Abstract The prevention and control of myopia in Chinese children and adolescents has become a major public health issue. While maintaining increased outdoor activity as a cornerstone intervention, there is an urgent need to explore new complementary approaches that can be effectively implemented in both indoor and outdoor settings. In recent years, environmental spatial frequency has gained increasing attention as one of the key environmental factors influencing the development and progression of myopia. Both animal studies and human research have confirmed that indoor environments lacking mid to high spatial frequency components, often characterized as "visually impoverished", can promote axial elongation and myopia through mechanisms such as disruption of retinal neural signaling, impaired accommodative function, and altered expression of related molecules. Based on the scientific consensus, it is recommended that "enriching of environmental spatial frequency" should be integrated into the myopia prevention and control framework. Following the principles of schoolled organization, family cooperation, community involvement, and student participation, specific measures are put forward in three areas：optimizing school visual settings, improving home spatial environments, and promoting healthy visual behavior. The aim is to create "visually friendly" indoor environments as an important supplement to outdoor activity, thereby providing a novel perspective and strategy for comprehensively advancing myopia prevention and control among children and adolescents.

Objective: To compare the effects of height-desk-chair matching on the viewing distance of primary school students before and after intervention, so as to provide scientific basis for the hygiene management of desks and chairs. Methods: From April to June 2025, a random cluster sampling method was used to select 141 third grade students from three classes equipped with adjustable desks and chairs in a primary school in Hefei City for a height-desk-chair matching intervention study. The height of students desks and chairs was adjusted according to the standard height and height range specified in the Functional Sizes and Technical Requirements of Chairs and Tables for Educational Institutions (GB/T 3976-2014), with an intervention period of one week. Before and after the intervention, eye use data were measured by using the electronic smart device "Cloud Clip", while collecting data on vision data viewing distance, time spent using eyes at close range and outdoor time, desk and chair height, and physical examination. Linear regression analysis was used to investigate the factors related to viewing distance before the intervention of height-desk-chair matching, and a paired t-test was used to analyze the difference in viewing distance before and after the intervention. A mixed effects model was used to explore the effect of height desk and chair adaptation intervention on viewing distance. Results: The compliance rates for desk and chair adjustments before and after the intervention were 1.4% and 18.4%, respectively, with a statistically significant difference ( χ 2=22.84, P <0.01). The viewing distance increased from (30.48±5.01) cm before intervention to (32.06±5.75) cm post intervention, with a statistically significant difference ( t=4.57, P <0.01). The proportion of students meeting the viewing distance standard increased from 33.3% to 51.1%. The linear mixedeffects model results indicated that the association between height appropriate desk and chair interventions and viewing distance was statistically significant, regardless of whether covariates such as time spent using eyes at close range and outdoor time were adjusted ( β=-1.58, 95%CI = -2.25 to -0.91; β=-1.14, 95%CI =-1.85 to -0.43, both P <0.05). Conclusion Height adjusted desks and chairs, which can effectively increase the viewing distance for primary school students, has positive implications for improving healthy eye care behaviors among children and adolescents.

Multimorbidity of common diseases in children and adolescents refers to the coexistence of two or more common diseases or chronic health problems in the same individual. In recent years, the multimorbidity of common diseases in children and adolescents has become increasingly serious, which has enormously increased disease burden and socio-economic losses. These diseases typically share similar influencing factors, such as adverse environmental factors, unhealthy diets, lack of outdoor activities and physical exercise, sedentary lifestyle, excessive use of electronic devices, and disturbed sleep rhythms. Multidimensional interventions targeting these factors are effective methods of preventing and controlling multimorbidity of common diseases in children and adolescents. This review summarizes the public health burden, epidemiological data, risk factors, and interventions for multimorbidity of common diseases in children and adolescents to strengthen relevant research, develop effective intervention strategies, reduce the disease burden of children and adolescents, and promote their healthy growth.

Objective:To evaluate the association between pubertal timing and tempo with sleep duration in children.Methods:A total of 2 288 students from grade 1 to 3 were recruited from 3 primary schools in Bengbu, Anhui Province in 2013 by convenient sampling method, and a child health and development cohort was established and a baseline survey was conducted, followed by 4 follow-up surveys in 2015, 2017, 2018 and 2019. Each survey included a questionnaire survey, a physical examination and an assessment of pubertal development. Tanner stage of testicular volume in boys and breast development in girls were evaluated objectively by visual examination combined with palpation. The nonlinear growth model was used to evaluate the timing and tempo of puberty. After controlling confounding factors, generalized estimation equations were used to evaluate the association between pubertal timing and tempo and the 6-year sleep duration in children.Results:A total of 1 903 children with age of (8.10±0.87) years were enrolled, including 1 056 boys (55.50%). After adjusting for confounds, compared with children in normal timing group, children in early timing group had a decrease of 0.19 hours ( β=-0.19,95% CI:-0.30- -0.07, P=0.001) in sleep duration in 6 years, while children in late timing group had an increase of 0.14 hours ( β=0.14, 95% CI: 0.01-0.28, P=0.041) in sleep duration in 6 years. Compared with children in normal tempo group, children in slow tempo group had a decrease of 0.16 hours ( β=-0.16, 95% CI: -0.30- -0.02, P=0.021) in sleep duration in 6 years. Conclusions:Compared with children in normal timing group, the sleep duration of children in early timing group decreased, while the sleep duration of children in late timing group increased. Compared with normal tempo group, the sleep duration of the children in slow tempo group decreased.

Abstract In recent years, the prevalence of overweight and obesity among children and adolescents has risen rapidly, posing a serious threat to their physical and mental health. To provide scientific, systematic, and standardized weight management guidance for overweight and obese children and adolescents, the study focuses on the core concept of healthy lifestyle intervention, integrates multidisciplinary expert opinions and research findings,and proposes a comprehensive multidisciplinary intervention framework covering scientific exercise intervention, precise nutrition and diet, optimized sleep management, and standardized psychological support. It calls for the establishment of a multi agent collaborative management mechanism led by the government, implemented by families, fostered by schools, initiated by individuals, optimized by communities, reinforced by healthcare, and coordinated by multiple stakeholders. Emphasizing a child and adolescent centered approach, the consensus advocates for comprehensive, multi level, and personalized guidance strategies to promote the internalization and maintenance of a healthy lifestyle. It serves as a reference and provides recommendations for the effective prevention and control of overweight and obesity, and enhancing the health level of children and adolescents.

Objective: To explore the association between light at night (LAN) of different intensities and ocular biometric parameters among preschool children, so as to provide a reference for optimizing strategies for myopia prevention and control. Methods: From November 2024 to January 2025, a cross sectional study was conducted among 369 preschool children from one kindergarten in Quanzhou City, Fujian Province. Questionnaire survey and eye examination were performed, and portable light sensors were used to collect LAN exposure data. Spearman correlation analysis was used to examine the associations between the duration of LAN exposure at different intensities and ocular biometric parameters. Generalized linear model was employed to explore the relationships between LAN duration at various intensities and ocular biometric parameters, while restricted cubic spline was used to investigate potential nonlinear associations. Results: The spherical equivalent (SE), axial length (AL), and axial length/corneal radius of curvature (AL/CR) for preschool children were 0.38 (-0.13,0.63) diopters, 22.35 (21.86,22.88) mm, and 2.86 (2.82,2.90), respectively. The median daily duration (interquartile ranges) of LAN exposure at intensities of 0, >0-100, >100-300, and >300 lx were 6.09(5.31,6.74), 1.74(1.13,2.42), 0.06(0.00,0.26), 0.00(0.00,0.00)h/d, respectively. The generalized linear model showed that for every additional hour of LAN at >100-300 lx, the AL/CR increased by 0.26 (95% CI =0.01-0.52); for every additional hour of LAN at >300 lx, AL/CR increased by 0.32 (95% CI =0.05-0.59) (both P < 0.05). No statistically significant associations were observed between SE or AL and LAN exposure at any of the intensity levels (0, >0-100, >100-300, and >300 lx) (all P >0.05). The restricted cubic spline model revealed that, except for the nonlinear relationship between LAN duration and AL at >100-300 lx ( P =0.02), all other light intensity levels showed linear correlations between LAN duration and preschool children s SE, AL, and AL/CR (both P >0.05). Time of day subgroup analysis revealed that during school days, for every additional hour of LAN at >100-300 lx and over 300 lx，AL/CR increased by 0.18 (95% CI =0.01-0.35) and 0.22 (95% CI =0.03-0.41), respectively (both P <0.05). However, weekend exposure showed no statistically significant association (all P >0.05). Conclusion Higher intensity of LAN is associated with increased AL/CR, and reducing exposure to LAN may have a potential protective effect on the visual health of preschool children.

Objective:To evaluate the association between pubertal timing and tempo with sleep duration in children.Methods:A total of 2 288 students from grade 1 to 3 were recruited from 3 primary schools in Bengbu, Anhui Province in 2013 by convenient sampling method, and a child health and development cohort was established and a baseline survey was conducted, followed by 4 follow-up surveys in 2015, 2017, 2018 and 2019. Each survey included a questionnaire survey, a physical examination and an assessment of pubertal development. Tanner stage of testicular volume in boys and breast development in girls were evaluated objectively by visual examination combined with palpation. The nonlinear growth model was used to evaluate the timing and tempo of puberty. After controlling confounding factors, generalized estimation equations were used to evaluate the association between pubertal timing and tempo and the 6-year sleep duration in children.Results:A total of 1 903 children with age of (8.10±0.87) years were enrolled, including 1 056 boys (55.50%). After adjusting for confounds, compared with children in normal timing group, children in early timing group had a decrease of 0.19 hours ( β=-0.19,95% CI:-0.30- -0.07, P=0.001) in sleep duration in 6 years, while children in late timing group had an increase of 0.14 hours ( β=0.14, 95% CI: 0.01-0.28, P=0.041) in sleep duration in 6 years. Compared with children in normal tempo group, children in slow tempo group had a decrease of 0.16 hours ( β=-0.16, 95% CI: -0.30- -0.02, P=0.021) in sleep duration in 6 years. Conclusions:Compared with children in normal timing group, the sleep duration of children in early timing group decreased, while the sleep duration of children in late timing group increased. Compared with normal tempo group, the sleep duration of the children in slow tempo group decreased.

Multimorbidity of common diseases in children and adolescents refers to the coexistence of two or more common diseases or chronic health problems in the same individual. In recent years, the multimorbidity of common diseases in children and adolescents has become increasingly serious, which has enormously increased disease burden and socio-economic losses. These diseases typically share similar influencing factors, such as adverse environmental factors, unhealthy diets, lack of outdoor activities and physical exercise, sedentary lifestyle, excessive use of electronic devices, and disturbed sleep rhythms. Multidimensional interventions targeting these factors are effective methods of preventing and controlling multimorbidity of common diseases in children and adolescents. This review summarizes the public health burden, epidemiological data, risk factors, and interventions for multimorbidity of common diseases in children and adolescents to strengthen relevant research, develop effective intervention strategies, reduce the disease burden of children and adolescents, and promote their healthy growth.

Objective: To describe the prevalence and association of dietary rhythm and depressive symptoms among adolescents, so as to provide a basis for improving unhealthy behavioral habits,and to promote adolescent physical and mental health. Methods: From October to December 2021, a total of 22 868 students were selected from one middle school and high school in urban and rural areas of eight cities, namely, Shenyang, Xuzhou, Shenzhen, Taiyuan, Nanchang, Zhengzhou, Chongqing, and Kunming cities, China, using a combination of purposive sampling and stratified cluster random sampling. A self administered questionnaire was used to assess adolescents dietary rhythm, and the Patient Health Questionnaire-9 (PHQ-9) was used to assess depressive symptoms. Binary Logistic regression model was employed to analyze the associations between adolescent dietary rhythm and depressive symptoms, while the associations between adolescent dietary rhythm and depressive symptoms across gender and physical activity levels were stratified by gender and physical activity levels. Results: The detection rate of depressive symptoms in adolescents was 44.4%. The respective differences in the detection rates of depressive symptoms among adolescents of different genders, physical activity levels, and dietary rhythm disorders were statistically significant ( χ 2=157.51, 105.02, 3 282.50, P <0.01). Taking the low disordered dietary rhythm group as the reference, binary Logistic regression analyses showed that after adjusting for confounding factors such as age, gender，family location, family economic situation, whether only child, parental education level, and learning burden, physical activity levels, depressive symptoms were positively correlated with adolescents in the moderate disordered dietary rhythm group ( OR=2.63, 95%CI =2.45-2.83) and the high disordered dietary rhythm group ( OR=6.38, 95%CI = 5.93- 6.86). In addition, after stratifying by gender, dietary rhythm were positively correlated with depressive symptoms. The moderate disordered group (male: OR=2.62, 95%CI =2.37-2.89, female: OR=2.67, 95%CI =2.40-2.97) and the highly disordered group (male: OR=5.74, 95%CI =5.19-6.35, female: OR=7.11, 95%CI =6.40-7.89) were positively correlated with depressive symptoms. After stratification by physical activity levels, low, moderate and above physical activity levels among adolescents in the disordered dietary rhythm group (low physical activity: OR=2.91, 95%CI =2.58-3.29, moderate and above physical activity: OR= 2.50, 95%CI =2.28-2.74), high disordered group (low physical activity: OR=6.51, 95%CI =5.94- 7.13 , moderate and higher physical activity: OR=6.18, 95%CI =5.47-6.97) were positively associated with depressive symptoms ( P <0.01). There was an interaction between dietary rhythm and physical activity levels in regard to the development of depressive symptoms in adolescents, taking the group with moderate and above physical activity levels and low disordered dietary rhythm as the reference,the detection rate of which was higher in adolescents with low levels of physical activity and those in the moderate or high disordered dietary rhythm group ( OR=1.50, 3.90, 95%CI=1.39-1.61, 3.63-4.19, P <0.01). Conclusions Dietary rhythm disorders were found to be positively associated with depressive symptoms in adolescents. Regular dietary behaviors and increased physical activity play an important positive role in promoting adolescent mental health.

Objective: To analyze the effects of outdoor activities, sedentary behaviors and sleep duration on the risk of poor vision among primary and secondary school students after replacing them with each other, so as to provide a reference for precise intervention in the prevention and control of myopia among children and adolescents. Methods: From March to May 2023, a stratified cluster random sampling method was used to select 6 132 students in grades 4 to 12 in Hefei, Wuhu, Suzhou and Chizhou cities in Anhui Province. A questionnaire survey was conducted to collect the basic information, outdoor activities, sedentary behavior, and sleep duration, and a visual inspection was carried out by 5 m standard logarithmic visual acuity chart. The single activity model, segmentation model and isotemporal substitution model were used to analyze the relationship between outdoor activities, sedentary behaviors, sleep, and poor vision, and stratified analysis was performed by gender. Results: The detection rate of poor vision among the 6 132 primary and secondary school students was 76.9%, and the detection rate of poor vision was higher for girls ( 81.1 %) than for boys (72.6%), and the difference was statistically significant ( χ 2=61.37, P <0.01). The results of the single activity model and segmentation model showed that outdoor activity and sleep duration were correlated with a reduced risk of poor vision in primary and secondary school students ( OR =0.87, 0.88; 0.88, 0.91), while sedentary behavior was correlated with an increased risk of poor vision ( OR =1.05, 1.03) ( P <0.05). The results of the isotemporal substitution model showed that replacing the same amount of sedentary behavior with 1 h/d of outdoor activity was associated with 15% reduction in the risk of poor vision ( OR = 0.85), and replacing the same amount of sedentary behavior with 1 h/d of sleep was associated with a 12% reduction in the risk of poor vision ( OR =0.88) ( P <0.05). The results of the isotemporal substitution model stratified by gender showed that replacing the same amount of sedentary behavior with 1 h/d of outdoor activity and 1 h/d of sleep were associated with 22% and 8% reduction in the risk of poor vision in male students ( OR =0.78, 0.92), and replacing the same amount of sedentary behavior with 1 h/d of sleep was associated with 18% reduction in the risk of poor vision in female students ( OR =0.82) ( P <0.05). Conclusion Replacing sedentary behavior with 1 h/d of outdoor activity for boys and 1 h/d of sleep for girls and boys could reduce the risk of poor vision.