Sedentary Behaviour and Mental Health in Children and Adolescents: A Meta-analysis

Department of Psychology, Methodist University College Ghana, P.O. Box DC 940, Dansoman-Accra, Ghana

*Corresponding Author:

Mavis Asare
Department of Psychology, Methodist University College Ghana
P.O. Box DC 940, Dansoman-Accra, Ghana
Tel: +233 272 06 31 93
E-mail: masare@mucg.edu.gh

Received Date: October 27, 2015 Accepted Date: November 12, 2015 Published Date: November 16, 2015

Citation: Asare M (2015) Sedentary Behaviour and Mental Health in Children and Adolescents: A Meta-analysis. J Child Adolesc Behav 3:259. doi:10.4172/2375-4494.1000259

Copyright: © 2015 Asare, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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Abstract

Background: A growing body of research is emerging examining the associations between sedentary behaviour and mental health in young people. The magnitude of the impact sedentary behaviour has on the mental health of young people has not been examined, though this has been investigated for physical health conditions. The aim of this article is to examine the associations between sedentary behaviour and mental health in young people aged 5-18 years of age using meta-analysis. Methods: Published studies in the English language were located via manual and computerised searches of PubMed, Science Direct, SPORTDiscus, PsychINFO, Medline, Web of Science, Cochrane Library, and Google Scholar databases. Included were observational studies assessing an association between at least one sedentary behaviour and at least one aspect of mental health in young people aged 5-18 years. Effect sizes (ESs) were calculated for each study and an overall effect size was computed. Average effect sizes were also calculated for moderator variables. Results: Thirty-five studies were included (n=373,512); most studies examined screen-time as sedentary behaviour and five mental health outcomes were identified (depression, anxiety, self-esteem, psychological distress, and quality of life). The summary effect was small and significant (ES = -0.30, 95% confidence intervals = -0.20, -0.45, p<0.001), suggesting that sedentary behaviour is negatively associated with mental health in young people. Moderator analysis showed that television viewing had the largest effect size (ES = -0.47, 95% confidence intervals = -0.35, -0.62, p<0.001). Moreover, depression seems to be the main mental health outcome affected by sedentary behaviour (ES = 0.55, 95% confidence intervals = 0.42, 0.68, p<0.001). Conclusions: There was a small but a significant negative association between sedentary behaviour and mental health. High levels of sedentary behaviour are associated with increased depressive symptoms. This finding is consistent with a systematic review on adults which indicated that sedentary behaviour is significantly associated with mental health problems.

Keywords

Sedentary behavior; Sitting time; Screen; TV; Video game; Computers games; Mental health; Depression; Anxiety; Stress; Psychological distress

Background

Mental health is a complex part of cognitive neuroscience influenced by different factors such as biopsychosocial –i.e. biological, psychological, social and environmental systems [1]. Individual lifestyles have become a central focus in healthcare since population patterns of ill health have changed from contagious to lifestyle diseases [1,2]. It is well established that physical activity is associated with positive health in all populations. The health benefits of physical activity have led to the development of physical activity guidelines for adults and young people [3]. Research has shown that many young people are not meeting the physical activity guidelines [3-5]. In addition, more recent research suggests that many young people spend large proportions of the day in sedentary pursuits. Sedentary behaviour has been defined as any waking behaviour in which energy expenditure is ≤1.5 METs while in a sitting or reclining position, and includes behaviours such as watching television, travelling by car/ public transport, sitting in class, playing computer games etc. [6]. Sedentary behaviours have increased among young people partly due to the technological development of attractive home-based entertainment devices, homework and leisure use of computers, and high levels of sitting at school, with or without computer screens [4]. Therefore, during leisure time a number of adolescents, especially boys, sit to play video and computer games. Girls also use the computers for diverse reasons, including social contact and shopping [7,8]. Television is the most common entertainment device which is available in most homes and is widely used by young people [9]. However, the computer/internet is the most valued media among young people because of the wide variety of its use including e-mail, social networking, playing games, watching movies, and searching information [10]. In modern society, the use of screen-entertainment devices are often thought to replace active games among adolescents [4], although precise data are lacking.

Recent research has shown that high levels of sedentary behaviour in young people can have a negative impact on their health. High levels of sedentary behaviour have contributed to the increase in chronic diseases such as obesity, type 2 diabetes and heart problems among adolescents [11-14]. Young people are therefore predisposed to health problems through multiple unhealthy lifestyles including physical inactivity (low levels of physical activity) and sedentary behaviour (high levels of sitting).

An aspect of health which has received considerable attention by researchers and public health professionals is mental well-being [2,15,16]. Mental health difficulties have become common among young people, especially adolescents. It has been estimated that every year about 20% of adolescents suffer mental health problems including depression, anxiety, low self-esteem and major mental illness. The most common of these problems among adolescents is depression [16]. The rise in mental health problems among young people could dramatically increase health care costs [3]. Moreover, mental health problems may affect school attendance and create learning problems for young people [17].

Due to the increasing prevalence of mental health problems in young people, researchers have been investigating possible contributing factors. There is a need for preventing and controlling mental health problems. While physical activity and mental well-being has been studied extensively in adults, but less in young people [18], there is currently no synthesis of evidence aggregating findings on sedentary behaviour and mental health in young people. Therefore it is timely to review the evidence. The aim of this paper, therefore, is to examine the association between sedentary behaviour and mental health in young people using meta-analysis.

Methods

Literature search

Papers were searched using key terms indicating: 1) sedentary behaviour (e.g., sedentary, television, video, DVDs, computers, screentime and sitting); 2) mental well-being outcomes (e.g., mental health, psychological well-being, health related quality of life, quality of life, depression, stress, anxiety and self-esteem); and 3) youth population (e.g., children, adolescents, teenagers and young people). PubMed, Science Direct, SPORTDiscus, PsychINFO, Medline, Web of Science, Cochrane Library and Google Scholar databases were searched using the specified key terms.

Inclusion and exclusion criteria

To be eligible for inclusion the study must: 1) include children and/or adolescents aged 5-18 years; 2) have a quantified measure of sedentary behaviour (studies that measured the content rather than quantity of time consuming screen-based sedentary behaviour, such as aggressive movies, horror films, etc., were excluded); 3) have a measured mental health outcome as specified in the key terms list; 4) provide a quantified association between at least one sedentary behaviour and one mental health outcome; 5) be published in a peerreviewed journal in the English language up to June 2012.

Data extraction and coding

Information from the studies included were extracted onto standardised forms developed for this review. Information extracted from each of the studies included: authors of the paper, country of study, type of study, type of population, sample size, age range of the sample, response rate, type of sedentary behaviour assessed, mental health outcome assessed, and validity and reliability of measures used to assess sedentary behaviour and mental health. Some authors of the papers were contacted for clarification of some information when necessary.

Quality assessment of the papers included

The quality of all the studies were evaluated mainly based on their methodological strengths using a checklist [19,20]. The criteria evaluated included the sampling procedure, inclusion of adequate sample size, tools for assessing the constructs being investigated, and statistical analyses. Similar criteria were used to evaluate both crosssectional and longitudinal studies, but longitudinal studies were evaluated with additional two items. Specifically, the criteria for evaluating longitudinal studies included additional items that evaluated adequate response rate at follow up and appropriate description of follow up duration or assessment. Thus, the total score for the quality grading was 11 points for cross-sectional studies and 13 points for longitudinal studies. In this meta-analysis, studies that obtained scores equal to or above the mean score were classified as high quality whereas studies with scores below the mean score were classified as low quality studies.

Data coding

Studies included in the meta-analysis were coded on a number of characteristics, based on hypothesised moderators. Specific information on coded variables was based on study design and coded as cross-sectional or longitudinal. Age group of the participants were coded as children (ages 5 to 11 years), adolescents (ages 12 to 18 years), or a combined sample of children and adolescents (ages 5 to 18 years). Gender was coded as boys only, girls only; and boys and girls. Studies were coded for the type of screen assessed in order to compare the impact of particular screen use on mental well-being. Coding included television, computers, video/DVDs, screen, and sedentary behaviour. Indicators of mental well-being were coded as anxiety, depression, selfesteem, psychological distress, and quality of life. Irrespective of the research designs of the studies included, the quality of the methods and style of reporting findings were evaluated. Thus, studies were coded as high quality or low quality based on the criteria described above.

Statistical analyses

The Comprehensive Meta-Analysis (CMA) version-2 software was used to calculate effect sizes for the relationship between sedentary behaviour and mental well-being. The effect sizes for the individual studies were computed. An overall effect size was calculated for all the studies. The effect size was expressed as Hedges’ g. The effect of heterogeneity was estimated using the Q measure. Where the test of heterogeneity was significant, it meant that there was a need to examine moderator variables. Some moderator variables hypothesized before the meta-analysis included: i) the research design, ii) age group of participants, iii) type of sedentary behaviour, iv) mental health outcome and v) study quality. The magnitude of the effect sizes were assessed using Cohen’s [21] criteria: small = 0.2-0.49; moderate = 0.5-0.79; and large = ≥0.08.

Results

Identification of relevant studies

Potentially relevant articles were selected by (1) screening the titles; (2) screening the abstracts; and (3) if abstracts were not available or did not provide sufficient data, the entire article was retrieved and screened to determine whether it met the inclusion criteria. A customised ‘in-out’ form was used to appraise the studies for inclusion or exclusion. This led to 69 papers being excluded and 35 papers included for the meta-analysis. The screening process followed the PRISMA guidelines [22]. The screening procedure is shown in Figure 1.

Figure 1: Meta-analysis screening process.

Study characteristics

The studies included were mainly conducted in the U.K, U.S., Canada, Germany and China. Almost all the studies examined screenbased sedentary behaviour. Only about two studies [23] assessed total sedentary behaviour. The majority of the studies used the Centres for Epidemiologic Studies Depression scale to measure depression [24-26]. Only some few studies used a clinical diagnostic tool such as the Beck Depression Inventory to measure depression. A number of the studies used the Strengths and Difficulties Questionnaire to measure mental health [27,28]. Moreover, most of the studies used the physical selfperception scale to assess self-esteem.

Participant characteristics

Studies included 373,512 young people. Participants were boys and girls aged 5 to 18 years who were attending schools. The majority of the studies included both children and adolescents. Some of the studies included only children. However, very few studies focused solely on adolescents.

Quality assessment

Generally the quality of the studies included was quite poor. This was mainly because a significant number of the studies did not use validated tools to measure sedentary behaviour and mental health. Some of the studies also measured mental well-being by proxy reports which may not accurately represent the children’s mental well-being. Three studies were rated the highest score of 8 out of 11 points. A significant number of studies obtained lower scores ranging from 5 to 3 points (Table 2).

Meta-analysis

Overall effect size: The mean overall effect size for the association between sedentary behaviour and mental well-being was small but significant (ES = -0.30, 95% confidence intervals = -0.20, -0.45, p<0.001; K=37; n=373,512) (Cohen, 1988). The test of heterogeneity was also significant [Q (36) = 20706.43, p<.001], therefore potential moderators of the association between sedentary behaviour and mental well-being were examined. The Q values, significant levels and the effect sizes of the moderator variables are presented in Table 1.

Table 1: Homogeneity tests and effect sizes for moderator variables.

Effect Sizes for Moderator Variables

Design

Both types of research design had significant effect sizes. Crosssectional studies had a larger effect size than longitudinal studies, although the latter had only 4 studies (Table 1).

Subject characteristics

Most of the studies that have investigated sedentary behaviour and mental well-being have not reported effects separately for children and adolescents. Therefore, we could only provide effect sizes for children and adolescents combined.

Type of sedentary behaviour

All types of sedentary behaviour were significantly associated with mental well-being except total sedentary behaviour (ES = -0.05, 95% confidence intervals = -0.03, 0.10, p>0.05). The largest effects were seen for general screen use (ES = -0.51, 95% confidence intervals = -0.34, -0.65, p<0.001) and television viewing (ES = -0.47, 95% confidence intervals = -0.35, -0.62, p<0.001).

Measures of mental well-being

The largest effects were seen for depression (ES = 0.55, 95% confidence intervals = 0.42, 0.68, p<0.001) and psychological distress (ES = 0.41, 95% confidence intervals = 0.30, 0.56, p<0.001). The smallest effects were identified for anxiety and quality of life. However, there was no significant effect for self-esteem.

Study quality

Only the high quality studies had significant effects (ES = -0.31, 95% confidence intervals = -0.20, -0.45, p<0.001).

Discussion

This meta-analysis is the first to evaluate the association between sedentary behaviour and mental well-being in young people. Studies indicate a small but significant negative association between sedentary behaviour and mental health when assessing mainly screen-based sedentary behaviour and various indicators of mental health. Our findings are consistent with a systematic review with adults showing that sedentary behaviour is associated with higher levels of depression in adults [29]. The present findings are also consistent with those finding that sedentary behaviour influences physical well-being independent of physical activity levels [30,31].

All types of screen use, except video/DVD use, were significantly associated with poorer mental health among young people. Among the kinds of screen assessed, television use had the largest association with mental health compared to computers and video games. Research findings indicate that the main period in which young people are sedentary is after-school hours when they have returned home [32]. With television being the most common entertainment device at home [33], young people are more likely to use television for leisure activity than other kinds of screen. For example, it has been indicated that about 60% of young people have television in their bedrooms [34], which suggests that these young people are more likely to watch television after school hours.

Particularly, television use had a larger association with mental health problems than computers. The possible explanation for this finding is that TV viewing involves less stimulation of the brain, compared to computer use therefore making it more associated with mental health problems. Using computers, however, may involve much more mental stimulation due to activities such as typing on the keyboard, using the mouse, clicking buttons, etc. which may distract the user from worrying and therefore reduce mental health problems.

It should also be noted that when not accounting for television, the highest effect size occurred for combined screen use. There is the possibility that the larger effect size for combined screen use was associated with television use than other kinds of screen. However, total sedentary behaviour was not significantly associated with mental health. This finding was not surprising because few studies have assessed overall sedentary behaviour and only 2 studies were assessed here. Moreover, since total sedentary time was associated with poor mental well-being but not significant, it also suggests that perhaps screen use constitutes the main aspect of sedentary behaviour in young people than other aspects of sedentary behaviour associated with reading, sitting to chat without screen and travelling. Strasburger [10] mentioned that young people spend a greater proportion of their leisure time using screen devices than any other activity.

Regarding the indicators of mental well-being, depression has the largest effect compared to the other measures of mental well-being. Furthermore, sedentary behaviour was not associated with self-esteem. This finding contradicts studies which have shown that depression is highly associated with self-esteem [35]. Based on the evidence that individuals who are depressed are more likely to experience self-esteem problems, it was expected that sedentary behaviour would be associated with self-esteem as well. However the current finding is supported by studies which have showed that the use of some screens is associated with improved self-esteem among young people [36].

Specifically some studies have found that the use of computer is associated with improvement in social self-esteem [8,37]. Moreover, in the present findings computer use had a smaller impact on depression. Therefore it could be that young people who used computers experienced some improvement in some aspects of their self-esteem [37] which resulted to a reduction of the possible impact that computer use might have on depression. This is because improvement in selfesteem significantly reduces depression [35,38]. It should however be noted that the use of computers have been associated with social selfesteem, but not other domains of self-esteem [37].

Concerning the age group of the young people examined, the lack of studies assessing children and adolescents separately did not allow for a comparison of the impact of sedentary behaviour on these two age groups. Given that findings indicate that adolescents are more likely to be sedentary than children [39] and adolescents are more prone to depression than children [40], it is important to determine the extent to which sedentary behaviour separately might differentially affect both children and adolescents.

Among the studies that have assessed sedentary behaviour and mental well-being, nearly half (46%) were of low quality. Interestingly, the high quality studies showed larger effects than the low quality studies. It is important to note that the significant number of low quality studies that have assessed sedentary behaviour and mental well-being in young people might be the reason why a small effect was determined for the overall association between sedentary behaviour and mental well-being. Specifically, a number of the studies did not use standardised tests to measure mental well-being [41,42].

Limitations of the Findings

The findings reported in this meta-analysis have some limitations. Specifically, the data are based on rather few studies, the majority of which have methodological limitations, including being mainly crosssectional where reverse causality cannot be ruled out. For example, there is evidence that people who are depressed may participate less in physical activities [38,43]. Participating in less physical activity may increase the likelihood of being sedentary [44]. Moreover, having poor mental health may predispose one to sit more. In addition, studies that were examined assessed mainly screen use, therefore the findings does not show the impact of the entire range of sedentary behaviours on young people’s mental well-being. Young people also engage in multiple sedentary behaviours in different settings [44].

Implications of the Findings

This meta-analysis supports the sedentary behaviour guidelines [3]. The government and the public health agencies need to take account of physical activity and sedentary behaviours in their agenda when promoting health among young people. School physical education, which is an important subject that would expose students to physical activity and reduction in sedentary behaviours should be well structured. Introducing structured physical activities into mental health care is likely to reduce sedentary behaviour [44] and facilitate recovery [45-50].

Conclusion

Few studies have investigated sedentary behaviour and mental wellbeing in young people. There is a need for additional studies, especially among adolescents. Studies which investigate sedentary behaviour among young people should provide separate results for children and adolescents [51-65]. Moreover, studies investigating sedentary behaviour need to assess a greater variety of sedentary behaviour contexts in order to determine the association between different sedentary behaviours and mental well-being. There is a need for longitudinal, prospective and experimental designs to further examine the impact of sedentary behaviour on mental well-being. This area of research has not been investigated with experimental studies and it is only these that will resolve the issue of whether reverse causality is at play [65-71]. In summary, a small but significant negative effect has been shown between sedentary behaviour and mental well-being. Sedentary behaviour is most clearly associated with depression among young people. This finding is in line with reports stating that depression is the most common mental well-being problems experienced by young people [16].

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