Children's screen time may affect their growth and development. However, different aspects of children and their parents that affect children's screen time has not been investigated in the Japanese context. This study aimed to explore the relationship between relevant factors affecting children's screen time based on their sleep, difficulties, and parental control, among Japanese elementary and junior high school students. A cross-sectional survey was conducted among parents in Japan. Data on screen time duration, parent-child background, strengths and difficulties, sleep variables, and parental control types were collected from 225 households. Path analysis revealed that high Strengths and Difficulties Questionnaire (SDQ) scores (β = 0.167, p = 0.007), sleep duration (β = -0.282, p < 0.001), and parental control (β = -0.205, p < 0.001) were significantly related to children's screen time. Additionally, late parental bedtime negatively correlated with children's sleep duration (β = -0.326, p < 0.001). The findings suggest that children's difficulties, sleep duration, and parental control are associated with children's screen time. This study, together with previous research, provides comprehensive insights to design interventions to decrease screen time in children in the Japanese context.

Studies reported adverse behavioral development including internalizing and externalizing problems in association with prenatal exposure to bisphenol A (BPA) and phthalates, however, findings were not sufficient due to using different assessment tools and child ages among studies. This study aimed to examine associations between maternal serum levels of BPA and phthalate metabolites and behavioral problems at preschool age. The Strengths and Difficulties Questionnaire (SDQ) was used to assess behavioral problems at 5 years of age. BPA and phthalate metabolite levels in the 1^st trimester maternal serum was determined by LC-MS/MS for 458 children. Variables used for adjustment were parental ages, maternal cotinine levels, family income during pregnancy, child sex, birth order and age at SDQ completed. The median concentrations of BPA, MnBP, MiBP, MEHP and MECPP were 0.062, 26.0, 7.0, 1.40, and 0.20 ng/ml, respectively. BPA level was associated with increased hyperactivity/inattention risk among girls (OR=1.66, 95% CI: 0.95-2.90) and∑DBP_m (MnBP + MiBP) level was associated with decreased total difficulties risk overall and among girls (OR=0.48, 95% CI: 0.20-1.13, OR=0.24, 95% CI: 0.06-1.03, respectively) without significance. MECPP level was associated with increase conduct problems risk (OR=2.78, 95% CI: 1.36-5.68). Our analyses found no significant association between BPA or summation of phthalate metabolite levels and any of the behavioral problems at 5 years of age, however, suggested possible association between MECPP levels and increased risk of conduct problems.