Objective: To investigate the association between sleep duration and depressive symptoms in children and adolescents, so as to provide scientific evidence for promoting mental health and preventing depression among relevant populations. Methods: A total of 2 192 children and adolescents aged 10-17 years with complete data from the 2018 China Family Panel Studies Database were included. Eight item Center for Epidemiologic Studies Depressive Scale(CES-D8) was used to assess participants depressive levels, and sleep duration was assessed via questionnaire. Multivariate Logistic regression model was used to analyze the association between different sleep duration categories and depressive symptom occurrence among children and adolescents. A restricted cubic spline(RCS) model analyzed the dose response relationship between sleep duration and the risk of depressive symptoms occurrence and segmented Logistic regression models to identify dose response effects. Results: Among the surveyed children and adolescents, 524(23.91%) exhibited depressive symptoms. Compared to those with sufficient sleep, children aged 10-12 years had a higher risk of depressive symptoms on average per day( OR =1.66, 95% CI =1.19-2.33) and during weekdays( OR =1.76, 95% CI =1.26-2.46), as well as in adolescents aged 13-17 years on a daily basis( OR =1.40，95% CI =1.06-1.85) and during weekdays( OR = 1.48，95% CI =1.12-1.95), and excessive sleep in adolescents on rest days was also significantly associated with higher risk of depressive symptoms( OR =1.65，95% CI =1.11-2.43)(all P <0.05). RCS analysis results indicate that children s sleep duration exhibits a linear negative correlation with the risk of depressive symptoms(all P nonlinear >0.05), while adolescents sleep duration showed a U shaped association with depressive symptoms(all P nonlinear <0.05) on a daily basis, during weekdays and weekends, with potential threshold effects at 10.00, 9.88, and 9.60 hours, respectively. Conclusions Sleep duration among children and adolescents is associated with depressive symptoms, with notable age related differeneces. It is recommended to develop targeted age specific interventions to reduce the risk of depressive symptoms in children and adolescents.

Background The association between serum nickel (Ni) and oral cancer incidence is unclear and most of the previous studies were observational studies that did not control for confounding factors between groups. Objective To assess the correlation of serum Ni with oral cancer incidence based on propensity score matching (PSM) and inverse probability of treatment weighting (IPTW). Methods A cohort of 456 newly diagnosed oral cancer patients was recruited from the First Hospital of Fujian Medical University during November 2011 to May 2019, and residents ordered their health check-up in hospitals or local community health centers over the same period were selected as a control group, which included a total of 1410 participants. Serum Ni was evaluated by inductively coupled plasma mass spectrometry. Case-control pairs were selected using a 1:1 PSM (caliper value of 0.02), and the study subjects in the case group and control group were weighted for subsequent analysis by IPTW. The general characteristics of the study subjects were tested for equilibrium before and after matching by chi-square test and standardized mean difference (SMD). This was followed by exploring the potential nonlinear dose-response relationship between serum Ni and oral cancer using restricted cubic splines as well as analyzing the association between serum Ni and oral cancer incidence by conditional logistic regression and weighted logistic regression. Results After controlling for between-group covariates by PSM and IPTW, the dose-response curves demonstrated that the risk of developing oral cancer tended to decline and then increase with the increasing serum Ni level. The outcome of the analysis using PSM demonstrated that as compared to the control group, the risk of developing oral cancer in the 0.09-16.80 μg·L⁻¹ serum Ni group was negatively correlated with serum Ni level (OR=0.36, 95%CI: 0.24-0.54), whereas the risk of developing oral cancer in the >16.80 μg·L⁻¹ serum Ni group was positively correlated with serum Ni level (OR=5.43, 95%CI: 2.76-10.68). After applying IPTW, a negative association was found between the risk of oral cancer and serum Ni concentration within a serum Ni window ranging from 0.09 to 20.55 μg·L⁻¹ (OR=0.39, 95%CI: 0.29-0.52), while a positive association with an OR and 95%CI of 5.54 (3.62-8.49) for the Ni concentration > 20.55 μg·L⁻¹. Conclusion In this study, a J-shaped relationship between serum Ni concentration and the risk of developing oral cancer is found, which shows that high serum Ni concentration (>20.55 μg·L⁻¹) may be a risk factor for oral cancer.