Introduction

Worldwide, 13.4% of children and adolescents experience mental health disorders [1], indicating that adolescents are at high risk. In fact, 70% of mental illnesses start in early ages [2], and many persist into adulthood [3]. These statistics are alarming given that mental disorders contribute 21.8% of the total burden of disease in high-income countries among children and adolescents aged 0–14 years [4] and can reduce life expectancy by 20 years [5], thus leading to premature mortality.

Sedentary behaviour is defined as any waking activities that result in an energy expenditure ≤ 1.5 metabolic equivalents (METs) while in either a sitting, lying or reclining posture [6]. It includes most sitting-based activities (e.g. reading, eating, listening to music, drawing, etc.) and screen-based leisure time activities (e.g. TV viewing, playing video games, use of computers, cellular phones, tablets and social media) [7,8,9]. Sedentary behaviour can be measured objectively using accelerometers, which offer an accurate measurement of total sedentary time, and subjectively using questionnaires and diaries which provide detailed information on the quality, context and type of sedentary behaviour [10, 11]. Sedentary behaviour, primarily in the form of screen use among children and adolescents, has increased dramatically in the past decade with the advent of mobile technology, with the majority of youth spending large proportions of the day (6–8 h) in this type of sedentary activity [12, 13].

It has been recognised that sedentary behaviour has detrimental health effects, including adverse cardiometabolic health outcomes, morbidity and premature mortality [14,15,16,17]. Indeed, high levels of sedentary behaviours are correlated with many adverse health outcomes in children and adolescents, including physical and mental well-being [18], elevated body mass index (BMI) [19,20,21], cardiometabolic function [21, 22] and cognitive development [20]. In this context, Canadian and international guidelines established recommendations to limit the time spent engaged in sedentary pursuits [23,24,25,26]. For example, the Canadian 24-h movement guidelines for children and adolescents discourage screen time for children under 2 years old and suggest no more than 1 h daily for children 2–4 years and no more than 2 h for those aged 5–17 years old [27]. Despite these recommendations, the vast majority of children and adolescents do not meet these guidelines and engage in high levels of screen time, with many accruing between 6 and 8 h/day [9, 12, 13, 28,29,30,31,32].

Surprisingly, findings from a recent systematic review found limited evidence to show that objectively measured sedentary behaviour has a negative impact on mental health [33]. However, objectively measured sedentary behaviour combines screen time and many non-screen sedentary behaviours such as reading, homework, listening to music and other sedentary hobbies, so the effects of screen time on mental health have not been adequately isolated. There are many inherent aspects of spending long periods engaged in screen use that can lead to poor mental health, including feelings of social isolation or withdrawal, exposure to unrealistic ideals of beauty, unhealthy social comparisons, sleep reduction and cyberbullying [22, 34,35,36,37]. Moreover, there is evidence that different types of screen use may have different impacts on health [38], indicating that the type of screen matters, although this has not been well studied. Research has indicated that digital media users have different needs that impact the selection and the preference of media [39]. According to the differential-susceptibility model proposed by Valkenburg and Peter [40], the effects of media are dependent on a complex combination of cognitive (effort invested), physiological (stimulation received), behavioural (frequency/duration of use) and personality characteristics, which collectively lead individual differences in susceptibility of harmful effects of media consumption [40].

Therefore, given the high prevalence of screen time and mental health problems among children and adolescents and their significant economic [41, 42] and health impact they pose [43, 44], it is timely to better understand how screen time among children and adolescents is related to important mental health outcomes, such as anxiety, depression, body image and psychological well-being. Accordingly, this narrative review aimed to synthesise research in this area, including research using both cross-sectional and longitudinal designs to establish an evidence base that can inform policy, practice and research regarding the psychological impacts that screen use has on children and adolescents.

Methods

Electronic databases of Medline/PubMed, PsychINFO and Google Scholar were searched on December 2019 for articles published in the last 5 years. The search mainly focused on the association between recreational screen time sedentary behaviour and mental health outcomes in children and adolescents including anxiety, depression, psychological and psychosocial well-being and body image concerns. Then the articles’ titles and abstracts were screened, and full text of potentially relevant articles were retrieved according to eligibility criteria. Information was extracted from each article and summarised in tables categorised by to the study outcomes. A total of 60 articles met the inclusion criteria. Included studies were heterogeneous and varied in terms of the screen time activities including age, sample size and outcome measures.

Cross-sectional Studies on the Association Between Screen Time and Depressive Symptoms

Depression and anxiety are considered to be among the leading causes of illness, disability and burden in youth according to the World Health Organization [45, 46]. The prevalence of depression increased by 18% [47] between 2005 and 2015, and up to 20% of children and adolescents to meet criteria for anxiety disorders [48]. This is highly concerning especially with emerging research indicating that the onset of depression and anxiety is occurring at younger ages [49,50,51].

Many cross-sectional studies [36, 52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73] (Table 1) have examined the relationship between screen time and symptoms of depression and/or anxiety among children and adolescents. Out of 23 cross-sectional studies, the majority of studies (n = 17) showed that high exposure to at least one type of screen use was associated with more severe depression and/or anxiety symptoms [36, 52, 53, 57, 59,60,61,62,63,64, 67•, 68,69,70,71,72,73], while only a few studies reported negative associations [58] or mixed associations based on gender [54, 55, 56•, 65, 66]. Research on preschooler’s screen time and mental health such as depression and anxiety is lacking.

Table 1 Characteristics of studies on depression and anxiety
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In cross-sectional studies, almost all types of screen use were significantly associated with a higher level of depressive symptoms among young people, especially adolescents, with aggregated time spent engaged in television, computer and mobile phone use showing the strongest associations, indicating an additive effect of screen use. For example, one of the largest cross-sectional studies (n = 9702) [53] on adolescents found that screen use was associated with an increased odds of moderate and severe symptoms of depression and anxiety. These results were similar to other large cross-sectional studies [60, 63]. Maras et al. demonstrated that higher levels of screen time, as measured by an aggregate of TV viewing, recreational computer use and video gaming, were associated with more severe symptoms of depression and anxiety among the youth [60], consistent with cross-sectional findings from other studies among children and adolescents [52, 61, 75, 76]. Associations with emotional distress may differ by screen type, as leisure computer use was more highly associated with anxiety and depression outcomes than television viewing in some studies [52, 60], but cross-sectional findings from a longitudinal study found that high levels of TV viewing and not recreational computer use were more strongly associated with depressive symptoms in adolescents and children [74].

Internet-based video gaming has recently become a popular activity among adolescents, especially males, making it an important type of sedentary behaviour to investigate. A recent study on 578 adolescents reported that high use of internet video gaming was associated with more severe anxiety and depression among adolescents, with males being more affected than females [65]. These results are consistent with other studies showing a strong association between computer games and symptoms of depression [52, 60]. However, a recent European study on gaming among school children between 6 and 11 years found that gaming was not significantly associated with self-reported mental health problems such as depression and anxiety [58]. The conflicting findings may be due, in part, to differences in “dose” of video gaming and age, as the studies with adolescents reported much higher usage of gaming compared with those involving pre-adolescent samples.

In addition to online video gaming, new digital media like social media networking sites have also been recognised to be associated with mental health issues like depression and/or anxiety [36, 56•, 67•, 68,69,70,71,72,73]. A recent nationally representative study [56•] reported that adolescents who frequently use social media were more likely to have high levels of depressive symptoms, with stronger correlations reported among females. The association between social networking sites (SNS), psychological distress and suicide attempts was found to be indirect and mediated by cyberbullying victimisation in a large study (N = 5126) of adolescents (aged 11–20 years) [36]. Insomnia was another mediating factor reported by Li et al., who found a positive association between Facebook addiction and depression among 1015 Chinese adolescents [72]. Furthermore, another cross-sectional study indicated that both active and passive use of Facebook were associated with an increased depressed mood. However, this association was influenced by gender where girls who use Facebook passively and boys who use Facebook actively in a public setting were more likely to develop depression. Also, this study indicated that perceived social support mediated the relationship between social media and depression [69]. The number of social media accounts and the frequency of checking were also found to be additional factors that impact the association between social media and depression and anxiety according to data from parents [70]. These factors and mediators require further investigation in future research.

Concerning the age group, the majority of studies assessed screen use and depression among adolescents, or combined children and adolescents without examining these populations separately, so associations in children are unclear. The greater inquiry in adolescents might be attributed to adolescents reporting higher screen use than children [89] or being more prone to experiencing depression than children [90].

Longitudinal Studies on Screen Use and Anxiety/Depressive Symptoms

Several longitudinal studies examined the association between screen time and depression and anxiety among children and adolescents [74,75,76,77,78,79,80,81,82,83,84,85,86,87,88] (Table 1). Some recent studies were in line with cross-sectional ones and found a positive association between screen use, depression [74, 77•] and anxiety among adolescents [85, 88]. For example, a longitudinal study done on 3826 adolescents found a time-varying relationship between social media, television and depressive symptoms [77•]. Each additional hour spent on social media usage in a given year was linked to a 0.41-unit increase in depressive symptoms for that same year, indicating a dose–response relationship. Also, a similar within-person association was found with television watching [77•]. Furthermore, a large longitudinal study with 6595 adolescents aged 12 to 15 years old reported that spending more than 3 h daily on social media significantly increased the risk for mental health problems, particularly internalising problems such as depression and anxiety [85]. While 8 longitudinal studies [74, 77•, 79, 82, 85,86,87,88] found an association between some types of screen activities and depression and/or anxiety, other studies found little [78, 80, 81] or no evidence [75, 76, 83] that screen time is longitudinally associated with depression and/or anxiety. For example, a longitudinal study involving children and adolescents that examined the association between television watching and mental health indicated no significant association [83].

Interestingly, many cross-sectional and longitudinal studies found that the association between screen time and depression [54, 55, 56•] and anxiety [84•] differed by gender. Many studies found that females with high levels of screen time use reported the highest level of depressive symptoms, while weaker or even no associations were found in males [54, 55]. Another study found higher symptoms of anxiety with playing video games among girls and lower symptoms among boys [84•] which contradicts the findings from Wang et al. [65] who reported that high online video game use was related to higher symptoms of depression and anxiety among males. It should be noted that the sample of youth from the study by Wang et al. engaged significantly in more time of online gaming, thereby highlighting that video gaming may be especially psychologically harmful with excessive use.

The difference in results and clear gender differences in longitudinal studies might be related to diverse types of screen use, dose, age and variation in the baseline level of anxiety and depression among adolescents. For example, a study by Kelly et al. in 2018 involved 10,904 adolescents, indicating that females spent a high proportion of their time on social media and that the magnitude of association between social media use and depressive symptoms was larger for females than for males [56•], consistent with the findings in similar studies and reviews [87••, 91]. Research has indicated that high social media use may confer an increased risk of depression in adolescent females due to interference in sleep habits [37], exposure to teasing or cyberbullying or unrealistic beauty ideals leading to unfavourable social comparisons and low self-esteem [92]. These gender differences might also be related, in part, to the higher baseline levels of anxiety/depression among adolescent females than males [93] as the prevalence of depression and anxiety after puberty is twice as high for females compared with males [94], as well as a higher prevalence of social media use among adolescent girls.

Although consistent gender differences emerged for social media use, a recent longitudinal study on video games and anxiety among older adolescents showed that while moderate use of video gaming was associated with higher anxiety symptoms among females, this was not the case in males [84•]. While the reason is still unclear, the authors hypothesise that boys may enjoy the social interaction and sense of competition between players more than girls. On the other hand, it is noteworthy that the degree of internet usage or video game “dose” may have an important impact on affective symptoms, as youth with extensive screen exposure in the form of internet use/video gaming exhibited significantly more mental health issues than those with low usage, regardless of gender [95].

Very few studies have examined reciprocal relationships between screen time and depression and anxiety symptoms among children and adolescents. However, a large longitudinal study among adolescents showed a reciprocal relationship between computer and videogame usage and increased level of generalised anxiety disorders [88]. That is, youth with emotional distress characterised by anxiety may spend more time indoors and engage in various forms of screen time as a way of coping, and these media activities may further exacerbate their psychological distress, thereby creating a vicious cycle.

In summary, there is strong cross-sectional and moderate longitudinal evidence for an association between screen time and depressive symptoms among children and adolescents, but associations differ by age, type of screen use, gender and other moderators. Most of the studies focused on depressive symptoms, so further longitudinal studies are warranted to better understand the association between different types of screen time and anxiety.

Cross-sectional Studies on Screen Time and Psychological Well-Being

Psychological well-being refers to satisfaction with life and experiencing positive emotions [96], including positive self-perceptions and positive relationships [97]. Research has linked psychological well-being with academic performance [98], physical health [99] and mental health. Thus, it is essential to understand how screen time is associated with psychological well-being among children and adolescents to effectively inform clinical practice, policy and research.

As shown in Table 2, several cross-sectional studies examined the role of screen time on childrens and adolescents’ well-being [63, 64, 100,101,102,103,104,105,106,107]. Negative associations between digital technology use and adolescents’ and childrens’ well-being were found in many studies [63, 64, 100, 101, 105,106,107], while a few found no relationship between the use of screen time and well-being [102,103,104]. A high-quality, large study (n = 120,115) in youth from the UK found that moderate digital technology use did not correlate strongly with mental well-being [103]. However, analysis of three large surveys of adolescents in the UK and USA (n = 221,096) [64] revealed that those who use screens for less than 1 h a day reported more favourable psychological well-being than high users (more than 5 h/day). Interestingly, this study indicated that individuals who did not engage in digital media activities at all had poorer well-being than light users [64].

Table 2 Characteristics of studies on psychological well-being
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While results were more consistent among adolescents, studies on young children reported mixed findings. A cross-sectional study in China looked at the relationship between excessive screen time and psychological well-being in 20,324 children aged 3–4 years found a dose–response relationship whereby every additional hour of screen-based pursuits was associated with poorer psychosocial well-being. This association was mostly mediated by the parent–child interaction. According to this study, excessive exposure to screen may have the strongest effect on the frequency of engagement in interactive activities between the parents and the child which in turn can be a risk factor for child psychosocial problems [106•]. On the other hand, null findings were reported in a smaller study examining the associations between moderate levels of TV viewing and psychological well-being among children aged 0–5 years [102]. Similarly, in a large cross-sectional study (n = 19,957), little or no evidence was found to support a link between screen use and psychological well-being among young children [104].

Longitudinal Studies on Screen Time and Psychological Well-Being

Several longitudinal studies (Table 2) have found that higher amounts of recreational screen time predicted lower psychological well-being among children and adolescents [87••, 107,108,109,110,111,112]. A study investigated possible dose–response associations between media use and later psychological well-being among children aged between 2 and 6 years. This study reported that higher levels of electronic media predicted lower psychological well-being, with television viewing being more strongly associated with well-being than e-games and computer use [110]. Another longitudinal study indicated that the high use of social media was associated with poorer well-being, and the relationship was stronger for females than males [87••, 109••]. This gender difference was also apparent in other studies examining the effect of excessive use of video gaming, also called video gaming disorder on psychological and psychosocial well-being. A recent longitudinal study found that video gaming disorder predicted a decrease in psychosocial well-being especially social competencies among boys compared to girls [112]. Similar to those stated above for anxiety and depression, mechanisms underpinning this gender difference might simply reflect differences in use between females and males [87••, 91] which leads to a higher risk of being exposed to cyberbullying [56•, 87••, 113, 114]. Also, the types of games chosen might be associated with gender differences as girls tend to choose puzzle and educational games while boys tend to choose fighting, strategy and action games which might increase their vulnerability to the negative impact of disordered gaming [115]. Another possible mechanism that may explain the association between screen time and mental well-being is sleep, as inadequate sleep is associated with higher use of screen time among children and adolescents [116]; thus, the displacement of sleep, especially among girls, can mediate the association between screen time and mental well-being [56•, 87••]. Furthermore, replacing direct interaction with friends with low-quality, superficial communication of most online interaction online interaction may result in poor social connectedness and lower quality of relationships, which consequently may negatively affect psychological well-being [117].

Taken together, the majority of the reviewed studies, including those using longitudinal designs, indicate a negative association between screen time and psychological well-being, with most of the studies being conducted in adolescents. More inconsistent results emerged from large-scale cross-sectional studies, perhaps due to greater heterogeneity in study measures of well-being, data analyses and sample characteristics [102, 104]. The evidence base among pre-adolescents and young children is moderate, but we highly recommend further longitudinal examination of the relationship between screen time and psychological well-being is needed to gain a better understanding of this association.

Cross-sectional Studies on Screen Time and Body Image

Body dissatisfaction is defined as a negative attitude towards appearance, body weight, size or shape and is one the most robust aspects of the broader concept of body image. Body image concerns are highly prevalent during adolescence when one’s body shape and weight strongly influence one’s self-esteem, and these concerns are especially salient among females [118]. Body image concerns are well known to be detrimental contributors to well-being [119] and significant predictors of psychiatric conditions such as eating disorders and [118] and depression, as well as low self-esteem [120, 121]. With social media platforms such as Facebook, Snapchat and Instagram, body image has become an important target in these activities [122], where individuals post their most flattering photos and view those of others [123], creating an online environment that could be detrimental to body image [124]. Spending time on social media puts adolescents under a higher risk of comparing themselves to more attractive peers [125], and as a result, these unfavourable social comparisons of physical appearance may elicit or exacerbate body image concerns [126, 127]. Screen time, mainly social media use, has received significant attention in research for its potential impact on body dissatisfaction [128]; therefore, it is highly essential to understand how the use of this and other forms of digital media may contribute to adolescents’ body image.

As shown in Table 3, cross-sectional research indicated that screen time [56•, 126, 129,130,131,132,133] especially that spent on social media is associated with body image concerns among adolescents. For example, a large study comprised of high school girls (n = 1087) aged 13–15 years showed that those who use social media frequently reported significantly greater body image concerns such as internalisation of the thin ideal, drive for thinness and body surveillance compared to non-users [131]. Another recent cross-sectional study among adolescents [130] also indicated an association between social media and body dissatisfaction; however, this study found that this association was impacted by the social environment (e.g. relationship with the mother). Specifically, adolescents who reported positive relationships with their mothers had less body dissatisfaction in relation to social media use than those with more negative maternal relationships [130].

Table 3 Characteristics of studies on body image
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Longitudinal Studies on Screen Time and Body Image

Although many cross-sectional [126, 131,132,133] and longitudinal research [136] has focused on females who report high levels of body image concerns, some recent longitudinal studies included both genders [134, 135•]. For example, a study on 604 adolescents aged 11–18 years indicated that both genders experienced the same extent of body dissatisfaction when using social media networking sites frequently [134]. Another longitudinal study involving 1840 adolescents aged between 12 and 19 years showed that passive Facebook usage (consuming information without direct exchanges like posting status or commenting) was associated with more social comparison among adolescent males and females over time [135•]. While social comparison has been clearly implicated in playing an important mechanistic role in the association between screen time and body image concerns, other factors were highlighted in the literature as indicated previously about the buffering effects of positive parent–adolescent relationships [130].

Interestingly, media literacy, which is about being able to think critically about media [137] and being able to assess whether a media content such as an image is realistic or not [138], was suggested as another important protective factor that attenuated the adverse effects on body image among adolescents when exposed to unrealistic thin-ideal media images [139]. Thus, media literacy programs should be examined in more depth using experimental and longitudinal designs as this may represent a promising strategy that protects youth from developing an unhealthy body image known to predict other psychiatric disorders.

Limitations and Strengths

Although this narrative review is representative of key findings from a broad body of literature with the aim to examine the research objectives, there are a few limitations that are noteworthy. This study was not a systematic review of the literature, but rather a narrative review performed by a single reviewer. There may be relevant studies that have been excluded. However, the present review is unique in critically analysing both cross-sectional and longitudinal evidence from very recent studies (past 5 years) about the association between sedentary screen time and mental health, thus providing current evidence to inform future research, practice and policy reform designed to improve children’s and adolescents’ mental health.

Summary, Conclusions and Recommendations

Findings from the present review suggest that screen time is generally associated with depressive symptoms among adolescents, especially females. Evidence on the association between screen time and anxiety among adolescents was mixed and inconclusive and somewhat screen and gender dependent. However, high screen use was consistently shown to be associated with poorer emotional well-being in longitudinal studies, although mixed evidence was found among cross-sectional studies, especially among young children. We also found that high screen time, especially social media use, was consistently associated with greater body image concerns among both male and female adolescents, although females appear more negatively affected. Media literacy and positive relationship with parents appear to attenuate the negative role of screen time on body image, likely by reducing internalisation of unrealistic beauty ideals. Due to the small number of studies in pre-adolescent children, especially preschoolers, it is not possible to determine with any degree of confidence the association between screen time and mental health indicators in this population.

This review highlights that some types of screens are more consistently problematic for mental health than others depending on the content of the media and the characteristics of individuals and their susceptibility levels to the effects of media. For example, social media usage was consistently shown to be associated with depressive and/or anxiety symptoms [36, 56•, 67•, 68,69,70,71,72,73, 82, 86], higher levels of body dissatisfaction [56•, 130,131,132, 134,135,136] and poorer psychological well-being [87••, 109••, 111, 112] among adolescents, with evidence showing that these relationships are sometimes stronger in girls than boys. Regarding mechanisms in which social media may negatively affect mental health, evidence suggests this may occur through a process of unfavourable social comparison, poor sleep and/or cyberbullying [22, 34,35,36, 69, 72]. Although not well studied, the preliminary research among adolescents, especially males, suggests that high use of internet video gaming is associated with more severe anxiety and depressive symptoms. These findings are consistent with a growing body of evidence to suggest that excessive internet-based gaming can produce marked interference in youth’s emotional, familial, social and academic functioning and is being evaluated for inclusion as a behavioural addiction in the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) [140]. Similarly, this review found evidence for associations between excessive computer/internet use and mental health difficulties in adolescents. These findings are consistent with the introduction of new concepts known as “internet addiction disorder” or “internet use disorder”, which are additional types of behavioural addictions characterised by compulsive or pathological internet use that result in marked impairment in functioning. These terms are also being considered for inclusion in the DSM-V [140].

Recommendations for Practice, Policy and Research

Given that childhood and adolescence are critical periods for physical and psychological development, and children and adolescents are spending excessive amounts of time in recreational screen use, the results of this review have significant implications. Based on evidence from this review, we recommend that parents and health practitioners who work with children and adolescents limit recreational screen use to that delineated in the Canadian 24-h movement behaviour guidelines [27]. The findings obtained here also support the new changes in school policy made by the Provincial Ministry of Education in Ontario, Canada, that banned the use of cell phones in schools. Given screen time is associated with an increased risk of obesity [19,20,21] and cardiometabolic disease [21, 22] in children and adolescence, and this review provides robust evidence for detrimental associations with several mental health outcomes, further legislation by other provinces around banning cell phones may follow and these policy changes should be empirically evaluated to see if they have beneficial effects on mental health. There is encouraging evidence that media literacy may be an effective method in which parents, teachers and practitioners can attenuate the harmful effects of digital media use, although more intervention studies are needed. Moreover, developing and maintaining a strong parent–child relationship appears to buffer the negative effects of screen time on several mental health indicators, thus should be targeted in treatment and prevention studies.

Many of the studies used cross-sectional designs, so future longitudinal studies with longer follow-ups and inclusion of potential mediators and moderators including the individuals’ cognitive and emotional statuses that happen during media exposure [40] are needed to gain a better understanding of how various forms of screen use impact children’s and adolescents’ risk of mental health problems over time, and whether effects and mechanisms differ between males and females. In addition, intervention studies designed to determine whether reducing either specific types or duration of screen time or promoting more adaptive use of screens are effective strategies that promote better mental health or prevent mental illness among children and adolescents are needed.