Children are increasingly using digital media devices for leisure and learning purposes. Instead of watching TV, children use a combination of live, recorded playback, and broadcaster-on-demand services. Therefore, presently, children use digital media such as smart devices, tablet personal computers (PCs), and PCs more than they do TV [1].

While educational television, such as Sesame Street or Blue’s Clues, has been reported to have a positive effect on children’s learning and socio-emotional and language development [2,3], excessive exposure to non-educational digital media has been shown to have a negative effect on children’s behavior, cognition, and emotional health [4]. The negative effects include decreased inhibitory control [5], hyperactivity [6,7], sleep problems [8], and decreased attention [9], all of which may result in poor academic performance. In addition, excessive digital media use has been reported to be associated with depression and suicidal thoughts among adolescents [10]. However, Shutzman and Gershy [11] highlight the need to treat digital media use and problematic digital media use as distinct constructs. Therefore, understanding the extent and pattern of children’s digital media use is important for establishing strategies to reduce problematic digital media use.

Even before the pandemic, children’s digital device use time had tripled from 2013 to 2017; coronavirus disease-2019 (COVID-19) has further increased it. School closures due to COVID-19 have had a significant impact on student learning styles worldwide [12]. During the pandemic, online learning methods, such as educational apps, video lectures, and YouTube, were used for elementary school students [13]. Additionally, children’s use of social networks increased for ongoing interactions with peers and relatives; consequently, they spent more time using smartphones, tablets, and computers [14,15]. Particularly, during the COVID-19 emergency, some people relied on the Internet and social media to alleviate pandemic-related anxiety. Apropos this, excessive media use has caused children to become less interested in real life and to focus only on what is happening on the Internet [16].

Research suggests that excessive media use over long periods of time causes more negative problems for children than positive ones. However, few studies have specifically investigated the amount of time spent on digital devices since the outbreak of COVID-19. Moreover, most of the existing studies on screen time have been cross-sectional. While previous studies have focused on adolescents or adults, this study is a longitudinal observation of elementary school students aged 8-11 years, before and after the COVID-19 pandemic. This study aimed to test the hypothesis that screen time has increased during the COVID-19 pandemic by examining the changes in screen time from the pre-pandemic period (2018- 2019) to the post-pandemic period (2020-2021). Therefore, in this study, we investigated the longitudinal usage time of PCs, tablet PCs, and smartphones among elementary school students aged 8-11 years, compared the differences between weekdays and weekends, and analyzed the differences before and after the pandemic.

This study examined the longitudinal trends in media device use by young children aged 8-11 years in South Korea from 2018 to 2021. Our findings show that the time spent on media device use increased significantly from Wave 4 to Wave 7 from before to during the COVID-19 pandemic period, and the most striking trend in the categories of devices was on the PC which showed the greatest increase. This increase showed a significant causal relationship even after adjusting for covariates such as children’s age, household income, and parental education levels.

These findings are consistent with those of previous studies on media exposure among young children. A recent systematic review reported increases in children and adolescents’ screen time before and during the initial COVID-19 lockdown [19], although the majority of the studies were cross-sectional. Only eight studies collected data prospectively; none examined the types of screen time or whether the observed increase continued as the pandemic spread. During the COVID-19 pandemic, more than 78% caregivers reported that their children were watching media such as YouTube, and 49% reported that their children were spending more than 6 hours online per day [20]. Another study reported an increase in total screen time among children aged 4-12 years across the US from before to during the COVID-19 pandemic, which persisted as the pandemic progressed [21]; however, the study had a relatively short pre-pandemic follow-up period. Ofcom, the UK’s independent communications regulator, surveyed children aged 3-17 years regarding their media use and attitudes [1], and Lee et al. [22] reported the duration of media use in children aged 2-5 years in South Korea.

There is already substantial evidence suggesting that the use of smart devices increases mental health issues and problematic behaviors in children. Kim et al. [23] suggested that children’s smartphone screen time affected their problematic behaviors during the COVID-19 pandemic. In addition, Liu et al. [24] found that the longer the media usage time, the more severe the depression in children between the ages of 5 and 18 years who used digital media for more than 2 hours a day. The finding that children experience a lack of sleep before depression and suicidal thoughts appear [25], suggests that using digital media at night can be a mediating factor that links depressive symptoms and suicidal thoughts. Additionally, excessive use of digital media can lead to Internet addiction, which occurs more often in children and adolescents with high levels of anxiety, helplessness, negative thinking, and impaired social functioning [24,26]. Our research revealed that increases in screen time continued for over 2 years after the pandemic ended, even after many restrictions were lifted. This implies that more precise clinical guidelines and policies may be required to support parents and their children in reducing screen time both during and after the COVID-19 pandemic.

Meanwhile, through covariate analysis of children’s screen time, we discovered that higher maternal education levels were significantly associated with a decrease in screen time. These findings are consistent with those of previous studies conducted before the pandemic period. Maternal education is inversely associated with preschoolers’ television viewing time [27], and the frequency of tablet use and ownership of mobile devices was inversely related to household income and maternal educational level [28]. This suggests that the higher a mother’s educational level, the more likely she is to prevent her child from being indiscriminately exposed to smart devices; hence, the supervision of children’s access to mobile devices increases with parents’ higher educational level. In contrast, paternal education level did not show a significant correlation with smart device usage time. This discrepancy may be attributed to the greater physical and emotional presence that mothers typically maintain within the household [29,30]. Although this study did not investigate whether the main caregiver was the mother or the father, future research should examine whether the results vary depending on the primary caregiver, considering the growing expectation of fathers’ roles as caregivers in Korea. In addition, inverse socioeconomic gradients in children’s television viewing time were found from the preschool period to the late school period [31], and children of parents with higher education levels had a smaller increase in screen time [32].

This study has several strengths. Using a common protocol to evaluate children’s media use across time and cohorts, the K-CURE study was uniquely able to prospectively measure changes in screen time from the pre-pandemic period to during the pandemic in South Korea. A large majority of the previous research on screen time has been cross-sectional. This study is a longitudinal observation carried out on elementary school students aged 8-11 years before and after the COVID-19 pandemic, whereas earlier research was primarily concentrated on adolescents or adults. One of the limitations of this study is that because remote schooling was uncommon prior to the pandemic, the survey did not evaluate whether children were receiving their education remotely at the time it was conducted, nor did it examine whether screen time was being utilized for this purpose. This may have affected how parents reported their educational screen time during the pandemic period. Furthermore, because parent-reported screen time tends to overestimate or underestimate actual usage, it is possible that parents inaccurately reported their children’s media use, even though it correlates with objectively measured usage. Additionally, as mentioned previously, this study only investigated the amount of smart device usage and did not examine the purposes for which these devices were used. Therefore, further research and analysis of the content accessed by children using these devices is necessary. Moreover, we acknowledge that this study included a single cohort; therefore, it may not be representative of the general Asian population. However, in conclusion, against the backdrop of existing knowledge that the use of smart devices has a negative impact on children’s mental health, our study has been able to ascertain that COVID-19 has had a significant influence on the smart device usage time of elementary school children. We anticipate that further studies will be conducted to explore the purposes and contents of smart device usage.