The influence of leisure screen time on sleep patterns and feeding behaviors in primary school children

This study aimed to determine whether adolescents’ leisure screen time differed during the coronavirus disease 2019 (COVID-19) pandemic compared to before the pandemic, and to identify factors that affect leisure screen time among Japanese high school students. The Health Behavior in School Children questionnaire was used to investigate differences in eating habits and physical and mental health. The results showed that the leisure screen time of Japanese high school students was 2.6 h (SD = 1.4) before the pandemic, and 3.2 h (SD = 1.5) during the pandemic. The factors that increased leisure screen time were found to differ between boys and girls. No significant deterioration in physical and mental health was observed. The impact of the pandemic on eating habits differed in boys and girls. Boys reported “not feeling great about life” as a factor that increased leisure screen time during the pandemic, suggesting that negative emotions influenced the increase in leisure screen time. The pandemic had a significant impact on girls’ leisure screen time. Longer screen time should be carefully monitored because it can lead to sleep disturbances, worsening of mental health, and obesity. Compared with before the pandemic, the health status of boys and girls changed little. Eating habits tended to improve for both boys and girls.

Adolescence is a critical period for mental health vulnerability alongside rising digital media exposure. Current evidence often fails to distinguish the distinct roles of leisure screen time (LST) quantity and addictive patterns like internet gaming disorder (IGD) on a comprehensive range of mental health outcomes. This study aimed to investigate the independent and joint associations of LST and IGD with multiple mental health conditions among Chinese adolescents. We conducted a school-based, cross-sectional survey in Sichuan Province, China. Participants were recruited by random cluster sampling from 20 public schools. The sample comprised 13,240 adolescents (6659/13,240, 50.3% girls) with a mean age of 15.4 (SD 1.6) years. LST was self-reported, and IGD was evaluated using the Internet Gaming Disorder Scale-9 Item Short Form (IGDS9-SF). Mental health outcomes included overall mental health status and 5 specific diseases: psychological distress, depression, paranoia, insomnia, and suicidal ideation, all assessed using validated scales. The prevalence of excessive LST, IGD, and any mental health disorder was 48.2% (6378/13,240; 95% CI 47.3%-49.0%), 1.4% (188/13,240; 95% CI 1.2%-1.6%), and 55.8% (7387/13,240; 95% CI 54.9%-56.7%), respectively. After adjustment, excessive LST (odds ratio [OR] 1.18, 95% CI 1.09-1.27) and IGD (OR 6.58, 95% CI 5.02-8.62) were independently associated with poor mental health. A dose-response relationship existed for LST quartiles (Q2: OR 1.15, 95% CI 1.04-1.26; Q3: OR 1.24, 95% CI 1.12-1.37; Q4: OR 1.31, 95% CI 1.18-1.46; Ptrend<.001). Excessive LST was associated with depression (OR 1.16, 95% CIs 1.05-1.29), paranoia (OR 1.22, 95% CI 1.11-1.34), and suicidal ideation (OR 1.15, 95% CI 1.04-1.28), while IGD was associated with all 5 disorders, most notably depression (OR 6.43, 95% CI 4.56-9.06) and paranoia (OR 5.77, 95% CI 4.05-8.21). IGD consistently demonstrated stronger associations than LST: psychological distress (OR 4.40, 95% CI 3.12-6.19 vs OR 1.14, 95% CI 0.98-1.33), depression (OR 6.43, 95% CI 4.56-9.06 vs OR 1.16, 95% CI 1.05-1.29), paranoia (OR 5.77, 95% CI 4.05-8.21 vs OR 1.22, 95% CI 1.11-1.34), insomnia (OR 2.90, 95% CI 2.09-4.05 vs OR 1.12, 95% CI 102-1.22), and suicidal ideation (OR 3.85, 95% CI 2.76-5.37 vs OR 1.15, 95% CI 1.04-1.28). Adolescents with both excessive LST and IGD demonstrated the highest odds of mental health disorders (OR 7.35, 95% CI 5.29-10.22). No significant interaction was found on additive or multiplicative scales. Both excessive LST and IGD are independently associated with mental health disorders in adolescents, with IGD showing a substantially stronger association. This study is distinct from prior research by simultaneously investigating both screen time quantity and addictive usage patterns, and by comprehensively assessing 5 distinct mental health outcomes. Longitudinal studies are needed to better understand the long-term effects.

We examined the association between changes in physical activity and leisure screen time and mental health outcomes during the early stages of the recommended COVID-19 stay-at-home period in a national sample of Mexican adults aged 18 years or older. A cross-sectional online survey conducted from May 29 through July 31, 2020, among 1,148 participants, reported time spent in physical activity and leisure screen time during a typical week before (retrospectively) and a week during the COVID-19 stay-at-home period. Mental health outcomes during this period were measured with the Depression, Anxiety and Stress Scale (DASS-21). Linear regression models were used to estimate the associations between changes in physical activity and leisure screen time and mental health outcomes by socioeconomic status (SES), adjusting for potential confounders. Compared with maintaining high levels of physical activity or increasing them, decreasing physical activity was associated with higher stress scores overall, and among people of high SES, with higher scores for DASS-21, depression, and anxiety. Among participants of low and medium SES only, increasing screen time was associated with higher DASS-21, depression, anxiety, and stress scores compared with maintaining low or decreasing leisure screen time. Results highlight the potential protective effect of physical activity and limited leisure screen time on mental health in the context of COVID-19 stay-at-home restrictions.

This study aimed to understand differences in leisure, educational/work and social screen time behaviours experienced by parents and children due to COVID-19 lockdown restrictions, which may inform behaviour change strategies and policy in the transition to a COVID-normal life. Participants in the “Our Life at Home” study (n = 218 parents from Australia, 43.4 ± 6.8 years, 88% female) completed a cross-sectional online survey in April/May 2020. Parents recalled their own and their child (8.7 ± 2.0 years, 42% female) or adolescents (15.0 ± 1.5 years, 50% female) participation in nine screen time behaviours in the past month (during lockdown) and retrospectively for February 2020 (pre-lockdown), providing data on 436 individuals. Screen time behaviours included leisure (computer/laptop and tablet/smartphone for leisure, TV/videos/DVDs and game consoles); education/work (computer/laptop and tablet/smartphone for work/education); and social screen time (computer/tablet/smartphone for social communication with friends, family and work (parents only)). Wilcoxon signed-rank tests and effect sizes (r) compared the time spent in each behaviour pre-lockdown and during lockdown. Large differences were observed in social (parents: r = 0.41–0.57; children: r = 0.55–0.65; adolescents: r = 0.28–0.43) and education (children: r = 0.50–0.65 and adolescents: r = 0.25–0.37) behaviours. There were small or no differences in leisure time screen use. COVID-19 lockdown restrictions have impacted parent’s and children’s screen time, and future research and policy should consider strategies to support families to manage screen time.

Leisure screen time predicts free sugar consumption in children

BackgroundLimited evidence exists on how sedentary behaviour changes across occupational classes. We examined the changes of between occupational class and changes in sedentary time over a 5-year follow-up among young and early midlife employees.MethodsWe used data from the Helsinki Health Study follow-up survey among employees of City of Helsinki, Finland, in 2017 (aged 19-39 years) and 2022 (n = 2,762; 81% women). Sedentary time (minutes/day) was assessed across total sitting time and its five subdomains (work, leisure screen time, reading, transport, other). Occupational class was categorized into manual and routine non-manual, semi-professional, and professional. Linear mixed models with fixed effects estimated β-coefficients and 95% confidence intervals (CIs), adjusting for sociodemographic and health-related factors.ResultsDuring the 5-year follow-up, daily total sedentary time increased (β = 46 min [95% CI 37.6-54.4]), as did sedentary time during work (β = 24 min [95% CI 18.1-29.7]), leisure screen time (β = 21 min [95% CI 16.2-24.8]), and leisure reading (β = 3 min [95% CI: 0.5-5.5]), whereas sedentary time in transportation decreased (β=-5 min [95% CI -8.5- -1.5]). Women in the lowest occupational class increased total sedentary time (β = 25 min [95% CI 0.1-50.3]) and leisure screen time (β = 14 min [95% CI 0.8-26.6]) compared to those with the highest occupational group, narrowing occupational class differences in total sedentary time and increasing the difference in screen time. Women with the middle occupational group increased their work-related sedentary time (β = 21 min [95% CI 4.4-36.6]), narrowing occupational class differences to the highest occupational class group.ConclusionsSedentary time increased among all participants, with the greatest increases observed in women of the lowest occupational class, particularly in leisure screen time. Our findings raise public health concerns about the growing sedentary behaviours among young and early midlife employees.Key messages• Weekly sedentary time increased by 4 hours over the 5-year follow-up among all employees, with the largest increase among women in lowest occupational class, particularly in leisure screen time.• Reducing sedentary behaviour at work and during leisure is essential to address occupational class-related health disparities.

&lt;p dir="ltr"&gt;&lt;b&gt;Introduction&lt;/b&gt;: Depression and anxiety are the most common causes of illness in Europe, especially among young people, and suicide is the leading cause of death among adolescents in Sweden. The use of digital media is often discussed in relation to mental health. Time recommendations, bans, legislation, and media use guidelines are frequently published-often without clear evidence of their effects or mechanisms of action. This thesis aims to improve our understanding of this phenomenon.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Aim&lt;/b&gt;: Through three studies (I, II, III), this thesis explores the main psychological health mechanisms involved in how leisure screen time may contribute to mental health issues-or simply co-occur with them. It aims to establish a theoretically grounded, empirically supported, and scientifically replicable framework and model for understanding how screen time affects mental health.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Methods&lt;/b&gt;: Longitudinal three-wave psychometric health data were collected over six years in conjunction with two school-cluster randomized trials on psychoeducation and suicide prevention, always administered in classroom settings. Intervention effects were held constant or nullified. Three statistical analyses of screen-health associations were conducted using adolescent health data (N = 4810 from 55 Swedish schools; N = 1544 from 30 schools in seven European countries).&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Analyses&lt;/b&gt;: The primary health outcome was subclinical depression (BDI-II scores), which correlated with anxiety, and stress (DASS-42). All main statistical tests were longitudinal (3-12 months). Study I used hierarchical linear regression of change scores to examine screen activities and their consequences. Study II applied GEE gamma regression to examine moderating effects of coping styles and structural regression to assess their mediating pathways. Study III used preregistered, theory-driven multigroup structural equation modelling to analyze multiple mediation and simultaneous screen-sleep displacements.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Results&lt;/b&gt;: Screen time consistently had a negative impact on various sleep patterns and reduced cognitive coping styles. It was associated with small but adverse health outcomes for the average adolescent. Girls had twice the depression levels of boys and appeared more sensitive to screen-related sleep loss. Long screen times negatively affected Problem-Focused Engagement (PFE) coping, including cognitive restructuring, but not Socio-Emotional coping (EFE) (data collected before the COVID-19 outbreak). Notably, moodiness when screens were inaccessible-i.e., difficulty coping without screens-was the strongest predictor of depression in the first European study.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Discussion&lt;/b&gt;: The three studies showed that, regardless of gender, longer screen time was associated with sleep loss and/or reduced ability to cope with stress. Independent research confirms that sleep loss further reduces the tendency to use cognitive engagement coping. While causality could not be established, the correct temporal order was identified in the two latter studies, which replicated the initial exploratory findings. The final framework is termed the "Screen Time Displacement Theory of Mental Health" (though not so important). Sleep problems often underlie depression-especially among girls in this sample- where sleep facets (quality, duration, chronotype) mediated 38-57% of the depressive effect over 12 months. Problem-focused coping both mediated and moderated depression in both genders over 12 months (the screen-coping interaction effect equaled maximum +3.4 BDI-II points; p &lt; 0.01). Effective coping styles and consistently sufficient sleep are essential components of psychological and physiological resilience to depressive states, yet most adolescents do not meet conventional sleep or screen time recommendations. This thesis demonstrates the effects of screen time on mental health resilience in the general adolescent population (at least within Generation Z), as opposed to clinical samples. Various implications for public health are discussed.&lt;/p&gt;&lt;h3&gt;List of scientific papers&lt;/h3&gt;&lt;p dir="ltr"&gt;I. &lt;b&gt;Hökby S&lt;/b&gt;, Hadlaczky G ... Carli V. Are Mental Health Effects of Internet Use Attributable to the Web-Based Content or Perceived Consequences of Usage? A Longitudinal Study of European Adolescents? JMIR Ment Health. 2016. 13;3(3):e31. &lt;a href="https://doi.org/10.2196/mental.5925"&gt;https://doi.org/10.2196/mental.5925&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;II. &lt;b&gt;Hökby S,&lt;/b&gt; Westerlund J, Alvarsson J, Carli V, Hadlaczky G. Longitudinal Effects of Screen Time on Depressive Symptoms among Swedish Adolescents: The Moderating and Mediating Role of Coping Engagement Behavior. IJERPH. 2023;20(4):37. &lt;a href="https://doi.org/10.3390/ijerph20043771" rel="noreferrer" target="_blank"&gt;https://doi.org/10.3390/ijerph20043771&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;III. &lt;b&gt;Hökby S.&lt;/b&gt;, et al. Adolescents' screen time displaces multiple sleep pathways and elevates depressive symptoms over twelve months. PLOS Glob Public Health. 2025, 2;5(4):e0004262. &lt;a href="https://doi.org/10.1371/journal.pgph.0004262" rel="noreferrer" target="_blank"&gt;https://doi.org/10.1371/journal.pgph.0004262&lt;/a&gt;&lt;/p&gt;

&lt;p dir="ltr"&gt;&lt;b&gt;Introduction&lt;/b&gt;: Depression and anxiety are the most common causes of illness in Europe, especially among young people, and suicide is the leading cause of death among adolescents in Sweden. The use of digital media is often discussed in relation to mental health. Time recommendations, bans, legislation, and media use guidelines are frequently published-often without clear evidence of their effects or mechanisms of action. This thesis aims to improve our understanding of this phenomenon.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Aim&lt;/b&gt;: Through three studies (I, II, III), this thesis explores the main psychological health mechanisms involved in how leisure screen time may contribute to mental health issues-or simply co-occur with them. It aims to establish a theoretically grounded, empirically supported, and scientifically replicable framework and model for understanding how screen time affects mental health.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Methods&lt;/b&gt;: Longitudinal three-wave psychometric health data were collected over six years in conjunction with two school-cluster randomized trials on psychoeducation and suicide prevention, always administered in classroom settings. Intervention effects were held constant or nullified. Three statistical analyses of screen-health associations were conducted using adolescent health data (N = 4810 from 55 Swedish schools; N = 1544 from 30 schools in seven European countries).&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Analyses&lt;/b&gt;: The primary health outcome was subclinical depression (BDI-II scores), which correlated with anxiety, and stress (DASS-42). All main statistical tests were longitudinal (3-12 months). Study I used hierarchical linear regression of change scores to examine screen activities and their consequences. Study II applied GEE gamma regression to examine moderating effects of coping styles and structural regression to assess their mediating pathways. Study III used preregistered, theory-driven multigroup structural equation modelling to analyze multiple mediation and simultaneous screen-sleep displacements.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Results&lt;/b&gt;: Screen time consistently had a negative impact on various sleep patterns and reduced cognitive coping styles. It was associated with small but adverse health outcomes for the average adolescent. Girls had twice the depression levels of boys and appeared more sensitive to screen-related sleep loss. Long screen times negatively affected Problem-Focused Engagement (PFE) coping, including cognitive restructuring, but not Socio-Emotional coping (EFE) (data collected before the COVID-19 outbreak). Notably, moodiness when screens were inaccessible-i.e., difficulty coping without screens-was the strongest predictor of depression in the first European study.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Discussion&lt;/b&gt;: The three studies showed that, regardless of gender, longer screen time was associated with sleep loss and/or reduced ability to cope with stress. Independent research confirms that sleep loss further reduces the tendency to use cognitive engagement coping. While causality could not be established, the correct temporal order was identified in the two latter studies, which replicated the initial exploratory findings. The final framework is termed the "Screen Time Displacement Theory of Mental Health" (though not so important). Sleep problems often underlie depression-especially among girls in this sample- where sleep facets (quality, duration, chronotype) mediated 38-57% of the depressive effect over 12 months. Problem-focused coping both mediated and moderated depression in both genders over 12 months (the screen-coping interaction effect equaled maximum +3.4 BDI-II points; p &lt; 0.01). Effective coping styles and consistently sufficient sleep are essential components of psychological and physiological resilience to depressive states, yet most adolescents do not meet conventional sleep or screen time recommendations. This thesis demonstrates the effects of screen time on mental health resilience in the general adolescent population (at least within Generation Z), as opposed to clinical samples. Various implications for public health are discussed.&lt;/p&gt;&lt;h3&gt;List of scientific papers&lt;/h3&gt;&lt;p dir="ltr"&gt;I. &lt;b&gt;Hökby S&lt;/b&gt;, Hadlaczky G ... Carli V. Are Mental Health Effects of Internet Use Attributable to the Web-Based Content or Perceived Consequences of Usage? A Longitudinal Study of European Adolescents? JMIR Ment Health. 2016. 13;3(3):e31. &lt;a href="https://doi.org/10.2196/mental.5925"&gt;https://doi.org/10.2196/mental.5925&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;II. &lt;b&gt;Hökby S,&lt;/b&gt; Westerlund J, Alvarsson J, Carli V, Hadlaczky G. Longitudinal Effects of Screen Time on Depressive Symptoms among Swedish Adolescents: The Moderating and Mediating Role of Coping Engagement Behavior. IJERPH. 2023;20(4):37. &lt;a href="https://doi.org/10.3390/ijerph20043771" rel="noreferrer" target="_blank"&gt;https://doi.org/10.3390/ijerph20043771&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;III. &lt;b&gt;Hökby S.&lt;/b&gt;, et al. Adolescents' screen time displaces multiple sleep pathways and elevates depressive symptoms over twelve months. PLOS Glob Public Health. 2025, 2;5(4):e0004262. &lt;a href="https://doi.org/10.1371/journal.pgph.0004262" rel="noreferrer" target="_blank"&gt;https://doi.org/10.1371/journal.pgph.0004262&lt;/a&gt;&lt;/p&gt;

&lt;p dir="ltr"&gt;&lt;b&gt;Introduction&lt;/b&gt;: Depression and anxiety are the most common causes of illness in Europe, especially among young people, and suicide is the leading cause of death among adolescents in Sweden. The use of digital media is often discussed in relation to mental health. Time recommendations, bans, legislation, and media use guidelines are frequently published-often without clear evidence of their effects or mechanisms of action. This thesis aims to improve our understanding of this phenomenon.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Aim&lt;/b&gt;: Through three studies (I, II, III), this thesis explores the main psychological health mechanisms involved in how leisure screen time may contribute to mental health issues-or simply co-occur with them. It aims to establish a theoretically grounded, empirically supported, and scientifically replicable framework and model for understanding how screen time affects mental health.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Methods&lt;/b&gt;: Longitudinal three-wave psychometric health data were collected over six years in conjunction with two school-cluster randomized trials on psychoeducation and suicide prevention, always administered in classroom settings. Intervention effects were held constant or nullified. Three statistical analyses of screen-health associations were conducted using adolescent health data (N = 4810 from 55 Swedish schools; N = 1544 from 30 schools in seven European countries).&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Analyses&lt;/b&gt;: The primary health outcome was subclinical depression (BDI-II scores), which correlated with anxiety, and stress (DASS-42). All main statistical tests were longitudinal (3-12 months). Study I used hierarchical linear regression of change scores to examine screen activities and their consequences. Study II applied GEE gamma regression to examine moderating effects of coping styles and structural regression to assess their mediating pathways. Study III used preregistered, theory-driven multigroup structural equation modelling to analyze multiple mediation and simultaneous screen-sleep displacements.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Results&lt;/b&gt;: Screen time consistently had a negative impact on various sleep patterns and reduced cognitive coping styles. It was associated with small but adverse health outcomes for the average adolescent. Girls had twice the depression levels of boys and appeared more sensitive to screen-related sleep loss. Long screen times negatively affected Problem-Focused Engagement (PFE) coping, including cognitive restructuring, but not Socio-Emotional coping (EFE) (data collected before the COVID-19 outbreak). Notably, moodiness when screens were inaccessible-i.e., difficulty coping without screens-was the strongest predictor of depression in the first European study.&lt;/p&gt;&lt;p dir="ltr"&gt;&lt;b&gt;Discussion&lt;/b&gt;: The three studies showed that, regardless of gender, longer screen time was associated with sleep loss and/or reduced ability to cope with stress. Independent research confirms that sleep loss further reduces the tendency to use cognitive engagement coping. While causality could not be established, the correct temporal order was identified in the two latter studies, which replicated the initial exploratory findings. The final framework is termed the "Screen Time Displacement Theory of Mental Health" (though not so important). Sleep problems often underlie depression-especially among girls in this sample- where sleep facets (quality, duration, chronotype) mediated 38-57% of the depressive effect over 12 months. Problem-focused coping both mediated and moderated depression in both genders over 12 months (the screen-coping interaction effect equaled maximum +3.4 BDI-II points; p &lt; 0.01). Effective coping styles and consistently sufficient sleep are essential components of psychological and physiological resilience to depressive states, yet most adolescents do not meet conventional sleep or screen time recommendations. This thesis demonstrates the effects of screen time on mental health resilience in the general adolescent population (at least within Generation Z), as opposed to clinical samples. Various implications for public health are discussed.&lt;/p&gt;&lt;h3&gt;List of scientific papers&lt;/h3&gt;&lt;p dir="ltr"&gt;I. &lt;b&gt;Hökby S&lt;/b&gt;, Hadlaczky G ... Carli V. Are Mental Health Effects of Internet Use Attributable to the Web-Based Content or Perceived Consequences of Usage? A Longitudinal Study of European Adolescents? JMIR Ment Health. 2016. 13;3(3):e31. &lt;a href="https://doi.org/10.2196/mental.5925"&gt;https://doi.org/10.2196/mental.5925&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;II. &lt;b&gt;Hökby S,&lt;/b&gt; Westerlund J, Alvarsson J, Carli V, Hadlaczky G. Longitudinal Effects of Screen Time on Depressive Symptoms among Swedish Adolescents: The Moderating and Mediating Role of Coping Engagement Behavior. IJERPH. 2023;20(4):37. &lt;a href="https://doi.org/10.3390/ijerph20043771" rel="noreferrer" target="_blank"&gt;https://doi.org/10.3390/ijerph20043771&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;III. &lt;b&gt;Hökby S.&lt;/b&gt;, et al. Adolescents' screen time displaces multiple sleep pathways and elevates depressive symptoms over twelve months. PLOS Glob Public Health. 2025, 2;5(4):e0004262. &lt;a href="https://doi.org/10.1371/journal.pgph.0004262" rel="noreferrer" target="_blank"&gt;https://doi.org/10.1371/journal.pgph.0004262&lt;/a&gt;&lt;/p&gt;

Leisure screen time, including TV viewing, is associated with increased mortality risk. We estimated the all-cause mortality risk reductions associated with substituting leisure screen time with different discretionary physical activity types, and the change in mortality incidence associated with different substitution scenarios. A total of 423,659 UK Biobank participants, without stroke, myocardial infarction, or cancer history, were followed for 7.6 (1.4) yr, median (interquartile range [IQR]). They reported leisure screen time (TV watching and home computer use) and leisure/home activities, categorized as daily life activities (walking for pleasure, light do-it-yourself [DIY], and heavy DIY) and structured exercise (strenuous sports and other exercises). Isotemporal substitution modeling in Cox regression provided hazard ratios (95% confidence intervals) for all-cause mortality when substituting screen time (30 min·d) with different discretionary activity types of the same duration. Potential impact fractions estimated the proportional change in mortality incidence associated with different substitution scenarios. During 3,202,105 person-years of follow-up, 8928 participants died. Each 30-min·d difference in screen time was associated with lower mortality hazard when modeling substitution of screen time by an equal amount of daily life activities (0.95, 0.94-0.97), as well as structured exercise (0.87, 0.84-0.90). Reallocations from screen time into specific activity subtypes suggested different reductions in mortality hazard: walking for pleasure (0.95, 0.92-0.98), light DIY (0.97, 0.94-1.00), heavy DIY (0.93, 0.90-0.96), strenuous sports (0.87, 0.79-0.95), and other exercises (0.88, 0.84-0.91). The lowest hazard estimates were found when modeling replacement of TV viewing. Potential impact fractions ranged from 4.3% (30-min·d substitution of screen time into light DIY) to 14.9% (TV viewing into strenuous sports). Substantial public health benefits could be gained by replacing small amounts of screen time with daily life activities and structured exercise. Daily life activities may provide feasible screen time alternatives, if structured exercise is initially too ambitious.

Leisure screen time is a key sedentary behavior that may influence various aspects of physical and mental health. This study examines the associations between screen time, meeting physical activity guidelines, self-reported health, and mental health in the Quebec population, considering sex differences. This study uses data from the 2017-2018 Canadian Community Health Survey, a cross-sectional and nationally representative survey. Leisure screen time was categorized: ≤2h/day, &amp;gt;2h-&amp;lt;4h, 4h-&amp;lt;6h, and ≥6h/day. Associations with meeting physical activity guidelines (≥150 min/week of moderate-to-vigorous activity), self-reported health (excellent/very good/good vs. fair/poor), and perceived mental health were analyzed by sex. Higher screen time was associated with a lower likelihood of meeting physical activity guidelines, particularly among men: 76.7% of men with ≥6h/day of screen time did not meet the guidelines, compared to 30.9% of those with ≤2h/day. A similar trend was observed in women, albeit less pronounced. The proportion of men reporting their health status as excellent, very good or good decreased with increasing screen time: 8% of those with ≥6h/day reported such status, compared to 35% among those with ≤2h/day. Similar trends were observed in women. Perceived mental health declined with increasing screen time in both men and women. Among men, the proportion reporting positive mental health decreased from 35% for ≤2h/day to 8% for ≥6h/day. Similar trends were observed in women (36% for ≤2h/day vs. 7% for ≥6h/day), highlighting an inverse relationship between screen time and psychological well-being. Our findings highlight the association between high leisure screen time and poorer self-reported health, lower perceived mental well-being, and reduced adherence to physical activity guidelines in both men and women. These findings emphasize the importance of considering screen time reduction as a modifiable target in public health initiatives promoting overall health. Key messages • High leisure screen time is linked to poorer health and lower physical activity levels in both sexes. • Reducing screen time could be a target for improving well-being in public health strategies.

The COVID-19 pandemic is associated with crucial changes in children’s daily life including their physical activity (PA) and screen time (ST). Among preschool children, the family represents an important factor for sufficient PA levels by being the gatekeeper for PA. Thus, the aim of this study was to investigate the influence of the family environment, specifically SES, parental support, and having siblings on COVID-19-related changes of PA and ST behavior in 317 (170 boys, 147 girls) German preschool children using longitudinal data. Our results indicate a decline in total amount of sports-related PA, an increase in outdoor play, as well as an increase in leisure ST in preschool children. The changes in total amount of PA differed between children with different levels of parental support as well as in dependence on having siblings. Furthermore, levels of outdoor play and ST in preschool children were influenced by environmental factors like having access to their own garden. We conclude that the family environment (parental support as well as physical environment) is highly relevant for PA and ST levels in preschool children. To provide every child with PA opportunities during potential future lockdowns, restriction policies should be adapted and parents need sophisticated information about the importance of their support and thus the PA levels of their children.

Leisure screen time is associated with poor academic achievement; however, the mechanism underlying this relationship is unclear. Chronotypes and emotional/behavioral problems may be linked to this association. This study aimed to examine the associations between leisure screen time, chronotype, emotional/behavioral problems, and academic achievement using mediation analysis. A total of 113 children aged 9–12 years participated in this study. All participants were assessed for leisure screen time, chronotype, emotional/behavioral problems, and academic achievement. Leisure screen time was evaluated using a self-reported questionnaire. Chronotypes were measured using The Japanese Children’s Chronotype Questionnaire, and the morningness/eveningness (M/E) score was calculated. Emotional/behavioral problems were assessed using The Japanese Strengths and Difficulties Questionnaire, and the total difficulties score (TDS) was calculated. Academic achievement was assessed by the homeroom teacher for each of the seven school subjects. Partial correlation analysis adjusted for grade, sex, and sleep duration indicated that leisure screen time was associated with M/E scores and academic achievement (p < 0.05). There was a positive association between M/E score and TDS (p < 0.05) and a negative association between TDS and academic achievement (p < 0.05). A mediation analysis adjusted for grade, sex, and sleep duration was performed. There was a significant total effect of leisure screen time on academic achievement (p < 0.05). Additionally, the M/E score and TDS significantly mediated the association between leisure screen time and academic achievement (p < 0.05). Our findings suggest that the serial path between chronotype and emotional/behavioral problems weakly but significantly mediates the association of leisure screen time with academic achievement.

Physical inactivity and sedentary behavior are associated with higher risks of age-related morbidity and mortality. However, whether they causally contribute to accelerating biological aging has not been fully elucidated. Utilizing the largest available genome-wide association study (GWAS) summary data, we implemented a comprehensive analytical framework to investigate the associations between genetically predicted moderate-to-vigorous leisure-time physical activity (MVPA), leisure screen time (LST), and four epigenetic age acceleration (EAA) measures: HannumAgeAccel, intrinsic HorvathAgeAccel, PhenoAgeAccel, and GrimAgeAccel. Shared genetic backgrounds across these traits were quantified through genetic correlation analysis. Overall and independent associations were assessed through univariable and multivariable Mendelian randomization (MR). A recently developed tissue-partitioned MR approach was further adopted to explore potential tissue-specific pathways that contribute to the observed associations. Among the four EAA measures investigated, consistent results were identified for PhenoAgeAccel and GrimAgeAccel. These two measures were negatively genetically correlated with MVPA (rg = -0.18 to -0.29) and positively genetically correlated with LST (rg = 0.22-0.37). Univariable MR yielded a robust effect of genetically predicted LST on GrimAgeAccel (βIVW = 0.69, p = 1.10 × 10-7), while genetically predicted MVPA (βIVW = -1.02, p = 1.50 × 10-2) and LST (βIVW = 0.37, p = 1.90 × 10-2) showed marginal effects on PhenoAgeAccel. Multivariable MR suggested an independent association between genetically predicted LST and GrimAgeAccel after accounting for MVPA and other important confounders. Tissue-partitioned MR suggested skeletal muscle tissue associated variants to be predominantly responsible for driving the effect of LST on GrimAgeAccel. Findings support sedentary lifestyles as a modifiable risk factor in accelerating epigenetic aging, emphasizing the need for preventive strategies to reduce sedentary screen time for healthy aging.

We examined whether screen time was associated with cardiometabolic disease (CMD) risk factors in young adults. Ninety-five adults (19.9 ± 11.4years) self-reported medical and health behavior history, screen time (television viewing, video games and computer games), and dietary intake. Waist circumference, blood pressure, fasting glucose and lipid levels, cardiorespiratory fitness (VO2peak), and body composition were measured. Total sedentary behavior and moderate-to-vigorous physical activity (MVPA) were measured by accelerometer. On average, leisure screen time (2.0 ± 1.6hday-1) accounted for 24% of total sedentary time (8.4 ± 1.5hday-1). After adjustment for demographics, smoking, sleep duration, total energy intake, total sedentary time and MVPA, a 1-standard deviation increase in leisure screen time was associated with a 26% higher BMI, 29% higher waist circumference, 25% higher fat mass, 23% higher triglyceride, and 24% lower VO2peak (p < 0.05). Our findings suggest that screen time may contribute to the risk of obesity and CMD in young adults.