Background: The increase in the number of Internet users has increased Internet dependence worldwide. In adolescents, this dependence may interfere with sleep, which is important for the development of psychophysiological capabilities. However, few large-scale surveys have described the relationship between Internet addiction (IA) and sleep disturbance using standardized questionnaires. We conducted a survey in one prefecture in Japan to determine the relationship between sleep disturbance and IA in adolescents based on the categories of the Young Diagnostic Questionnaire (YDQ).Methods: In 2016, high school students (N = 10,405, age range: 15–16 years) in all 54 daytime high schools in the selected prefecture were surveyed using a self-administered questionnaire. Participants with scores > 5.5 points on the Japanese version of the Pittsburgh Sleep Quality Index were defined as having a sleep disturbance. IA was evaluated using the YDQ: Participants with five to eight YDQ items present were classified as having IA; those with three or four items present were classified as “at risk of IA”; and those with two or less YDQ items were classified as “non-IA”. Multiple logistic regression analysis was performed with sleep disturbance as the dependent variable, IA as the explanatory variable, and adjustments for eight other variables.Results: High YDQ scores were associated with a high prevalence of sleep disturbance in boys and girls. These findings persisted after controlling for other factors in the multiple regression model.Conclusions: Among Japanese adolescents, there was a significant independent relationship between IA and sleep disturbance.

Study Objectives: Coping with stress is important because stress disturbs sleep. However, only a few longitudinal studies have investigated the association between coping and insomnia. We examined whether individuals with insomnia symptoms used more maladaptive coping strategies than individuals without insomnia symptoms, and evaluated the association between insomnia symptoms and coping strategies. Methods: In this prospective cohort study, Japanese workers were enrolled and observed over a 2-year period. During both years, self-administered questionnaires on coping and insomnia symptoms were administered. Coping was assessed using the Brief-Coping Orientation to Problems Experienced, and insomnia symptoms were examined using the Athens Insomnia Scale. Generalized estimating equation modeling identified the effects of coping strategies on insomnia severity. Results: In total, 1358 of 1855 workers at baseline were followed up. Individuals with insomnia symptoms showed a higher use of maladaptive coping strategies and less use of humor and instrumental support than individuals without insomnia symptoms. Active coping, humor, emotional support, and instrumental support were negatively associated with insomnia severity. In contrast, venting, substance use, behavioral disengagement, and self-blame were positively associated with insomnia severity. Conclusions: This study showed that individuals with insomnia symptoms use both adaptive and maladaptive coping strategies and are more likely to use maladaptive strategies than individuals without insomnia symptoms. In the future, interventions focused on educating people about adaptive coping strategies should be conducted to determine whether coping strategies may prevent insomnia symptoms.

Nonrestorative sleep (NRS) is a common sleep disorder. It is associated with several unhealthy lifestyle factors, such as skipping breakfast and lack of exercise. However, the associations between alcohol drinking, smoking, and NRS are unclear. This study examined the prevalence of NRS within the Japanese general population and the relationships among alcohol drinking, smoking, and NRS. We analyzed an anonymized dataset from a 2013 nationwide population survey (35,717 men and 39,911 women). NRS was assessed through a single-item question, and socio-demographic and lifestyle factors were assessed through self-reports. Multivariable logistic regression analyses were used to examine the associations between alcohol drinking, smoking, and NRS. The total prevalence of NRS was 22.2% (95% CI 21.8–22.7) in men and 23.4% (95% CI 23.0–23.8) in women. Further, we found that sleep duration and prevalence of NRS shared an inverse J-shaped relationship. Heavy alcohol drinking was significantly associated with NRS in both sexes. Short sleep duration and certain socioeconomic factors modified the effect of smoking on NRS in men. These results could be useful in the development of more effective sleep health policies to establish better sleep hygiene.

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.

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.