Both a higher suicide rate and widespread sleep problems are serious health concerns in Japan when compared with those of other countries. We investigated the relationship between suicidal ideation and sleep problems in Japanese day workers using the 3-dimensional sleep scale (3DSS), which measures three sleep elements (phase, quality, and quantity). Data from 635 Japanese day workers (461 mens and 174 womens) were included. The 3DSS was used to assess participants' sleep condition. Participants were classified into eight sleep types based on scores of phase, quality, and quantity: All Good Sleep, Owl (poor phase), Inefficient (poor quality), Short (poor quantity), Owl ? Inefficient (poor phase and quality), Owl ? Short (poor phase and quantity), Inefficient ? Short (poor quality and quantity), and All Poor Sleep. We assessed participants' suicidal ideation using question 19 of the selfrating depression scale (SDS); 119 cases (18.7 %) had ratings of 2-4 for this question and were considered to have suicidal ideation. The higher the number of sleep problems, the higher the risk of suicidal ideation compared to sleep types not indicative of problems. All Poor Sleep had the highest risk of the eight sleep types. Individuals with Owl ? Short, Inefficient ? Short, or All Poor Sleep had a significant risk of suicidal ideation even after adjusting for hopelessness and nightmares. Our findings suggested that sleep problems assessed by the 3DSS were related to suicidal ideation. Analysis of various aspects of sleep could be helpful for suicide prevention.

Numerous studies have determined that lifestyle factors (smoking, drinking, snacking, etc.) and the bedroom environment can influence sleep. We developed a new sleep scale—the 3-Dimensional Sleep Scale (3DSS)—which measures three elements of sleep: phase, quality, and quantity. The purpose of this study is to determine which risk factors of sleep complaints are associated with these sleep elements. Data were obtained from 366 Japanese day workers (302 men and 64 women). Sleep condition was assessed with the 3DSS, and we also assessed various habits within 2 h of going to bed, including smoking, drinking, snacking, caffeine intake, mobile phone use, and working. We also asked about bedroom environmental conditions (noise, lighting, and temperature and humidity). Multivariate logistic regression analysis using the backward selection method (likelihood ratio) was used, with 3DSS scores as the outcome (i.e., over or under the cutoff). The results showed that smoking was associated with significantly greater odds ratio [2.71 (1.65–4.44)] of disordered sleep phase, while lighting as well as temperature and humidity led to greater odds [3.67 (1.55–8.68), 1.93 (1.20–3.11)] of poor sleep quality. Finally, only noise was significantly related to greater odds [1.98 (1.13–3.46)] of low sleep quantity. These findings indicated the various risk factors of sleep complaints could be associated with different sleep elements. This might help in the effective treatment of sleep complaints.

Objectives This study aimed to evaluate students' subjective symptoms associated with exposure to low levels of formaldehyde (FA) during a gross anatomy course and to survey how the risk of subjective symptoms was affected by exposure to FA. Methods We conducted three questionnaire surveys of 125 students enrolled in an anatomy course (FA exposure group) and 124 students not enrolled in the course (FA nonexposure group) before, during, and 6 months after the course. The questionnaire included questions inquiring about subjective symptoms, sex, age, and allergies. We analyzed differences in the prevalence of subjective symptoms in distinct survey periods. Furthermore, we analyzed the relationship between the subjective symptoms and exposure to FA after adjusting for allergy, sex, and age using multiple logistic regression analysis. Results The prevalence of some of the ocular, nasal, and nonspecific symptoms in the FA exposure group was low before the course, increased during the course and decreased 6 months after the course. A significant positive relationship was observed between exposure to FA and some symptoms after adjusting for allergy, sex, and age. Conclusions We identified some concrete symptoms associated with exposure to FA. We suggest that the exposure to low levels of FA influences students' subjective symptoms.

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The aim of this study is to clarify factors that support the work engagement of nurses, who bear the burden of extended day shifts, by focusing on the advantages of the variable shift system and workday break activities. Methods: Nurses who were working under a variable shift system were asked to complete a self-report questionnaire to examine the workload, work engagement, work stressors, stress-coping strategies, and stress-coping break time activities, as well as the advantages and disadvantages of the variable shift system. Nine break activities were classified into the following four categories: social activities, rest/relaxation, entertainment, and cognitive activities. The advantages or disadvantages of the variable shift system were scored by developing composite variables using principal component analysis. These variables were used to perform a multiple regression analysis with work engagement as the dependent variable. Results: The advantage score was the variable most strongly correlated with work engagement. In contrast, "Quantitative workload" was negatively correlated with work engagement. Among break activities, in the social activities category correlations were observed in "Both conversation and Email/SNS" and "Conversation only". Although in fact most nurses chose conversation as one of the break options, more than half of the nurses selected rest/relaxation as their ideal break activity. Conclusion: Our study suggested that the variable shift system supported the work engagement of nurses who worked extended day shifts. The results also suggested that it would be useful to arrange the employee lounge environment so that employees could freely choose between "conversation" or "taking a rest" depending on the circumstances.