Factors Associated with the Development of Childhood Asthma in Japan: A Nationwide Longitudinal Study.

INTRODUCTION: Many environmental factors are related to the development of asthma. However, the key factors of childhood asthma onset have not been sufficiently elucidated. Further, low-weight births have increased in Japan. The aim of this study was to examine the risk factors for the incidence of childhood asthma and to evaluate whether these risk factors differ according to birth weight in Japan. METHODS: We used the National Longitudinal Survey from 2001 to 2010. Multiple logistic regression analyses were conducted to determine the effects of gender, birth weight, single vs. multiple births, birth order, nutrition, keeping pets in the home, place of residence, annual household income, and parent ages, smoking behaviors, and educational backgrounds on asthma-related hospital visits. RESULTS: Overall, 45,060 children were analyzed. The rate of cumulative hospital visits until age 10 was 18.9%. Birth weight < 2500 g (adjusted odds ratio [AOR] = 1.14, 95% confidence interval [CI] 1.03-1.26), being a boy (AOR = 1.27, 95% CI 1.21-1.33), having older siblings (AOR = 1.07, 95% CI 1.02-1.14), parental smoking behavior, mother`s age, and low household income (AOR = 1.17, 95% CI 1.10-1.24) were associated with asthma-related hospital visits. DISCUSSION: Parental smoking behavior is a key risk factor for the development of asthma. Among low birth weight infants, being a boy, having older siblings, and father`s smoking behavior were predictive factors for the development of asthma. However, low birth weight was not associated with the development of asthma after 6 years of age.

The association between alcohol use and problematic internet use: A large-scale nationwide cross-sectional study of adolescents in Japan.

BACKGROUND: This study aimed to clarify the associations between the frequency and amount of alcohol consumption and problematic Internet use, such as Internet addiction and excessive Internet use. METHODS: A self-administered questionnaire survey was administered to students enrolled in randomly selected junior and senior high schools throughout Japan, and responses from 100,050 students (51,587 males and 48,463 females) were obtained. Multiple logistic regression analyses were performed in order to examine the associations between alcohol use and problematic Internet, use such as Internet addiction (Young Diagnostic Questionnaire for Internet Addiction ≥5) and excessive Internet use (≥5 h/day). RESULTS: The results of multiple logistic regression analyses indicated that the adjusted odds ratios for Internet addiction (YDQ ≥5) and excessive Internet use (≥5 h/day) became higher as the number of days in which alcohol had been consumed during the previous 30 days increased. In addition, the adjusted odds ratio for excessive Internet use (≥5 h/day) indicated a dose-dependent association with the amount of alcohol consumed per session. CONCLUSIONS: This study revealed that adolescents showing problematic Internet use consumed alcohol more frequently and consumed a greater amount of alcohol than those without problematic Internet use. These findings suggest a close association between drinking and problematic Internet use among Japanese adolescents.

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.

A Nationwide Cohort Study of Parasomnias Among Adolescents.

Objective: To elucidate the incidence rates and predictive factors for parasomnias (disorders of arousal, nightmare, and sleep paralysis) in adolescents.Methods: This was a prospective cohort study of high school students. In 2010, we conducted a baseline survey of first-year students enrolled in randomly selected Japanese schools (10 junior high schools and 14 senior high schools); 2 years later, a follow-up survey of the same participants was conducted. A self-administered questionnaire inquiring about parasomnias and lifestyles was provided to the students for both surveys. The incidence of new onset of each parasomnia was determined based on the longitudinal survey data obtained at 2 timepoints (ie, baseline and follow-up), separately for the junior and senior high-school students. Moreover, we performed multivariate analyses to identify the predictive factors for new onset of each parasomnia.Results: 776 junior high school students and 2,697 senior high school students participated in both surveys (total response rate: 61.1%). The incidence rates of disorders of arousal, nightmares, and sleep paralysis during the observation period were 14.0%, 16.2%, and 3.3%, respectively, among junior high school students, and 15.1%, 27.8%, and 6.8%, respectively, among senior high school students. The predictive factors (adjusted odds ratio, P value) for new onset of disorders of arousal were female sex (1.38, .009) and sleep duration of less than 5 hours (1.95, .001). The predictive factors for onset of nightmares were female sex (1.82, < .001), enrollment in senior high school (vs junior high school) (2.14, < .001), poor subjective sleep quality (1.60, .010), and spending less than 2 hours studying after school hours (1.64, .027). The predictive factors for new onset of sleep paralysis were enrollment in senior high school (vs junior high school) (2.39, .002) and poor mental health status (1.98, < .001).Conclusions: Our study results suggest that sleep status, lifestyle, and mental health are predictive factors for new onset of parasomnias in adolescents. These should be key areas of focus in school health services.

A nationwide cross-sectional study of difficulty waking up for school among adolescents.

STUDY OBJECTIVES: To determine the prevalence of and risk-factors for difficulty waking up for school among adolescents. METHODS: We used a self-administered questionnaire (140 junior high schools [JHSs]; 124 senior high schools [SHSs]) selected randomly in 2012 from throughout Japan. RESULTS: Total response rate: 60.7%. Data from 38 494 JHS and 61 556 SHS students were analyzed. The prevalence of at least one instance of school tardiness/absence due to difficulty waking up over a 30-day period was 10.9 (95% confidence-interval:10.5-11.3)%/2.9(2.7-3.1)% for JHS-boys and 7.7(7.3-8.1)%/2.0(1.8-2.2)% for JHS-girls. The prevalence was 15.5(15.1-15.9)%/5.6(5.3-5.9)% for SHS-boys and 14.4(14.0-14.8)%/5.9(5.6-6.2)% for SHS-girls. We used ordinal regression to identify the risk factors associated with the experience of school tardiness/absence. Factors significantly associated with school tardiness in all four groups (JHS boys/girls, SHS boys/girls) were "no-participation-in-club-activities," "early-morning-awakening," "feeling bad throughout a morning," "drinking," and "smoking." Among associated factors, the highest odds ratio was found for monthly smoking-days (none vs. at least one-day or more) for JHS-girls at 5.30(3.57-7.85). Factors significantly associated with school absence in all four groups were "no wishing to go to university," "no participation in club activities," "disorders of initiating and maintaining sleep," "long internet use," "drinking," "smoking," "poor-mental-health" and "feeling bad throughout a morning." Among associated factors, the highest odds ratio was found for monthly smoking-days (none vs. at least one-day or more) for JHS-girls at 4.60(3.45-6.15). CONCLUSIONS: These results suggest that the risk factors for difficulty waking up among adolescents are sleep status, lifestyle, and mental health, which can indicate the presence of an underlying disease.

Psychometric Properties of a New Simplified Scale to Assess the Quality of Workers' Rest and Recreation on Their Days Off.

BACKGROUND: In this study, we developed and tested the validity and reliability of the 12-item Rest and Recreation Quality Scale (RRQ-Scale) for Workers as a new scale capable of conveniently assessing the quality of workers' days off, that is, their rest and recreation. METHODS: Participants included 756 employees (694 men, 62 women, mean age ± SD= 44.7 ± 13.5, age range = 18-81) of 26 manufacturing-related companies located in Oita Prefecture, Japan. We analyzed the factorial validity of the scale's score distribution and its criterion-related validity and reliability (Cronbach's coefficient α), compared to MOS 36-Item Short-Form Health Survey version 2.0 (SF-36v2) and the generalized self-efficacy scale. Participants responded to the 12 questions on 4-point scales; these were summed to calculate the total score (score range: 12-48 points). RESULTS: The smallest and largest mean ± SD of the questions were 2.53 ± 0.89 and 3.21 ± 0.74, respectively, which are within the possible score range (1-4, implying the absence of floor and ceiling effects). A confirmatory factor analysis indicated that the goodness of fit of the higher-order factor analysis model was satisfactory (GFI = 0.955), confirming factorial validity. In addition, consistent with the theoretical predictions, the total score exhibited statistically significant positive correlations with the components of the SF-36v2; physical component summary (PCS): rs = 0.193, P < 0.001, mental component summary (MCS): rs = 0.369, P < 0.001, and role/social Component Summary (RCS): rs = 0.115, P = 0.002. This confirmed criterion-related validity. Further, the overall reliability of the scale was high; α = 0.877. CONCLUSION: In sum, the score distribution, validity, and reliability of the RRQ-Scale for workers were good, indicating a high degree of practicality.

Risk Factors at Birth Predictive of Subsequent Injury Among Japanese Preschool Children: A Nationwide 5-Year Cohort Study.

OBJECTIVE: To identify risk factors at birth that are predictive of subsequent injury among preschool children. METHODS: Retrospective analysis of population-based birth cohort data from the "Longitudinal Survey of Babies Born in the 21st Century" was performed from 2001 through 2007 in Japan (n = 47,015). The cumulative incidence and the total number of hospitalizations or examinations conducted at medical facilities for injury among children from birth up to the age of 5 years were calculated. To identify risk factors at birth that are predictive of injury, multivariate analysis of data for hospitalization or admission because of injury during a 5-year period (age, 0-5 years) was performed using the total number of hospital examinations as the dependent variable. RESULTS: The cumulative incidence (95% confidence interval) of hospital examinations for injury over the 5-year period was 34.8% (34.2%-35.4%) for boys and 27.6% (27.0%-28.2%) for girls. The predictive risk factors at birth we identified for injury among preschool children were sex (boys), heavy birth weight, late birth order, no cohabitation with the grandfather or grandmother, father's long working hours, mother's high education level, and strong intensity of parenting anxiety. CONCLUSION: Based on the results of this study, we identified a number of predictive factors for injury in children. To reduce the risk of injury in the juvenile population as a whole, it is important to pursue a high-risk or population approach by focusing on the predictive factors we have identified.

Factors Related to Alcohol Consumption Among Japanese Physicians.

This study aimed to investigate the drinking habits of Japanese physicians, and clarify their causal factors. A self-administered questionnaire was sent to 6000 male and 1500 female physicians, selected from among members of the Japan Medical Association. We analyzed the correlation of drinking habits with age, medical department, smoking and exercise status, work environment, sleep problems, and mental health. The response rate was 79.4%. Physicians with a heavy drinking habit were most frequently men in their 60s and women in their 20s to 50s. Drinking or heavy drinking tendencies decreased with increasing age. Smoking status was correlated with heavy drinking. Exercise status was correlated with drinking among men, and drinking/heavy drinking among women. Mental health was not correlated with drinking habit. However, sleep problems were correlated with a heavy drinking habit. These results suggest that countermeasures need to be taken to decrease the rate of heavy drinking among physicians.

Longitudinal Epidemiologic Study of Poor Mental Health Status in Japanese Adolescents: Incidence of Predictive Lifestyle Factors.

OBJECTIVE: To clarify the incidence of predictive risk factors for poor mental health status in Japanese adolescents. METHODS: In 2010, baseline surveys of first-year junior and senior high school students were conducted at 10 randomly selected junior high schools and 14 senior high schools in Japan. After 2 years, follow-up surveys were conducted on the same students. For both surveys, a self-administered questionnaire about mental health status and lifestyle, General Health Questionnaire-12 (GHQ-12), was provided to the students. RESULTS: In total, 1,304 junior and 4,383 senior high school students were enrolled at the start of the study, and 776 junior and 2,697 senior high school students responded to both surveys. The new incidence of poor mental health status (GHQ-12 ≥ 4 points), determined by changes between the baseline and follow-up surveys, was 17.1% (95% CI, 13.9% to 20.3%) of junior high school students and 22.6% (95% CI, 20.5% to 24.7%) of senior high school students. According to the multiple logistic regression analysis, in junior high school students, factors associated with the onset of poor mental health were not participating in sports activities (adjusted odds ratio, 3.13; P = .035) and spending ≥ 2 hours per day studying outside of school (2.18; P = .010). In senior high school students, factors associated with the onset of poor mental health were female sex (2.51; P < .001), difficulty initiating sleep (3.38; P < .001), poor sleep quality (1.83; P = .034), poor appetite (3.43; P = .011), spending less than 2 hours per day watching television (1.37; P = .038), being a victim of bullying (2.46; P = .011), and not having a sympathetic supporter (1.72; P = .006). CONCLUSIONS: The findings of this study are valuable for formulating approaches aimed at addressing adolescent mental health.

The association between sleep disturbance and second-hand smoke exposure: a large-scale, nationwide, cross-sectional study of adolescents in Japan.

OBJECTIVE: This study investigated the association between secondhand-smoke (SHS) exposure and sleep disturbance symptoms. METHODS: This study was a cross-sectional survey of junior and senior high school students throughout Japan. A total of 85,931 adolescents responded, and 84,988 questionnaires were included in the analysis. RESULTS: Adolescents who had never smoked accounted for 88.0% of respondents; among that group 39.1% reported having been exposed to SHS over the previous week. The results of multiple logistic regression analyses indicated that the adjusted odds ratios for insomnia symptoms such as difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS) and early morning awakening (EMA), as well as sleep disturbance symptoms such as subjectively insufficient sleep and short sleep duration (<6 h), tended to be higher both among never-smoking adolescents with SHS exposure and among smoking adolescents, as compared with never-smoking adolescents without SHS exposure. When adolescents with one or more of DIS, DMS, and EMA were defined as having insomnia, the adjusted odds ratio for insomnia was highest for adolescents who smoked, followed in descending order by those exposed to SHS both inside and outside the home, those exposed to SHS only inside the home, those exposed to SHS only outside the home, and never-smoking adolescents without SHS exposure (p < 0.001). CONCLUSIONS: The present study has revealed that SHS exposure is associated with sleep disturbance. Thus, in addition to smoking cessation programs, it is also necessary to endorse measures to protect adolescents from SHS exposure in order to promote good sleep in this population.

Relationship between stress coping and sleep disorders among the general Japanese population: a nationwide representative survey.

OBJECTIVE: To clarify the prevalence of stress, and examine the relationship between sleep disorders and stress coping strategies among highly stressed individuals in the general Japanese population. METHODS: A cross-sectional nationwide survey was undertaken in November 2007. Men and women were randomly selected from 300 districts throughout Japan. Data from 7671 (3532 men (average age 53.5 ± 17.0 years) and 4139 women (average age 53.9 ± 17.7 years)) were analyzed. Participants completed a self-reported questionnaire on stress, sleep disorders, and stress coping strategies in the previous month. RESULTS: Highly stressed individuals comprised 16.6% (95% confidence interval 15.8-17.5%) of the total sample, and most were aged 20-49 years. In multiple logistic regression, symptoms of insomnia (ie, difficulty initiating sleep, difficulty maintaining sleep, and early morning awakening), excessive daytime sleepiness, nightmares, daytime malfunction, and lack of rest due to sleep deprivation were more prone to occur in highly stressed individuals. In addition, logistic regression analysis controlling for other adjustment factors revealed that stress coping strategies such as 'giving up on problem-solving', 'enduring problems patiently', 'smoking' and 'drinking alcohol' were positively associated with the above-mentioned sleep disorders. On the other hand, stress coping strategies such as 'exercising', 'enjoying hobbies', and 'sharing worries' were inversely associated with the above-mentioned sleep disorders. CONCLUSIONS: Distraction-based stress coping (eg, hobbies, exercise, and optimistic thinking) was found to be preferable to problem-based stress coping in a highly stressed Japanese general population.

Short sleep duration, shift work, and actual days taken off work are predictive life-style risk factors for new-onset metabolic syndrome: a seven-year cohort study of 40,000 male workers.

BACKGROUND: This longitudinal study investigated the effects of various lifestyle-related factors - including sleep duration, shift work, and actual days taken off work - on new-onset metabolic syndrome (MetS). METHODS AND RESULTS: A total of 39,182 male employees (mean age 42.4 ± 9.8 years) of a local government organization in Japan were followed up for a maximum of seven years, between 1999 and 2006. Multivariate analysis (Cox proportional hazard method) identified seven high-risk lifestyle factors that were significantly associated with new-onset MetS or a range of metabolic factors (obesity, hypertension, hyperglycemia, dyslipidemia): (1) short sleep duration (<5 h/day), (2) shift work, (3) insufficient number of days off work, (4) always eating until satiety, (5) not trying to take every opportunity to walk, (6) alcohol intake ≥60 g/day, and (7) smoking. In addition, a higher number of these high-risk lifestyle factors significantly promoted the onset of MetS. The hazard ratio for MetS associated with 0-1 high-risk lifestyle parameters per subject at the baseline was set at 1.00. Hazard ratios associated with the following numbers of high-risk lifestyle parameters were: 1.22 (95% CI 1.15-1.29) for 2-3 of these parameters; and 1.43 (1.33-1.54) for 4-7. CONCLUSION: An increase in the number of high-risk lifestyle factors - such as short sleep duration, shift work, and an insufficient number of days off work - increased the risk of MetS onset. Comprehensive strategies to improve a range of lifestyle factors for workers, such as sleep duration and days off work, could reduce the risk of MetS onset.

Nationwide epidemiological study of insomnia in Japan.

BACKGROUND: This study was a nationwide epidemiological study of insomnia in Japan. It was conducted because very few studies on this topic have previously been performed for the general Japanese population. METHODS: An interview survey on symptoms of insomnia (difficulty initiating sleep, difficulty maintaining sleep with difficulty resuming sleep, and early morning awakening with difficulty resuming sleep) and daytime dysfunction was conducted on the general nationwide population in the winter (February) and summer (August) of 2008. Data from 2614 participants who provided valid responses (age range 20-95 years, valid response rate 54.2%) were analyzed. RESULTS: The prevalence of difficulty initiating sleep, difficulty maintaining sleep with difficulty resuming sleep, and early morning awakening with difficulty resuming sleep was 8.3%, 5.8%, and 5.8%, respectively, in men, and 11.0%, 8.1%, and 7.4%, respectively, in women. The prevalence of insomnia was 12.2% in men and 14.6% in women, and the prevalence of insomnia with daytime dysfunction was 3.2% in men and 4.2% in women. The results of logistic regression analyses indicated that the factors aggravating insomnia for men were unemployment and having mental health issues, and for women they were being aged ≥70 years, completing fewer years of schooling, and having mental health issues. Seasonality and regionality in association with insomnia were also examined, but no significant associations were found. CONCLUSION: In the present survey, insomnia was defined by using criteria that were closer to the clinical diagnostic criteria (eg, coexistence of both difficulty resuming sleep and daytime dysfunction was considered). Therefore, it is believed that the results of this study were representative of the clinical actuality of insomnia in Japan.

Association Between Smoking and Problematic Internet Use Among Japanese Adolescents: Large-Scale Nationwide Epidemiological Study.

The aim of this study was to clarify the association between smoking and problematic Internet use (PIU), such as Internet addiction (IA) and excessive Internet use (EIU), among Japanese adolescents. A self-administered questionnaire was administered to students enrolled in randomly selected junior and senior high schools throughout Japan. Responses were obtained from 100,050 students (0.94:1 ratio of boys to girls). The prevalence of IA (as indicated by a Young Diagnostic Questionnaire for Internet Addiction score ≥5) in all participants, boys, and girls was 8.1%, 6.4%, and 9.9%, respectively. The prevalence of EIU (≥5 hours/day) in all participants, boys, and girls was 12.6%, 12.3%, and 13.0%, respectively. The results of multiple logistic regression analyses indicated that the adjusted odds ratios (AORs) for IA and EIU were significantly higher among students who smoked (including those who previously smoked) than among those who never smoked (p < 0.01 for all comparisons). In addition, the AORs were the highest for students who smoked ≥21 cigarettes per day. The prevalence and AORs of IA and EIU tended to increase with smoking frequency and number of cigarettes smoked per day, indicating a dose-dependent relationship. Thus, IA and EIU have strong associations with smoking. This study revealed that adolescents who routinely smoked or those who smoked more cigarettes per day had a higher risk of PIU than adolescents who did not. These findings suggest that there is a close association between smoking and PIU among Japanese adolescents.

Anger and Impulsivity Among Japanese Adolescents: A Nationwide Representative Survey.

OBJECTIVE: This study aimed to clarify the prevalence of anger and impulsivity and its associated factors through a nationwide survey of junior and senior high school adolescent students in Japan. METHODS: A self-administered questionnaire covering (1) personal data, (2) lifestyle, (3) mental health status, and (4) feelings of anger and impulsivity was distributed to junior and senior high school students in Japan. Among the total of 10,955 junior high schools and 5,115 senior high schools nationwide, 130 and 110 were randomly selected, respectively. Of those, 92 junior and 80 senior high schools participated in the survey. The survey period was from December 2008 to the end of January 2009. A total of 95,680 questionnaires were collected. After excluding invalid responses, the remaining 94,777 responses (response rate: 62.3%) were analyzed. RESULTS: From the questions regarding anger and impulsivity, 8.7% (95% CI, 8.5%-8.9%) and 7.5% (95% CI, 7.3%-7.7%) of the participants were considered to have experienced intense anger and impulsivity, respectively. Logistic regression analysis indicated that the odds ratios for experiencing intense feelings of anger were significantly higher (all P values < .05) among students who smoked, consumed alcohol, skipped breakfast, did not wish to go to university, had short sleep duration, had decreased positive feelings, had increased depressive feelings, or used mobile phones for longer hours. The odds ratios for experiencing intense impulsivity were significantly higher among students who smoked, consumed alcohol, skipped breakfast, did not participate in club activities, had short sleep duration, had decreased positive feelings, had increased depressive feelings, or used mobile phones for longer hours. CONCLUSIONS: The results suggest that healthy lifestyle habits, good sleep habits, and improved mental health are important for preventing intense feelings of anger and impulsivity among adolescents.

Factors affecting unhappiness at school among Japanese adolescents: an epidemiological study.

BACKGROUND: Unhappiness at school is one of the main reasons for truancy among adolescents. In order to assess this problem more thoroughly in the context of Japanese adolescents, the present study examined the associations between feelings of unhappiness at school and lifestyle habits, school life realities, and mental health status. METHOD: This study was designed as a cross-sectional survey. A self-administered questionnaire was provided to students enrolled in randomly selected junior and senior high schools throughout Japan. We calculated the percentages of both junior and senior high school students who felt unhappy at school based on factors related to school life, lifestyle habits, and mental health status. Multiple logistic regression analyses were performed in order to examine the associations between those factors and students' feelings of unhappiness at school. RESULTS: A total of 98,867 valid responses were analysed, 7.9% (Boys: 8.4%, Girls: 7.4%) of which came from students who responded that they felt unhappy at school. For both junior and senior high school students, the percentages of those who felt unhappy at school were significantly higher among those who had not yet decided on their future life course, who did not participate in extracurricular activities, did not eat breakfast every day, went to bed late, had used tobacco or alcohol in the previous 30 days, and had poor mental health compared with others. The results of multiple logistic regression analyses indicated that the adjusted odds ratios for feeling unhappy at school with regard to the above-mentioned factors were significantly high for both junior and senior high school students. CONCLUSIONS: The present results suggest that school employees and administrators must provide health guidance to students, considering that irregular lifestyle habits, lower school engagement, smoking, drinking alcohol, and poor mental health status are all associated with maladaptation to school among adolescents.