'There's more to life than staring at a small screen': a mixed methods cohort study of problematic smartphone use and the relationship to anxiety, depression and sleep in students aged 13-16 years old in the UK.

Background: Depression and anxiety are common in adolescents and have increased over the last decade. During that period, smartphone usage has become ubiquitous.

Objectives: The study aim was to assess the association between problematic smartphone usage (PSU) and anxiety.

Methods: Using a prospective mixed methods cohort study design, students aged 13-16 year old from two schools were enrolled regarding their smartphone use, mood and sleep via a semistructured questionnaire at baseline and week 4. The primary outcome was symptoms of anxiety (Generalised Anxiety Disorder Questionnaire, GAD-7) and exposure was PSU (Smartphone Addiction Scale Short Version). A linear regression was fitted to assess the change in anxiety. Thematic analysis of free-text responses was conducted.

Findings: The sample included 69 participants that were enrolled and followed up between 28 March and 3 June 2022. Of those with PSU, 44.4% exhibited symptoms of moderate to severe anxiety compared with 26.4% of those without PSU. There was a linear association between change in symptoms of anxiety and PSU β=0.18 (95% CI 0.04 to 0.32, p=0.013). Several themes were found: both positive and negative effects of smartphones on relationships; negative effects on school performance and productivity; mixed effects on mood; a desire to reduce the amount of time spent on smartphones.

Conclusions: Increased anxiety, depression and inability to sleep were seen in participants as their PSU score increased over time. Participants reported both positive and negative effects of smartphones and almost all used strategies to reduce use.

Clinical implications: Interventions need to be developed and evaluated for those seeking support.