Adolescents estimate that they spend just under 5 hours online every day. This is almost as much time as they spend at school, with the average UK school day lasting 6.5 hours. Adolescent mental health has also declined substantially over the last decade, putting large-scale pressures on UK health services, society and the economy. This has made many concerned that digitalisation is actively damaging adolescent mental health. However, we still know relatively little about whether such concerns are warranted. This is a scientific supply issue highlighted by both the President of the Royal College of Psychiatrists ("We desperately need more research into the benefits and harms of technology use") and the UK Chief Medical Officers ("...more comprehensive research should be supported by health bodies and research institutions. An appropriate mechanism for measuring children's digital engagement needs to be developed..."). A lot of research on digitalisation and adolescent mental health has focused on social media, a particularly high-risk digital innovation. Social media is used heavily by the adolescent population (94% of 16-17s have a social media profile) and introduces changes to the social environment that could amplify pre-existing vulnerabilities. For example, peer rejection is especially salient in adolescence, and a mental health risk factor. Social media quantifies the social feedback adolescents receive from peers through 'like' counts, which could increase the salience of social feedback such as rejection, and therefore increase mental health risk (Mechanism A). Further social media allows for continued access to peers, which is very attractive to adolescents. This can lead to habitual social media use and self-control failures that impact mental health directly and indirectly (Mechanism B). Results of research examining the link between social media use and mental ill health have however been largely inconsistent, and consensus has not moved far beyond statements that the link is complicated. This has made it very challenging to design evidence-based recommendations and interventions to address the impacts of social media across society, policy and industry (e.g., the Online Safety Bill). My fellowship will address this issue by delivering a ground-breaking portfolio of basic and applied research. My team will take a novel mechanistic approach, investigating the mechanisms underlying the impact of social media on adolescent mental health (e.g., Mechanisms A and B, among others). We will first study these mechanisms of interest using observational data across three distinct levels of scientific explanation (experiential, algorithmic, and biological/cognitive). We will then systematically manipulate them in a longitudinal study, to test their mental health impact on an individual level. This will allow us to select two targets that will be developed and deployed in Years 5-7 of the fellowship in both policy and as an intervention that allows adolescents to experiment with changing their own social media use to improve their mental health. This research will be complemented by an agile pipeline of co-investigation and knowledge exchange with policymakers and stakeholders to address current questions in policy and practice, to ensure this investment is continuously creating positive impact for young people throughout the fellowship. This will be supported by an internship scheme that recruits talented undergraduate students from backgrounds underrepresented in academic research to assist my team and policy partners on select summer project 'sprints'. In depth co-creation with young people and parents will further tailor research outputs and dissemination throughout the fellowship. The evidence provided by my fellowship will therefore feed into crucial national decisions about childhood and digitalisation that will shape the lives of our children today and adults tomorrow, for decades to come.

Promoting improved understanding of how children's daily lives are influenced by the digital world that now surrounds them and how they experience family, peer and school life as a result represents a substantial challenge and opportunity relative to facilitating positive mental health and development for children and young people. Historically, researchers have emphasised the role of supportive parenting and positive school experiences (including peer relationships) as primary social environmental influences on children's mental health, with most interventions targeting family and school-based influences aimed at remediating poor mental health outcomes for children and young people. It is increasingly recognised that the digital environment constitutes a new dimension or common denominator to these traditional agencies of socialisation influence on children's mental health. Yet, little progress has been made in equipping parents, teachers and the professional agencies that work with families and schools with new knowledge that harnesses potential strengths while offering protection from substantial risks posed to children by the digital world. How do we equip parents, teachers, practitioners, policy makers and youth themselves with information, support and resources that promotes positive mental health in a contemporary (and future) digital age? Addressing this core challenge represents the primary objective of our multi-disciplinary e-Nurture network. While significant advances have been made in relation to highlighting and understanding the genetic and biological underpinnings of poor mental health and mental health disorders in recent years, it is recognised that the social environments children experience and interact with remain a substantial influence on their positive and negative mental health trajectories (even when genetic factors are considered). Three primary areas of social environmental influence on children's mental health have dominated past research and practice in this area. First, family socialisation processes, specifically parenting practices are recognised as a substantive influence on children's mental health. Second, peer influences are noted as an important influence on children's mental health. Third, school-based factors are recognised as a further influence on children's mental health and development. Increasingly, the digital environment is recognised as a factor that both infuses traditional agencies of socialisation for children and that can influence children directly. Policy makers have recently directed significant attention to the prevalence rates and support needs among children and young people who experience mental health problems. The digital environment and its potential for positive and negative influences on children's well-being, mental health and development has also received substantial research, policy and media attention. Building on this policy platform, the primary objectives of our network are to (1) explore how the digital environment has changed the ways in which children experience and interact with family, school and peer-based influences and what these changes mean for children's mental health, (2) identify how we can recognise and disentangle digital risks from opportunities when working with families, schools and professional agencies in developing intervention programmes to improve mental health outcomes for children and young people, and (3) identify how we effectively incorporate and disseminate this new knowledge to engage present and future practice models and the design and development of digital platforms and interventions aimed at promoting mental health and reducing negative mental health trajectories for young people. The network will engage a collaborative, cross sectoral approach to facilitating impacts by directly engaging academic, charity, industry, policy and front-line beneficiaries (e.g. families, parents, schools, teachers, children and young people).

Promoting improved understanding of how children's daily lives are influenced by the digital world that now surrounds them and how they experience family, peer and school life as a result represents a substantial challenge and opportunity relative to facilitating positive mental health and development for children and young people. Historically, researchers have emphasised the role of supportive parenting and positive school experiences (including peer relationships) as primary social environmental influences on children's mental health, with most interventions targeting family and school-based influences aimed at remediating poor mental health outcomes for children and young people. It is increasingly recognised that the digital environment constitutes a new dimension or common denominator to these traditional agencies of socialisation influence on children's mental health. Yet, little progress has been made in equipping parents, teachers and the professional agencies that work with families and schools with new knowledge that harnesses potential strengths while offering protection from substantial risks posed to children by the digital world. How do we equip parents, teachers, practitioners, policy makers and youth themselves with information, support and resources that promotes positive mental health in a contemporary (and future) digital age? Addressing this core challenge represents the primary objective of our multi-disciplinary e-Nurture network. While significant advances have been made in relation to highlighting and understanding the genetic and biological underpinnings of poor mental health and mental health disorders in recent years, it is recognised that the social environments children experience and interact with remain a substantial influence on their positive and negative mental health trajectories (even when genetic factors are considered). Three primary areas of social environmental influence on children's mental health have dominated past research and practice in this area. First, family socialisation processes, specifically parenting practices are recognised as a substantive influence on children's mental health. Second, peer influences are noted as an important influence on children's mental health. Third, school-based factors are recognised as a further influence on children's mental health and development. Increasingly, the digital environment is recognised as a factor that both infuses traditional agencies of socialisation for children and that can influence children directly. Policy makers have recently directed significant attention to the prevalence rates and support needs among children and young people who experience mental health problems. The digital environment and its potential for positive and negative influences on children's well-being, mental health and development has also received substantial research, policy and media attention. Building on this policy platform, the primary objectives of our network are to (1) explore how the digital environment has changed the ways in which children experience and interact with family, school and peer-based influences and what these changes mean for children's mental health, (2) identify how we can recognise and disentangle digital risks from opportunities when working with families, schools and professional agencies in developing intervention programmes to improve mental health outcomes for children and young people, and (3) identify how we effectively incorporate and disseminate this new knowledge to engage present and future practice models and the design and development of digital platforms and interventions aimed at promoting mental health and reducing negative mental health trajectories for young people. The network will engage a collaborative, cross sectoral approach to facilitating impacts by directly engaging academic, charity, industry, policy and front-line beneficiaries (e.g. families, parents, schools, teachers, children and young people).