Leisure-time sedentary behaviors are differentially associated with all-cause dementia regardless of engagement in physical activity.

Sedentary behavior (SB) is associated with cardiometabolic disease and mortality, but its association with dementia is currently unclear. This study investigates whether SB is associated with incident dementia regardless of engagement in physical activity (PA). A total of 146,651 participants from the UK Biobank who were 60 years or older and did not have a diagnosis of dementia (mean [SD] age: 64.59 [2.84] years) were included. Self-reported leisure-time SBs were divided into two domains: time spent watching television (TV) or time spent using a computer. A total of 3,507 individuals were diagnosed with all-cause dementia over a mean follow-up of 11.87 (±1.17) years. In models adjusted for a wide range of covariates, including time spent in PA, time spent watching TV was associated with increased risk of incident dementia (HR [95% CI] = 1.24 [1.15 to 1.32]) and time spent using a computer was associated with decreased risk of incident dementia (HR [95% CI] = 0.85 [0.81 to 0.90]). In joint associations with PA, TV time and computer time remained significantly associated with dementia risk at all PA levels. Reducing time spent in cognitively passive SB (i.e., TV time) and increasing time spent in cognitively active SB (i.e., computer time) may be effective behavioral modification targets for reducing risk of dementia regardless of engagement in PA.

The impact of using digitally-mediated social stories on the perceived competence and attitudes of parents and practitioners supporting children with autism.

A Social Story (SS) is a highly acceptable and widely used intervention by the autism community. Yet, inconsistent implementation of the intervention is reported to be one of the causes of variability in terms of outcome research, particularly in a naturalistic context. This study aimed to (1) investigate whether digitally-mediated social stories (SSs) can improve competence in developing and delivering a SS and thus contribute towards improved implementation, and (2) investigate the impact of the digitally-mediated SS on attitudes towards the SS intervention. Ninety-three participants took an initial pre-engagement survey. Forty-eight of these participants also complete a post-engagement survey. A pre-post design was utilised with the participants who completed both surveys. These 48 participants were invited to develop a digitally-mediated SS with the aim of exploring how digitally-mediated SSs impacted perceived competence and attitudes. Post-engagement data was collected two weeks after the pre-engagement data. Outcomes of this study indicate that both perceived competence and attitudes improved after engaging with digitally-mediated SSs. It is concluded that digitally-mediated SS not only impacted the integrity of how the intervention was delivered but also the beliefs in the participants' capabilities to develop and deliver a SS. Digitally-mediated SS, thus, has the potential to effectively support development and delivery whilst also addressing challenges related to intervention implementation in a naturalistic context.

Reading digital- versus print-easy texts: a study with university students who prefer digital sources

The transition from on-paper to on-screen reading seems to make it necessary to raise some considerations, as a greater attentional efort has been claimed for print texts than digital ones. Not surprisingly, most university students prefer this digital medium. This research aims to examine reading times by contextualizing this phenomenon into two processes: namely, word recognition and reading comprehension task on paper and on screen. Thus, two diferent tasks­counterbalanced into digital and print mediums­were carried out per each participant with a preference for a digital medium: a reading comprehension task (RCT) and a lexical decision task (LDT) after reading a specifc story. Participants were slower reading print texts and no statistically signifcant diferences were found in RCT accuracy. This result suggests that the task required more cognitive resources under the print medium for those with a worse comprehension performance in reading, and a more conservative pattern in digital RCT for those with a better performance.

International trade and finance exploration using network model of computer trade platform.

International trade becomes increasingly frequent with the deepening of economic globalization. In order to ensure the stable and rapid development of international trade and finance, it is particularly crucial to predict the sales trend of foreign trade goods in advance through the network model of computer trade platform. To optimize the accuracy of sales forecasts for foreign trade goods, under the background of "Internet plus foreign trade", the controllable relevance big data mining of foreign trade goods sales, personalized prediction mechanism, intelligent prediction algorithm, improved distributed quantitative and centralized qualitative calculation are taken as the premise to design dynamic prediction model on export sales based on controllable relevance big data of cross border e-commerce (DPMES). Moreover, after the related experiments and comparative discussions, the forecast error ratios from the first quarter to the fourth quarter are 2.3%, 2.1%, 2.4% and 2.4% respectively, which are also within the acceptable range. The experimental results show that the design combines the advantages of openness and extensibility of Internet plus with dynamic prediction of big data, and achieves the wisdom, quantitative and qualitative prediction of the volume of goods sold under the background of "Internet plus foreign trade", which is controlled by the relevant data of foreign trade. The overall performance of this design is stronger than the previous models, has better dynamic evolution and high practical significance, and is of great significance in the development of international trade and finance.

Patterns and Predictors of Television Viewing and Computer Use Among Women Living in Socioeconomically Disadvantaged Neighborhoods: A Prospective Cohort Study.

BACKGROUND: Socioeconomically disadvantaged women are at an increased risk of sedentary behaviors including television (TV) viewing and computer use, so identifying determinants of these behaviors is important. METHODS: Women (n = 4349) self-reported weekly TV and computer time (in minutes per week), sociodemographic, and health data at 3 time points (2007-2013). Mixed-effect negative binomial regression was used to determine the baseline determinants of TV viewing and computer use over time, adjusting for confounders. RESULTS: Over 5 years, median TV viewing decreased while median computer time increased. Cross-sectionally TV viewing was highest among participants classified as obese, with poorer health, current smokers, with lower education, not working, with no income, without partners and with no children and computer time was greater among younger women, living in urban areas, working full time, with higher education, without partners and with no children. Average computer time per year increased among those not working (7%), with lower education (5%), and with children (5%) but decreased among those with higher education (1%). However, no factors were associated with a change in TV viewing over time. CONCLUSION: Among socioeconomically disadvantaged women, interventions aimed at preventing increases in computer time should consider women with lower education, not working, and with children in their design.

COVID-19 Home Quarantine Accelerated the Progression of Myopia in Children Aged 7 to 12 Years in China.

Purpose: To investigate the effect of home quarantine during the COVID-19 pandemic on myopia progression in children and its associated factors. Methods: Myopic children aged 7 to 12 years with regular follow-up visits every half a year from April 2019 to May 2020 were included. Cycloplegic refraction was measured at baseline and at two follow-up visits. The first follow-up visit (visit 1) was conducted before the COVID-19 home quarantine, whereas the second (visit 2) was four months after the home quarantine. Myopia progression at visits 1 and 2 were compared. Factors associated with changes in myopia progression were tested with a multiple regression analysis. Results: In total, 201 myopic children were enrolled. There was a significantly greater change in spherical equivalent at visit 2 (-0.98 ± 0.52 D) than at visit 1 (-0.39 ± 0.58 D; P < 0.001). Students were reported to have spent more time on digital devices for online learning (P < 0.001) and less time on outdoor activities (P < 0.001) at visit 2 than at visit 1. Children using television and projectors had significantly less myopic shift than those using tablets and mobile phones (P < 0.001). More time spent on digital screens (ß = 0.211, P < 0.001), but not less time on outdoor activities (ß = -0.106, P = 0.110), was associated with greater myopia progression at visit 2. Conclusions: Changes in behavior and myopic progression were found during the COVID-19 home quarantine. Myopic progression was associated with digital screen use for online learning, but not time spent on outdoor activities. The projector and television could be better choices for online learning.

Effects of the excessive use of electronic screens on vision and emotional state / Efeitos do uso excessivo de telas eletrônicas na visão e no estado emocional

ABSTRACT Objective To investigate relations between electronic screen use and eye health in a representative sample of the Brazilian population. Methods Data were collected online and analyzed at a private Brazilian hospital (Provisão Hospital, Maringá, Brazil). Male and female individuals aged 12 to 35 years participated in the study. A population-based cross-sectional survey based on a questionnaire developed using the Google Forms interface was carried out. The questionnaire was answered anonymously in order to ensure the confidentiality of data and the privacy of participants. Data were collected between October 13, 2020, and January 30, 2021. Results A total of 200 questionnaires were completed. Most responders were young people aged 18 to 27 years. Daily electronic device use time reported by responders ranged from more than 5 hours (150; 75.5%) to 3 to 5 hours/day (28; 14%) or 2 to 3 hours/day (16; 8%). Only a small proportion of responders (2.5%) used these devices less than 1 hour per day. Most participants had myopia (164; 84%) and/or astigmatism (151; 75.5%), whereas keratoconus was less prevalent (34; 17%). However, 92 participants were unable to say whether they had these diseases or not. Most participants reported eye symptoms after screen use (red eyes, fatigue, dry and gritty eyes and blurred vision). Mental issues such as smartphone dependence and difficulties to communicate while using electronic devices were also addressed. Most responders reported dependence and communication problems. Conclusions Most young people in this sample had sings of eye disease, including keratoconus. Smartphone dependence and addition was also observed. Findings presented may inform future studies and help health authorities to properly guide public health strategies aimed at eye disease prevention.

RESUMO Objetivo Investigar o uso de telas na saúde ocular em uma amostra populacional brasileira. Métodos Os dados foram adquiridos on-line, e as análises foram realizadas em uma clínica privada na Região Sul do Brasil. Os participantes foram indivíduos de 12 a 35 anos, de ambos os sexos. Foi realizada pesquisa transversal de base populacional por meio de questionário elaborado na plataforma Google Forms. O questionário foi respondido de forma anônima, mantendo o sigilo dos dados coletados e a privacidade dos participantes. A coleta de dados teve início em 13 de outubro de 2020 e término em 30 de janeiro de 2021. Resultados Foram respondidos 200 questionários. A maioria foi de jovens entre 18 e 27 anos. O tempo de uso de dispositivos eletrônicos durante o dia foi de mais de 5 horas para 150 (75,5%) entrevistados, 28 (14%) gastavam de 3 a 5 horas por dia, 16 (8%) de 2 a 3 horas por dia e uma pequena parte dos entrevistados (2,5%) usava menos de 1 hora por dia. A maioria dos participantes tinha miopia (164; 84%) e/ou astigmatismo (151; 75,5%). Ceratocone foi menos prevalente (34; 17%), entretanto 92 pessoas não sabiam a resposta. A maioria dos participantes teve problemas nos olhos após o uso da tela, como olhos vermelhos, cansados e secos, além de visão turva. Questões mentais, como dependência de smartphones e dificuldade de comunicação durante o uso do dispositivo, também foram abordadas. A maioria dos entrevistados demonstrou dependência e problemas de comunicação. Conclusões A maior parte dos jovens apresentou quadro de doenças oculares, incluindo ceratocone. Dependência e adição de smartphone também foram observados. Esses resultados apoiam a identificação de fatores associados à patologia ocular, servindo de base para estudos futuros, e podem auxiliar às autoridades de saúde no direcionamento adequado das atividades de prevenção e controle em saúde pública.

Are the problem spaces of economic actors increasingly virtual? What geo-located web activity might tell us about economic dynamism.

The principal questions this research will address are: 1) whether a higher propensity to visit websites of interest to actual or nascent entrepreneurs is associated with higher rates of new firms births in an area; 2) whether a higher propensity to visit websites of interest to those working on design problems is associated with the quality of business in terms of orientations toward design or innovation; and 3) whether a higher propensity to visit websites of interest to those pursuing arts as an avocation is associated with an increased ability to find nonobvious solutions that might be manifest in business quality. The unique data that allow examining these questions were compiled from billions of web hits by geo-located devices. These data are combined with both detailed establishment level data with reliable information on the innovation and design orientation of firms, and a longitudinal census of all establishments with a formal credit relationship in the U.S. The findings confirm that businesses located in areas with a high propensity to visit design and arts avocation websites are more likely to pursue more far ranging innovation and are more likely to integrate design into their innovation processes. Firm birth rates are higher in areas with a high propensity to visit websites of interest to entrepreneurs, and the existence of high growth firms is strongly associated with demonstrated interest in design and arts avocation websites. The possible uses of these nontraditional measures as indicators of economic dynamism are discussed.

Intergenerational Effects on the Impacts of Technology Use in Later Life: Insights from an International, Multi-Site Study.

As the use of technology becomes further integrated into the daily lives of all persons, including older adults, it is important to investigate how the perceptions and use of technology intersect with intergenerational relationships. Based on the international multi-centered study Technology In Later Life (TILL), this paper emphasizes the perceptions of older adults and the interconnection between technology and intergenerational relationships are integral to social connectedness with others. Participants from rural and urban sites in Canada and the UK (n = 37) completed an online survey and attended a focus group. Descriptive and thematic analyses suggest that older adults are not technologically adverse and leverage intergenerational relationships with family and friends to adjust to new technologies and to remain connected to adult children and grandchildren, especially when there is high geographic separation between them. Participants referenced younger family members as having introduced them to, and having taught them how to use, technologies such as digital devices, computers, and social networking sites. The intergenerational support in the adoption of new technologies has important implications for helping older persons to remain independent and to age in place, in both age-friendly cities and in rural communities. The findings contribute to the growing literature in the fields of gerontology and gerontechnology on intergenerational influences and the impacts of technology use in later life and suggest the flexibility and willingness of older persons to adopt to new technologies as well as the value of intergenerational relationships for overcoming barriers to technology adoption.

Screen time and sleep disorder in preschool children: identifying the safe threshold in a digital world.

OBJECTIVES: Sleep disorder is a common problem in children that can jeopardize their health and well-being. With the popularity of electronic devices such as portable tablets and smartphones in the 21st century, children are spending much more time on screen, but the impact of such change on children's sleep disorder has been less investigated so far. This study aims to examine the dose-response association between time spent on different electronic devices and children's sleep disorder. STUDY DESIGN: The design of this study is a cross-sectional study. METHODS: We randomly selected 2278 children aged 3-6 years from 15 kindergartens in Tongling, China. The potentially non-linear association between screen-viewing time (i.e. television [TV], computer, iPad, Phone) and the risk of sleep disorder was examined using a logistic generalized additive model. RESULTS: We observed a J-shaped association between TV viewing time and the risk of sleep disorder, with a threshold of 1 h/day. For each 1 h/day increment in TV viewing time over the threshold, the risk of sleep disorder increased by 12.35% (95% confidence interval: 1.87-23.92%). This association seemed to be greater for girls than boys and for TV viewing at weekend than on weekdays, but the difference was not statistically significant (P-value>0.05). We did not find adequate evidence of an adverse effect of more time spent on computer, iPad and Phone. CONCLUSIONS: This study suggests a positive but non-linear relationship between time spent on watching TV and sleep disorder in Chinese preschool children. Setting the TV viewing time limit less than 1 h/day may help reduce the risk of developing sleep disorder. Further investigation is also needed to examine and compare the effects of heavy use of other electronic devices on sleep disorder.

Clusters of non-dietary obesogenic behaviors among adolescents in Brazil: a latent profile analysis.

OBJECTIVES: To identify patterns of non-dietary obesogenic behaviors, and social and environmental factors associated with overweight and obesity (OWOB). METHODS: A representative sample (n = 5520) of high school students (55.4% girls, 16.3 ± 1.0 years) from Pernambuco State, Brazil. Latent profile analyses were performed using self-reported daily sleep duration, television use, computer use, videogame use, seated time during the week and weekend days, physical activity, and active commuting to school during the week. Social and environmental factors and body mass index were included to identify classes. Multinomial analysis explored differences in social, environmental factors, and BMI by classes. RESULTS: Five patterns were identified [Computer users (C1), Short sleepers (C2), Typical behaviors (C3), Techno-active-gamers (C4), and Lower screen engagement (C5)]. Three groups (C1, C3 and C4) included students from better social conditions and a more urbanized environments. The prevalence of OWOB was higher in C1 (34.5%; 95% CI 31.1-38.0) and in C2 (29.7%; 95% CI 26.1-33.5) compared to C5 (23.3% 95% CI 21.3-25.3). CONCLUSIONS: In one of the poorest regions of Brazil, different groups of social/environmental factors and behavior patterns emerged associated with OWOB.

Measuring the Functional Abilities of Children Aged 3-6 Years Old with Observational Methods and Computer Tools.

The analysis of functional abilities and their development in early childhood (0-6 years old) are fundamental aspects among young children with certain types of developmental difficulties that can facilitate prevention, through programmed interventions adapted to the needs of each user (student or patient). There are, however, few investigations to date, that have analyzed the use of automated tools for recording and interpreting the results of the initial assessment. Here, a protocol is presented to examine the functional abilities in early childhood in young children, aged between 3-6 years old, with intellectual disabilities, but the protocol can also be used for ages 0 to 6 years. The protocol makes use of a computer application, eEarlyCare, that facilitates the interpretation of the results of systematic observations, which are recorded in natural environments by professionals trained in early intervention. The software can be used to analyze 11 functional areas (Food Autonomy, Personal Care and Hygiene, Dressing and Undressing Independently, Sphincter Control, Functional Mobility, Communication and Language, Daily Life Routines, Adaptive Behavior and Attention) and a total of 114 different behaviors. Its use facilitates the analysis of the observed abilities and greatly assists early intervention. Compared to other observational methods, it allows a more efficient use of personal and material resources. The use of the computer application facilitates the recording of the observation results, which helps with organization and reflection on the observations. The software displays the observation results on-screen compared to normal developmental parameters. This information can be referred to for decision-making about the most suitable intervention program for each user (student or patient). Likewise, clustering techniques are applied to analyze the relation between the type of intellectual disabilities and functional development identified with the software, a relation that is intended to serve as a guide for early-care professional intervention.

Social inequalities in traditional and emerging screen devices among Portuguese children: a cross-sectional study.

BACKGROUND: Children are often exposed to too much screen time but few studies have explored the use of old and new digital media among young children. This study assesses screen time, including traditional and mobile devices, in pre-school and elementary school-aged children, according to their gender, age, and socioeconomic position (SEP). METHODS: A total of 8430 children (3 to 10 years; 50.8% boys) from the north, center and south-central Portugal were included in the present study. Data was collected by a parental questionnaire during 2016/2017. Children's screen time (by media device, weekdays and at the weekend; calculated by mean minutes per day) were reported by parents. Analysis were carried to compare screen time by children's age, gender and family SEP (classified using father's educational degree). RESULTS: Daily screen time was high both in children aged 3 to 5 and 6 to 10 years - 154 min/day (95% CI: 149.51-158.91) and 200.79 min/day (95% CI: 197.08-204.50), respectively - and the majority of children, independently of their gender, exceed the recommended 2 h/day of screen viewing. Children are still primarily engaging in screen time through television but the use of mobile devices, particularly tablets, were already high among 3 year-old children and increased with age. SEP was a negative predictor of screen time in the linear regression analysis, including after adjustment. CONCLUSIONS: Considering the negative health impacts of excessive screen time, recognizing subgroups at risk of excessive screen time and identifying how each device is used according to age is fundamental to enable appropriate future interventions. The screen time in children aged 3-10 years is longer than the recommended, particularly among boys and in those children from lower SEP. Parents and policymakers should have in mind that children spend most of their screen time watching television but mobile devices are becoming extremely popular starting at a young age.

Nonrelocatable Occupations at Increased Risk During Pandemics: United States, 2018.

Objectives. To characterize which occupations in the United States could likely work from home during a pandemic such as COVID-19.Methods. I merged 2018 US Bureau of Labor Statistics (BLS) national employment and wage data with measures ranking the importance of computer use at work and the importance of working with or performing for the public from the BLS O*NET survey.Results. Approximately 25% (35.6 million) of US workers are employed in occupations (such as technology, administrative, financial, and engineering) that could be done from home; the remaining 75% work in occupations (including health care, manufacturing, retail, and food services) that are challenging to do from home.Conclusions. Most US workers are employed in occupations that cannot be done at home, putting 108.4 million workers at increased risk for adverse health outcomes related to working during a pandemic. These workers tend to be lower paid. The stress experienced by lower-income groups, coupled with job insecurity, could result in a large burden of mental health disorders in the United States in addition to increased cases of COVID-19 from workplace transmission.

Prevalence of primary headache disorders among information technology staff in China: the negative effects of computer use and other correlative factors.

BACKGROUND: To date, there have been very few studies that have explored the relationship between headaches and computer use. The chief aim of this study is to investigate the prevalence of primary headache disorders among informational technology staff and identify the potential factors contributing to it. METHODS: This is a cross-sectional study based on annual health checks of employees from the information technology industry. We identified 2216 information technology staff members from Beijing by stratified random sampling who met the inclusion criteria. All participants were initially required to have a physical examination, after which they complete a general situation questionnaire that included a headache screening question. Those who had suffered from headache within the previous year also completed the questionnaire developed by Lifting the Burden. The International Classification of Headache Disorders 3(ICHD-3) criteria was used for the diagnosis of headache. RESULTS: A total of 2012 valid questionnaires (males, 1544 [76.7%]; females, 468 [23.3%]) were obtained from 2216 participants for a response rate of 90.8%. A total of 619 participants were diagnosed with primary headache, the one-year prevalence of which was 30.8%. Regarding the classification of the primary headache, 152 participants suffered from migraine, with a one-year prevalence of 7.6%; 440 and 27 suffered from tension-type headache and unclassified headaches, with one-year prevalences of 21.9 and 1.3%, respectively. Multivariate regression analysis showed that female gender was a risk factor for migraine and tension-type headache (OR 3.21[95% CI 2.28-4.53] and 1.88[95% CI 1.47-2.40], respectively). Age was also related to migraine and tension-type headache. The 41-50 age group had 2.02 times the probability of migraine, and the 31-40 age group had 1.89 times the probability of tension-type headaches compared to the 18-30 age group. Obesity and excessive computer use (more than 12 h per day) were also factors contributing to tension-type headache (OR: 2.61[95% CI 1.91-3.56] and 1.63[95% CI 1.18-2.25], respectively). CONCLUSIONS: The one-year prevalence of primary headache in this population was 30.8%. The prevalence of tension-type headache in this population was higher than that in the general Chinese population. The occurrence of primary headache is correlated with many factors, among which excessive computer use significantly contributed to the risk of tension-type headache.

Exposure to electronic devices and sleep quality in adolescents: a matter of type, duration, and timing.

OBJECTIVES: The objective was to describe (1) the type, (2) the amount of use, and (3) the time of usage of electronic devices, for school days and weekends, as well as its impact on adolescents' sleep quality. DESIGN: A cross-sectional study using hierarchical regressions accounting for confounding sleep-related variables was used. SETTING: The participants were from six public schools in Porto Alegre, Brazil. PARTICIPANTS: The participants included 177 students of both sexes aged between 11 and 18 years. MEASUREMENTS: An electronic usage diary assessed the span of time during which the electronic device was used (separated by "TV and computer monitors", "tablets, e-readers and portable video games," and "cell phones") for school days and weekends. The Munich Chronotype Questionnaire was used to assess sleep duration, midpoint of sleep, and social jetlag. Sleep quality was assessed using the Pittsburgh Sleep Quality Index. RESULTS: Greater nighttime use and last time of use of cell phones at night are associated with worse sleep quality in univariate analyses. A hierarchical regression model shows that poor sleep quality associates with shorter sleep duration on school days and with a delayed midpoint of sleep on weekends. Electronic device use did not reach statistical significance in the regression model with confounding factors. CONCLUSIONS: Adequate sleep duration is imperative to maintain a good sleep quality on school days, independently of the use of cell phones. It is important to underpin the need for evaluation of sleep phase and chronotype in future research on the topic aiming to elucidate its relationship with electronic use on school-free days.

Generation of simple polygons from ordered points using an iterative insertion algorithm.

To construct a simple polygon from a set of plane points, we propose an iterative inserting ordered points (IIOP) algorithm. Using a given a set of ordered non-collinear points, a simple polygon can be formed and its shape is dependent on the sorting method used. To form such simple polygons with a given set of plane points, the points must first be ordered in one direction (typically, the x-axis is used). The first three points in the set are used to form an initial polygon. Based on the formed polygon, new polygons can be iteratively formed by inserting the first point of from among the remaining set of points, depending on line visibility from that point. This process is carried out until all the points are inserted into the polygon. In this study, we generated 20, 50, and 80 plane points and used the proposed method to construct polygons. Experimental results show that these three polygons are all simple polygons. Through theoretical and experimental verification, we can concluded that when given a set of non-collinear points, a simple polygon can be formed.

Cohort effects associated with reduced sleep duration in adolescents.

OBJECTIVE: The purpose of this study is to examine how the sleep duration changes during adolescence across the seventh, eighth, ninth, and 10th grade periods, and to determine whether there is a difference between the cohorts. METHOD: For these purposes, we used the latent growth curve modeling and the multi-group analysis involving 2081 students (2000-birth cohort data) and 2254 students (1997-birth cohort data) who participated in the Korean Children and Youth Panel Survey. The data were collected using a stratified multistage cluster sampling method. RESULTS: Sleep duration became shorter as age increased. Furthermore, the sleep duration of the 2000-birth cohort became shorter than the sleep duration of the 1997-birth cohort. Specifically, the mean value of the initial sleep duration of the 2000-birth cohort was 8.09 h, which was significantly shorter than the initial value 8.36 h of the sleep duration of the 1997-birth cohort. In addition, multi-group analysis revealed that the trajectories of sleep duration and its predictors were varied by cohort. Specifically, parent supervision, peer relationship, and electronic media factors (smartphone overuse, time spent on using computer and playing games) explained the cohort effect. CONCLUSION: These findings suggest that environmental factors such as increasing use of electronic media or pressure regarding higher education to adolescents could be associated with reduced sleep duration.