Children's Increased Screen Time During the Pandemic Is Now the New Normal

The restrictions during the COVID-19 pandemic were widespread and lengthy and had consequences for the daily lives of children, adolescents and adults worldwide. While the restrictions placed on children and adolescents were relatively mild in Sweden, they still seem to have had a lasting impact on some aspects of daily life.

A repeated cross-sectional population-based study by Kägi-Braun et al., published in Acta Paediatrica, focused on physical activity and screen time trends in Swedish children and adolescents aged 4–17 years of age. The Generation Pep Study, which covered the period 2018–2023, showed that the increased sedentary screen time seen outside school during the pandemic remained at that new higher level after it ended [1]. This corroborated similar results from longitudinal studies of Swedish adolescents published in 2023: Berggren et al., Helgadóttir et al. and Nutley et al. [2-4] It also extended this finding to the general population. The advantage of using a large representative sample of more than 50,000 individuals is that the findings covered age-specific behaviours in more detail. It also means they are more likely to be generalisable. Furthermore, a subset of the sample used accelerometers to provide objective measures of physical activity and more specific information on their digital use. While the overall trend was that time spent on digital screens increased during and after the pandemic, the subsample revealed that most of this was on social media.

While the content and context of social and other digital media use matters, increased screen time at a population level is of concern for several reasons. A systematic review published by Santos et al. in 2023 showed that excessive digital media use had negative associations with mental and physical health outcomes [5]. It also increased the risk of addictive use and displaced health promoting behaviours, such as sleep and exercise. Digital media is known to affect children in different ways, depending on both the characteristics of the child and the context that it is used in. However, the overall time spent on it does need to be monitored, as there are only a certain number of hours available in a day. Increasing sedentary time spent on digital media will lead to less time spent on factors like sleep, schoolwork and physical activity. This is known as media displacement effects. So what happened to children and young people, at the population level, during the pandemic and what do we need to do to address this?

The pandemic posed an interesting time-based experiment, as the daily activities of some age groups were greatly affected by studying or working from home. This eliminated travelling time and the physical activity associated with that. This was reflected in the study by Kägi-Braun [1] and the other longitudinal samples mentioned above. These reported less physical activity in the adolescents affected by the pandemic restrictions, but not in the younger age groups whose schools stayed open. However, the pandemic did not seem to have a clear negative lasting impact on Swedish adolescents, as their activity levels recovered after the pandemic. While this could be regarded as a positive result, a pooled analysis of 1.6 million adolescents by Guthold et al. [6] reported that only 20% met the World Health Organisation (WHO) recommendations for physical activity before the pandemic. The WHO has reported that regular physical activity was positively associated with cardiorespiratory and musculoskeletal fitness, cardiometabolic health, bone health and cognitive function. Poitras et al. reported that this had a particular impact during development and was of utmost importance in adolescents [7]. This can only be addressed if there is an accurate depiction of the different physical activity levels of children and adolescents, namely sedentary behaviours and low and high intensity activity, and how they relate to health outcomes.

While many studies rely on self-reported data, the accuracy can be greatly improved by using accelerometers and objectively tracking different intensity levels of physical activity and sedentary behaviours. That was what Kägi-Braun did in a sub-sample of the study published in Acta Paediatrica [1]. The results from 435 children indicated that they spent an average of about 5 h a day engaged in any type of physical activity and 9 h in sedentary activities. Older children recorded less physical activity and more sedentary time than the younger children. Wang et al. reported that lengthy sedentary periods were associated with increased risks of obesity, cardiovascular and metabolic disease, poor skeletal and muscle development and mental health problems [8]. This means that the current average levels of sedentary time risk negative health effects in many children.

Many factors over the past century can explain how societies have adopted increasingly sedentary lifestyles. However, the worldwide adoption of handheld digital media in the past decade, including by young children, is likely to have exacerbated these habits on a scale that has not been seen before. The WHO previously just focused its recommendations on physical activity levels, but has now added recommendations on minimising sedentary behaviours due to the negative health impacts of prolonged inactivity. Teasing out the effects of sedentary behaviour and the effects of different levels of physical activity on physical and mental health outcomes is very relevant to guiding more specific interventions. For instance, the relation between the absolute time spent on sedentary screen time may not be linearly associated with time spent in physical movement for the effects on health. It has been suggested that high-intensity training can partially mitigate the negative effects of excessive sedentary time and provide a larger investment in health than low-intensity training [8]. In other words, individuals who regularly engage in high-intensity training may be able to tolerate more sedentary time than individuals who do not [8].

Furthermore, there may also be age-specific effects that warrant different approaches when it comes to promoting physical activity. Cooper et al. reported that a decline of around 4% in physical activity levels may be expected for each additional year of development after 5 years of age [9]. Simply removing screens may not automatically increase physical activity for all, but it may work for some age groups. Kägi-Braun et al. [1] reported that the youngest children, aged 4–6 years, showed an increase in physical activity during the pandemic. This was probably due to more outdoor play and indicates that children have a natural drive to be physically active if they are given the opportunity. Pedersen et al. [10] carried out a randomised controlled study where half of the families reduced their screen time to approximately 30 min per day. The children in the intervention group increased their physical activity by an average of 45 min per day, compared to the control group. Another study on general systematic efforts reported that children attending schools that promoted health and had a physical activity policy had increased levels of physical activity compared with children in schools lacking such polices [11]. Meanwhile, Nyberg et al. [12] showed additional benefits if schools had a mobile-free policy during break times in terms of physical activity levels. In other words, promoting health behaviours by decreasing access to screens and encouraging physical activity in environments where children spend their days seemed to be successful in addressing risk behaviours at a group level.

More targeted interventions to promote physical activity may also be warranted. Forte et al. have stated that it may be beneficial to direct specific efforts towards breaking these patterns in adolescent girls, because they typically report spending more time on social media [13]. The same authors reported that girls displayed higher levels of symptoms and mental distress, less physical activity and more sedentary behaviours. The data from the accelerometers used by Kägi-Braun [1] revealed that boys generally moved more intensely than girls, but were equally sedentary. Furthermore, children from lower socioeconomic backgrounds were more sedentary, and children with obesity had lower levels of physical activity. These findings can guide efforts to support vulnerable subgroups, in particular, into more health promoting behaviours.

A number of lifestyle factors affect the physical and mental health of children and adolescents. Although researchers are still disentangling individual effects from different types of screen-based activities, the protective effects of repeated physical activity are quite clear [7, 8]. Physical activity levels due to the pandemic restrictions may have returned to pre-pandemic levels in this Swedish sample, but sedentary screen time has not. This means that the increased pandemic levels have become the new normal.

Displacement effects from increased sedentary screen time may impact a number of different protective factors, such as physical activity, schoolwork, sleep duration and/or simple brain rest. This means that children can face different levels of increased risks of stress, physical and mental health challenges. There is, therefore, a greater need for population-based studies like the one by Kägi-Braun et al. [1], which used objective measurements of physical activity, and preferably also screen time. This would increase our understanding of the subgroups that require targeted efforts. These large-scale studies would also allow us to further explore the complex nature between the different aspects of physical activity, digital use and health outcomes. These would include how their relationships differ between age groups, genders and other relevant subgroups. This knowledge is greatly needed so that all levels of society can support children and adolescents more effectively going forward. The study by Kägi-Braun et al. [1], published in Acta Paediatrica, contributes valuable information to the ongoing research in this area.

The author declares no conflicts of interest.