controlling for other confounding factors. A total of 2375 workers of six Japanese companies received self-administered questionnaires from June to November 2018. Information on sleep duration was used to evaluate sleep quantity, the Athens Insomnia Scale (AIS) was used to evaluate sleep quality, and workers' engagement in shift work was used to determine their sleep rhythms. We used the World Health Organization Health and Work Performance Questionnaire to evaluate presenteeism. Information on lifestyle (exercise, smoking, etc.), sex, and age was also collected. We conducted a logistic regression analysis with high absolute/relative presenteeism as an objective variable, sleep duration, AIS, and shift work as dependent variables, and basic attributes and lifestyle factors as adjustment factors. Completed questionnaires were collected from 1992 workers (aged 18-79 years; 25.2% women; response rate: 83.9%). Logistic regression analysis showed that high absolute presenteeism was significantly associated with poor sleep quality (high AIS score; P < 0.001) but not with sleep duration (P = 0.326) and shift work (P = 0.177). High relative absenteeism was significantly associated with poor sleep quality (high AIS score; P = 0.001) but not with sleep duration (P = 0.461) or shift work (P = 0.245). We showed that poor sleep quality is significantly associated with a high level of presenteeism. This suggests focusing on improving sleep quality is important for reducing presenteeism among workers.

The relationship between marital status and multifactorial sleep in Japanese day workers.

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. Supplementary Information: The online version contains supplementary material available at 10.1007/s41105-021-00357-2.