Yoneatsu Osaki

The association between use of mobile phones after lights out and sleep disturbances among Japanese adolescents: a nationwide cross-sectional survey.

STUDY OBJECTIVE The objective of this study was to examine the association between the use of mobile phones after lights out and sleep disturbances among Japanese adolescents. DESIGN AND SETTING This study was designed as a cross-sectional survey. The targets were students attending junior and senior high schools throughout Japan. Sample schools were selected by cluster sampling. Self-reported anonymous questionnaires were sent to schools for all students to fill out. PARTICIPANTS A total of 95,680 adolescents responded. The overall response rate was 62.9%, and 94,777 questionnaires were subjected to analysis. INTERVENTION N/A. MEASUREMENTS AND RESULTS Daily mobile phone use, even if only for a brief moment every day, was reported by 84.4%. Moreover, as for use of mobile phones after lights out, 8.3% reported using their mobile phone for calling every day and 17.6% reported using it for sending text messages every day. Multiple logistic regression analysis showed that mobile phone use for calling and for sending text messages after lights out was associated with sleep disturbances (short sleep duration, subjective poor sleep quality, excessive daytime sleepiness, and insomnia symptoms) independent of covariates and independent of each other. CONCLUSION This study showed that the use of mobile phones for calling and for sending text messages after lights out is associated with sleep disturbances among Japanese adolescents. However, there were some limitations, such as small effect sizes, in this study. More studies that examine the details of this association are necessary to establish strategies for sleep hygiene in the future.

Nightmare and sleep paralysis among Japanese adolescents: A nationwide representative survey

OBJECTIVE The objective of this study was to clarify the prevalence of nightmares and sleep paralysis and associated factors among Japanese adolescents. METHODS This study was designed as a cross-sectional sampling survey. The targets were junior and senior high schools throughout Japan. Self-reported anonymous questionnaires were sent to schools for all students to complete. RESULTS A total of 90,081 questionnaires were analyzed. The overall response rate was 62.6%, and the prevalence of nightmares and sleep paralysis was 35.2% and 8.3%, respectively. Multiple logistic analyses revealed that female sex, drinking alcohol, poor mental health, difficulty initiating sleep, low subjective sleep assessment, presence of excessive daytime sleepiness, and presence of sleep paralysis had higher odds ratios than others for nightmares. Male sex, poor mental health, drinking alcohol, taking a long daytime nap, early or late bedtime, difficulty initiating sleep, low subjective sleep assessment, presence of excessive daytime sleepiness, and presence of nightmares had higher odds ratios than other factors for sleep paralysis. CONCLUSIONS This study has revealed the prevalence of nightmares and sleep paralysis among Japanese adolescents. Furthermore, the results of this study suggest that it is important to maintain regular sleep habits for preventing these symptoms. We propose that health education about regular sleep habits should be promoted among Japanese adolescents.

Cigarette smoking among junior and senior high school students in Japan

PURPOSE To estimate the smoking prevalence among junior and senior high school students in Japan. METHODS We conducted a nationwide survey of adolescent smoking habits in 1990. Sample schools were selected by single random sampling. Self-administered anonymous questionnaires were sent to sample schools for all students to fill out. Seventy junior high schools and 33 senior high schools responded. A total of 57,189 students responded. RESULTS The current smoking rate (the proportion of students who had smoked at least once during the previous month) was much higher among boys than girls. The current smoking rate among seventh graders was 4.0% for boys and 1.5% for girls, and it increased with age to reach 25.5% for boys and 4.9% for girls in the twelfth grade. The percentage of regular smokers in the seventh grade was less than 1% for both sexes, but it increased to 20.3% for boys and 2.2% for girls in twelfth grade. Among current smokers, the proportion of boys smoking 1-9 cigarettes per day decreased, and the proportion of boys smoking 10 or more cigarettes per day increased, as age increased. Most current smokers buy their cigarettes from cigarette vending machines or tobacconist shops. CONCLUSIONS Since this survey reveals that smoking prevalence among students is not low even in junior high school, health education about smoking must start earlier and carry a greater emphasis within the curriculum. These results also indicate the importance of urging families to have greater concern for the smoking behavior of their children, of banning cigarette vending machines, and of preventing illegal sale of cigarettes to anyone under the age of 20 years.

Metabolic syndrome and incidence of liver and breast cancers in Japan

AIM OF THE STUDY To clarify the relationship between the presence of metabolic syndrome and the incidence of cancer in a general Japanese population. METHODS A retrospective cohort study was conducted among 8329 male and 15,386 female subjects between 1992 and 2000. The analysis used five definitions of metabolic syndrome. The information on the site-specific cancer was obtained from the population-based cancer registry. A Cox proportional hazard model was adapted for the statistical analyses. The average follow-up period was 9.1 years. RESULTS The National Cholesterol Education Program Adult Treatment Panel III 2001 criteria of metabolic syndrome revealed that the hazard ratio of metabolic syndrome for liver cancer was 1.89 (95% confidence interval (CI) 1.11-3.22) for males, and 3.67 (CI 1.78-7.57) for females. The hazard ratio for female breast cancer was 2.87 (CI 1.67-4.94). When the analysis was limited to postmenopausal women (55 years of age or older), the ratio increased to 6.73 (CI 2.93-15.43). The NCEP-ATPIII 2001 criteria were superior to the other four proposed criteria for predicting the incidence of cancer. In the statistical model, which included all components of the metabolic syndrome and the metabolic syndrome (present or absent), high blood glucose was a significant associated factor for all sites and liver cancers, whereas the metabolic syndrome was found to be a significant associated factor for breast cancer. CONCLUSION Metabolic syndrome may play an important role in the incidence of breast cancer. High fasting plasma glucose level is considered to be useful as an associated factor for the incidence of all-sites and liver cancer.

Adolescent smoking behaviour and cigarette brand preference in Japan

Objectives: As part of efforts to develop a smoking control strategy for Japanese adolescents, the results of two nationwide surveys on adolescent smoking behaviour were compared. Design: Descriptive study on smoking behaviour among high school students was conducted. Self-reporting anonymous questionnaires were administered to 115 814 students in 1996 and 106 297 in 2000 through randomly sampled junior and senior high schools throughout Japan. Main outcome measures: Smoking prevalence, proportion of smokers by usual sources of cigarettes, national estimated cigarettes consumed by minors, share of cigarette brands smoked by high school students. Results: The experiment rate among junior high school boys decreased in 2000 compared with that in 1996, whereas current and daily smoking rates did not. Although prevalence among Japanese girls was much lower than that among boys, prevalence among girls increased in 2000. The main source of cigarettes among high school smokers was vending machines. The proportion of smokers who usually purchased cigarettes from vending machines increased in 2000, in spite of the 1998 introduction of restrictions on night-time operations. Japanese adolescents were more likely than adults to smoke American cigarette brands, and the adolescent market share of American brands has increased rapidly, especially for menthol brands. Conclusions: This survey revealed the seriousness of the problem of smoking behaviour among Japanese high school students, and suggested that this behaviour may be influenced by social environmental factors, including the marketing strategies of the tobacco industry. Action should be taken to reduce the prevalence and impact of pro-tobacco marketing messages and to abolish cigarette vending machines.

Smoking prevalence of female nurses in the national hospitals of Japan

OBJECTIVE To estimate the prevalence of smoking and the attitudes towards the restriction of smoking at work among female nurses in the national hospitals in Japan. DESIGN Questionnaires mailed to 14 randomly selected national hospitals and sanitariums in Japan in 1993. SUBJECTS 2207 female nurses. MAIN OUTCOME MEASURES Smoking status and history, and attitudes towards the restriction of smoking at work. RESULTS The prevalence of smoking among female nurses was 18.6%, which was higher than the age-adjusted prevalence of the general female population using this study’s subjects as a standardised population. Banning smoking in the hospital in which they worked was supported by 15.0%, whereas 81.6% supported the restriction of smoking. CONCLUSIONS The results showed that smoking is more common among female nurses than among the general female adult population. The survey suggested that nurses favour restriction, but not banning, of smoking.

Sensitivity of endoscopic screening for gastric cancer by the incidence method

Although radiographic screening for gastric cancer has been conducted in Japan, it is anticipated that endoscopy will become a new screening method because of its high detection rate. The sensitivities of endoscopic and radiographic screening were calculated by the detection method and the incidence method based on the results of community‐based screening in Japan. There were 56,676 screenings for gastric cancer using endoscopy and radiography from April 2002 to March 2007 in Yonago, Japan. The target age group was from 40 to 79 years. Screen‐detected and interval cancers were investigated based on a screening database linked to the Tottori Cancer Registry. All gastric cancers diagnosed within 1 year after a negative screen were considered interval cancers. Based on the screening history, these were divided into prevalence screening and incidence screening. Prevalence screenings included 7,388 for endoscopic screening and 5,410 for radiographic screening, whereas incidence screenings included 18,021 for endoscopic screening and 11,417 for radiographic screening. The sensitivity of prevalence screening calculated by the incidence method was 0.886 (95% confidence interval [CI] = 0.698–0.976) for endoscopic screening and 0.831 (95% CI = 0.586–0.964) for radiographic screening; however, the difference was not significant (p = 0.626). The sensitivity of incidence screening calculated by the incidence method was 0.954 (95% CI = 0.842–0.994) for endoscopic screening and 0.855 (95% CI = 0.637–0.970) for radiographic screening (p = 0.177). Endoscopic screening for gastric cancer had a higher sensitivity than radiographic screening by the incidence method in both screening rounds. However, further study is needed to evaluate mortality reduction and to estimate overdiagnosis with endoscopic screening for gastric cancer.

Clarification of the factor structure of the 12-item General Health Questionnaire among Japanese adolescents and associated sleep status

If the factors affecting the mental health status of adolescents and their association with sleep status could be clarified, this information would be helpful for formulating lifestyle and healthcare guidance for the promotion of healthy growth and the prevention of mental problems in these individuals. The purpose of this study was to clarify (1) the factor structure of the 12-item General Health Questionnaire (GHQ-12), and (2) the associations between the factors extracted from this questionnaire and lifestyle, in particular sleep status, by using a representative sample population of Japanese adolescents. One hundred three thousand sixty hundred fifty self-administered questionnaires were collected from students enrolled in junior high and high schools in Japan. Of these questionnaires, 99,668 were analyzed. Sleep duration, subjective sleep assessment, bedtime, and insomnia symptoms of these students over the past month were studied to investigate sleep status. The factor analyses yielded two factors: depression/anxiety and loss of positive emotion. Sleep duration of less than 7h was found to be associated with both depression/anxiety and loss of positive emotion, whereas sleep duration of 8h or more was associated only with loss of positive emotion. Subjective sleep assessment and insomnia symptoms were associated with both depression/anxiety and loss of positive emotion. It was demonstrated that two underlying factors of mental health status were associated with differences in sleep status. In order to improve the mental health status of adolescents, it is important to provide guidance about sleep and lifestyle habits according to the mental health status of the individual.

Associations between sleep disturbance and alcohol drinking: A large-scale epidemiological study of adolescents in Japan

In this study, we attempted to clarify the associations between various sleep disturbance symptoms and the frequency and amount of alcohol use among Japanese adolescents. This study was designed as a cross-sectional sampling survey. A self-administered questionnaire survey was administered to students enrolled in randomly selected junior and senior high schools throughout Japan. A total of 99,416 adolescents responded, and 98,867 questionnaires were subjected to analysis. The prevalence rates of sleep disturbance in the 30 days preceding the day of the survey were as follows: subjectively insufficient sleep (SIS) (boys: 37.6%, girls: 38.7%); short sleep duration (SSD) with less than 6 h of sleep (boys: 28.0%, girls: 33.0%); difficulty initiating sleep (DIS) (boys: 12.5%, girls: 14.1%); difficulty maintaining sleep (DMS) (boys: 10.1%, girls: 10.9%); and early morning awakening (EMA) (boys: 5.1%, girls: 5.0%). Adolescents reporting one or more symptoms of DIS, DMS, and EMA were classified as having insomnia, and its prevalence was 21.5%. The prevalence of each symptom of sleep disturbance increased significantly with the number of days on which alcohol was consumed in the previous 30 days and the amount of alcohol consumed per drinking session (p < 0.01). Multiple logistic regression analyses showed that the adjusted odds ratio (AOR) for each symptom of sleep disturbance, except SIS and EMA, tended to increase with the number of days on which alcohol was consumed and the amount of alcohol consumed per drinking session. The prevalence of sleep disturbance is particularly high among adolescents drinking alcohol. The risk of having each symptom of sleep disturbance, except SIS and EMA, increases with the number of days on which alcohol was consumed and the amount of alcohol consumed per drinking session. These findings reconfirm the need to eliminate underage drinking to ensure good sleep among adolescents.

Decrease in the prevalence of smoking among Japanese adolescents and its possible causes: periodic nationwide cross-sectional surveys

AbstractObjectivesTo assess trends in smoking prevalence among Japanese adolescents and to analyze possible causal factors for the decrease in smoking prevalence observed in a 2004 survey.MethodsNationwide cross-sectional surveys were conducted in 1996, 2000 and 2004. Survey schools, both junior and senior high schools, considered to be representative of the whole of Japan were sampled randomly. Enrolled students were asked to complete a self-reporting anonymous questionnaire on smoking behavior. The questionnaires were collected from 115,814 students in 1996, 106,297 in 2000, and 102,451 in 2004. School principals were asked about the policy of their respective school on smoking restrictions.ResultsCigarette smoking prevalence (lifetime, current, and daily smoking) in 2004, based on the completed questionaires, had decreased relative to previous years in both sexes and in all school grades. The most important trends were: a decrease in smoking prevalence among the fathers and older brothers of the students; an increase in the proportion of students who did not have friends; a decrease in the proportion of current smokers who usually bought cigarettes in stores decreased in 2004, in particular for the oldest boys. An association was found between a lower smoking rate at a school and a smoke-free school policy.ConclusionsJapan has experienced a decrease in the prevalence of smoking among adolescents. A decrease in smoking prevalence among the fathers and older brothers, limitations to minors’ access to tobacco, an increase in the proportion of students without friends, and a school policy restricting smoking may have contributed to this decreasing trend.