Background Health and education are closely linked. However, few studies have explored the correlates of children’s academic performance in Japan. We aimed to investigate comprehensively the associations of low academic performance among school children with lifestyles, parental smoke, and socioeconomic status. Methods In 2016, children aged 6 to 13 years from the Super Diet Education School Project were surveyed using questionnaires. The survey explored the lifestyles and subjective academic performance of 1663 children and asked their parents about parental smoke and subjective socioeconomic status. Academic performance and socioeconomic status were divided into three levels. Then, we defined subjective academic performance in the lower two levels as low academic performance. The odds ratios (OR) were analyzed by logistic regression analysis. Results Among all participants, 299 (18.0%) children reported low academic performance. In general, low academic performance was significantly associated with late wakeup time (OR = 1.36 for 6:30 to < 7 a.m. and OR = 2.48 for ≥ 7 a.m.), screen time ≥ 2 h (OR = 1.35), studying at home < 1 h (OR = 1.82), paternal smoke (OR = 1.47), maternal smoke (OR = 1.87), and low socioeconomic status (OR = 1.48). Analyses stratified by grade showed stronger associations between academic performance and socioeconomic status in senior (OR = 1.62 for middle, OR = 1.52 for low in grades 4 to 6) than in junior children (OR = 1.15 for middle, OR = 1.38 for low in grades 1 to 3). Conclusions Children’s lifestyles, parental smoke, and socioeconomic status were significantly associated with low academic performance among Japanese children. Parents and health care providers should take these findings into consideration to prevent children from having low academic performance.

Background Individual lifestyle factors are associated with dental caries in children. The aim of this study was to investigate comprehensively the association between dental caries in elementary school children and lifestyle factors of the children and their parents. Methods Children from five elementary schools in Takaoka city, Toyama Prefecture, Japan (1,699: 848 boys, 851 girls, age range 6–12 years) participated in a survey conducted in March 2016. Questions on socioeconomic status (SES) and lifestyle factors in the children and their parents were included. Children who received treatment for three or more dental caries were defined as having many caries. Logistic regression analysis was performed to evaluate whether these factors were associated with the number of caries. Results The percentage of children with many caries (≥3) was 38.4%. In univariate analysis, being in 5th or 6th grade, frequent snacking, short sleep duration, long hours of media use, paternal smoking, and parental skipping of breakfast were significantly associated with many caries. Lack of affluence was marginally significant. In multivariate analysis, the association of short hours of sleep and long hours of media use remained significant. The adjusted odds ratio (OR) for media use of 1–2 h and more than 2 h were 1.79 (95% confidence interval [CI]: 1.30–2.46) and 2.24 (95% CI: 1.61–3.11) respectively. The adjusted OR for less than 8 h of sleep was 1.49 (95% CI: 1.07–2.06). Conclusions Long duration of media use and short duration of sleep were associated with dental caries. Establishing a healthy lifestyle is necessary for preventing dental caries in children.

BackgroundMolar incisor hypomineralization (MIH) frequently occurs in children worldwide. However, MIH prevalence throughout Japan has not yet been investigated. The purpose of this study was to clarify MIH prevalence rates and to consider potential regional differences throughout Japan.MethodsA total of 4496 children aged 7–9 years throughout Japan were evaluated in this study. MIH prevalence rates among children were evaluated in eight regions throughout Japan. A child’s residence was defined as the mother’s residence during pregnancy. The localization of demarcated opacities and enamel breakdown was recorded on a standard code form using a guided record chart. Logistic regression analysis was used to evaluate whether MIH prevalence rates differed among age groups, sex, and regions.ResultsThe overall prevalence of MIH in Japan was 19.8%. The prevalence of MIH was 14.0% in the Hokkaido region, 11.7% in the Tohoku region, 18.5% in the Kanto Shin-Etsu region, 19.3% in the Tokai Hokuriku region, 22.3% in the Kinki region, 19.8% in the Chugoku region, 28.1% in the Shikoku region, and 25.3% in the Kyushu region. These regional differences were statistically significant. Moreover, MIH prevalence rates decreased with age. No significant sex differences in MIH prevalence rates were demonstrated.ConclusionsTo our knowledge, this is the first MIH study carried out in several regions throughout Japan. Regional differences existed in MIH prevalence rates; particularly, MIH occurred more frequently in children residing in southwestern areas than those in northeastern areas of Japan.

Background: Little is known about pathological Internet use (PIU) and online risky behaviors among elementary school children. We aimed to investigate the prevalence and factors associated with PIU and online risky behaviors. Methods: A school-based cross-sectional study was conducted in Toyama, Japan in 2018. The study included 13,413 children in the 4th-6th grades (mean, 10.5 years old) from 110 elementary schools (61.1% of elementary schools in Toyama). We assessed PIU using Young's Diagnostic Questionnaire (YDQ) and risky behaviors. Poisson regression analysis was conducted. Results: Totally, 13,092 children returned questionnaires (response rate 97.6%). The prevalence of PIU was 4.2% and that of each risky behavior was as follows: 21.6% for spending money online, 6.6% for uploading personal movies, 5.2% for interpersonal issues, and 2.4% for having met strangers. PIU was significantly associated with boys (prevalence ratio [