The “China Youth Development Report” reported that about 30 million children under the age of 17 years in China suffer from various emotional disorders and behavioral problems [1]. Depression is a prevalent concern, with a detection rate of 24.6% among adolescents, of which 7.4% were found to be severe cases. The detection rate of depression is higher among rural and female adolescents compared to their urban and male counterparts, respectively [1]. The consequences of failing to address depressive symptoms can extend into adulthood, leading to illness, disability, and suicide [2].
Researchers have attributed the increase in depression cases among adolescents to excessive Internet use [3, 4]. Compared with adolescents in developed countries, Chinese adolescents are relatively late in popularizing smartphones and using the Internet daily [5]. In the early years, Chinese students are more inclined towards using computers for online gaming, while students in Western countries are more likely to use them for study [5, 6]. However, in recent years, especially after the COVID-19 outbreak, mandatory physical distancing and the loss of offline social connection have resulted in a greater reliance on the Internet among Chinese adolescents [7]. In 2020, their Internet penetration rate was 94.9%. Compared with the figures in 2019, the proportions of more than 30 minutes on weekdays and more than 1 hour on holidays increased by 6.9% and 8.9%, respectively. Taking online classes became the norm, and online social media became a way for them to cope with stress and poor mental health [8, 9]. Overall, the positive function of Internet use is gaining prominence [10-13], and therefore, we doubt whether daily Internet use is a poor behavior for Chinese adolescents. Most studies on Internet use among Chinese adolescents used data from a time when only a minority of young people were online. They focused on Internet addictive behaviors or measured Internet use time as a continuous variable without observing the health effects of short durations or moderate use [14-17].
Chinese adolescents use various Internet devices, including smartphones, tablets, desktops, and laptops. The most popular purpose of using the Internet is learning, listening to music, watching video clips, gaming, and online communication [8, 9]. Research suggests that the relationship between Internet use time and depression varies by device and online activity [17-22]. However, they did not consider the impact of short-duration or moderate use of various devices and some popular activities (e.g., posting Moments on WeChat). Most importantly, the previous studies did not further explore whether the relationships between different Internet device use and activities and adolescent depression varied by individual characteristics.
Previous research suggests that the relationship between Internet use and depression could depend on gender and geographic location [15, 20, 23, 24]. One critical reason is the gender and geographical location differences in access to digital technologies (the first-level digital divide) and the extent and pattern of use of digital technologies (the second-level digital divide) among adolescents [25, 26]. Girls and adolescents from areas of low socioeconomic resources often have less access to technology and the Internet [8, 9]. Digital inequalities have real consequences on the daily lives of children and young people and may impact their development across a wide range of areas [27]. Few studies have been conducted on whether digital inequalities can be detrimental or beneficial to the mental health of Chinese girls or adolescents from areas of less socioeconomic resources. This study will use data from a national survey collected after the outbreak of COVID-19 to explore the relationships between different Internet device use and activities and depression among adolescents across gender and geographical location.
Relationship between Internet use time and depression
Researchers have proposed the hypothesis of displacement and stimulation [10]. The displacement hypothesis assumes that the negative impact of Internet use on mental health manifests itself primarily as time displacement and social interaction displacement. Internet activity is primarily conducted in solitude and often recreationally. It displaces individuals in more meaningful daily activities such as sleep, physical exercise, school attendance, and offline interactions [10, 28-30]. Adolescents who spend large amounts of time on the Internet may have conflicts with their parents and guardians and have an increased risk of developing mood disorders, including loneliness, distress, anger, loss of control, and social withdrawal [31]. Moreover, when used for communication purposes, online social interaction is primarily with weak relationships rather than with close family and friends, and thus has little benefit to the psychosocial well-being of individuals [32]. Meanwhile, the time spent online displaces face-to-face social engagement, reducing the quality of social relationships. The stimulation hypothesis holds that Internet use may serve as a coping mechanism for depressive feelings and can stimulate well-being by helping people avoid boredom and cope with a lack of stimuli in everyday situations, making them aware of interesting events, enhancing social connectedness, providing social support, and enabling individuals to express thoughts and feelings [10-12].
Research on adolescents in developed countries suggests an inconsistent relationship between daily Internet use time and depression. Some studies support the displacement hypothesis, suggesting that daily Internet use time or frequency is positively associated with the risk of depression [15, 33, 34]. Some studies found a nonlinear U-shaped relationship [35, 36]. For instance, Moreno and colleagues reported that compared to low daily use (for example, <30 minutes), adolescents who use the Internet regularly (30 minutes to 3 hours) are at a lower health risk, while those who use the Internet excessively (>3 hours) are at high risk [35].
Research on Chinese adolescents also examined the effect of Internet use time on the risk of depression among Chinese adolescents and found that adolescents with longer online durations reported higher levels of depression [15, 16]. However, they generally focused on long-duration Internet use and did not show the health effects of low or moderate daily use. Furthermore, the data used in most of these studies were collected before COVID-19. Digital technologies provided various benefits in addressing people’s mental health concerns during COVID-19 [37]. Affected by the epidemic, children and young people became dependent on the Internet for learning, entertainment, and social interaction [8, 9]. When adolescents use the Internet more for learning and spend less time on recreational activities, it can promote the quality of their relationships with their parents and teachers and benefit their mental health. This means that the relationship between daily Internet use time and depression may no longer be a positive linear relationship, which needs to be re-examined.
The associations of diverse Internet device use and activities with depression: Differences in gender and geographical location
Researchers suggest that measuring Internet use should consider the frequency of use, variation/range of use, and autonomy of use [38, 39]. Therefore, we measured the time spent on different Internet devices that can reflect the autonomy of use. Internet activities were measured by combining the frequency and variation of use, expressed as the frequency adolescents engaged in online learning, gaming, watching short video clips, shopping, and posting WeChat Moments.
Compared to desktop devices, mobile devices are more portable and user-friendly [40]. They are more effective in improving adolescents’ access to information, enhancing their learning and knowledge, helping to avoid boredom, adding fun and enjoyment to daily life, and providing more opportunities to interact with family and friends [41]. However, adolescents are easily distracted by the plethora of choices provided by smartphones [17, 42], which makes adolescents more likely to experience a range of adverse outcomes, such as sleep deprivation, anxiety, mood disorders and reduced academic performance [43, 44]. A study by Ma and Gu, which can be seen as a precursor to this study, simultaneously investigated the effect of mobile and desktop device use on the risk of depression among Chinese adolescents [17]. However, as they measured time consumption on different devices as a continuous variable, we still cannot determine which specific combination of durations on various devices could help reduce the risk of depression.
Furthermore, research suggests that different Internet use creates unequal effects on adolescent mental health [17-22]. For instance, Ma and Gu found that adolescents who used the Internet for gaming, shopping, and viewing short videos had a higher risk of depression, while online learning frequency was not significantly linked to their depression risk [17]. They did not examine the health effect of using chat apps, such as WeChat. WeChat Moments is the most popular platform on which people can convey their current status to all or a selected group of contacts by sharing feelings, photos, and short videos of their daily lives. Meanwhile, users can also easily view the latest status of all their contacts. Some researchers have claimed that status updates, an active form of social networking sites (SNS) use, can positively predict adolescents’ well-being, as they can enhance connections with family and friends, thereby increasing their social support perceptions [45, 46]. However, when users post WeChat Moments, they will inevitably browse the statuses posted by their friends, which is a passive form of SNS use. As per social comparison theory, users have an innate drive to compare themselves with their friends. When engaged in upward comparison behaviors (i.e., comparing with someone they think is better), they may develop various adverse outcomes attributable to their reluctance to solicit help when needed [45, 47, 48]. These complicated features lead to an inconstant relationship between the behavior of posting WeChat Moments and depression risk in Chinese adolescents. Furthermore, during the epidemic, the positive and negative effects of posting WeChat Moments may be strengthened because WeChat Moments is a critical channel for gaining information, seeking help, and emotional release. Therefore, this relationship may become more complex. Prior studies on Chinese teenagers concentrated on the health consequences of social networking addiction and did not specifically analyze the effect of WeChat Moments [49, 50].
Gender differences
Gender schema theory and social role theory posit that boys and girls develop gender-appropriate cognitive schemas in early childhood through social learning, which largely influence individuals’ thought processes and behaviors, enabling them to perform different social roles depending on the specific social and cultural environment [51]. Research reported that women were less likely to use the Internet and had less access to opportunities for Internet devices, device diversity, and peripheral diversity [25, 52]. Men were found to have a more confident attitude towards technology use and were more motivated to acquire digital knowledge than women [53], thus, they develop less digital anxiety and have higher self-efficacy [54]. These imply that when forced to use the Internet frequently, compared to boys, girls may have a heavier psychological burden. Some studies have confirmed that among those with high levels of Internet use, women were at a higher risk of depression than men [15, 55, 56]. However, existing research does not provide an answer to whether both desktop and mobile device use would pose a higher threat to girls’ mental health and which combinations of Internet device use are associated with a lower risk of depression for boys and girls.
Studies have found that males prefer to use the Internet for information, games, and entertainment, while females are more likely to use communication tools [44, 57, 58]. Research on adolescents in developed countries suggests that girls are more deeply affected by certain screen activities, such as listening to music and using the Internet, and are at a higher risk of depression compared to boys [20, 21]. However, the relationships between playing electronic games and adolescent mental health were found to not vary by gender [21]. Due to the differences in online activities between adolescents in China and developed countries [58, 59], we cannot determine whether various online activities, such as online learning, gaming, watching short videos, shopping, and posting WeChat Moments, lead to a higher risk of depression in Chinese girls than in boys.
Geographical location differences
The disparities in the levels of socioeconomic development in different administrative divisions are replicated in the digital world. Schools in underdeveloped regions generally lag regarding information and communication technology (ICT) resources and teacher capital, such as teachers’ limited beliefs about technology. This study divided geographical locations into four tiers: provincial capital, prefecture, county, and rural area, rather than just urban and rural areas.
Urban adolescents use multiple devices, with a particular focus on applications such as search engines, social networking sites, news, and shopping, which can help them accumulate more capital and provide them with opportunities and resources to improve their learning and create friendships and social groups. In contrast, rural adolescents primarily use mobile phones for their Internet needs, and they prefer leisure and entertainment applications like short videos, animations, and comics for instant gratification [8, 9]. Internet use has both positive and negative effects on individuals’ mental health [10-12, 29, 30]. This means that the impact patterns of Internet use on urban and rural adolescents’ depression may be different. To our knowledge, only two studies compared urban-rural differences in the impact of time spent using the Internet on Chinese adolescents’ mental health or well-being [15, 24]. Zhou and Ding found that prolonged use can widen the depression gap between adolescents in developed and underdeveloped regions [15], while Long and Han found that Internet use can help narrow the subjective well-being gap between urban and rural adolescents [24]. They did not distinguish the desktop and mobile device use and employed data collected before the epidemic or earlier.
Furthermore, only Long and Han differentiated some online activities, including learning, socializing, and entertainment [24]. They found that online learning and entertainment were positively associated with the subjective well-being of rural but not urban adolescents. It can be inferred that using the Internet for learning and entertainment may be beneficial in reducing the risk of depression among rural adolescents, which remains to be verified. Since they did not distinguish various popular entertainment activities, the respective effects of frequent participation in watching short videos, gaming, posting WeChat Moments, and shopping on adolescent depression in rural areas and different tiers of cities are uncertain [15, 24].
The current study
The current study serves three purposes. First, using data collected during the pandemic, this study re-examined the relationship between Internet use time and the risk of depression in Chinese adolescents, taking into account the effects of low and moderate daily Internet use. Second, it explored the association of different time durations on mobile and desktop devices with adolescent depression; and the relationship between the frequency of online activities (primarily posting WeChat Moments) and depression. Finally, this study further investigated whether there are gender and location differences in the relationships between different Internet device use and online activities and depression, thus discussing the impact of digital inequalities on adolescent mental health.