On this page, you will find feasibility testing, protocol, frequently asked questions, webinar recordings, and updates from the team on the trial’s development.
Frequently Asked Questions
How long does the intervention run for?
The intervention runs for six weeks.
Why do you think six weeks is enough time to make a difference to young people’s mental health?
We aligned the study with established interventions in this field. Many of the highest-quality relevant studies of behaviour change have run for six weeks longest, and the evidence from these studies supports this as an appropriate length of time. Â
What is the sample size for the trial?
The trial will involve 10 to 12 secondary schools, with an anticipated 4,000 to 5,000 individual participants in academic years 8 to 10.
Does the trial include young people who have no access to mobile phones at all?
Yes. Young people without access to a mobile phone will still be included in the study. They will complete the surveys offline, and this will be recorded appropriately.
Will the app work alongside existing restrictions on participants’ phones, for example, time limits already set by parents?
The app will not override existing restrictions imposed by parents
Will you be monitoring adherence in real time, and will you be able to step in with nudges to encourage adherence?
Nudges are currently limited to prompts that appear when a young person attempts to override the app’s restrictions. They can override the daily limit (2-hours) or the night time curfew. They earn a point each day they don’t override each of these restrictions, for a maximum of two points each day. Each point earns participants 1 ticket into a prize draw conducted at the end of the study. The school with the highest percentage score will also win a cash prize. Â
Will pupils in the control group have the app installed too?
Yes. Participants in the control group will also install the app. There will be no restrictions applied to their use, but the app will record the amount of time spent on linked social media apps. Participants will be blinded to their group allocation; they will only find out which group they are in after completing the baseline survey and installing the app.
What apps are included in the trial?
- TikTok (and TikTok Lite)Â
- SnapchatÂ
- YouTubeÂ
- InstagramÂ
- FacebookÂ
- RedditÂ
- ThreadsÂ
- X (formerly Twitter)Â
- KickÂ
- TwitchÂ
Apple users will not be able to access web versions of these apps through their browser. Android users’ browsers will be included in the list of linked apps.Â
Will you track whether a child is using other apps that are not in scope of the restrictions, for example gaming or messaging apps?
We will ask about this through the surveys completed by young people.
The study measures social media use on a single device. How do you account for the possibility that young people migrate their use to other devices, such as laptops and tablets?
Some degree of displacement to other devices is likely, and we will measure this using surveys.
Will other devices also have the app installed?
No, we will install the app on the participants’ primary smartphones only
Will you track what type of content young people are interacting with when using social media?
No. We are not collecting information on content, as this was a key concern raised by participants regarding confidentiality and data safety. We will not hold identifiable data on what a participant is doing online. We are collecting data on the time and duration of app use to linked apps only, rather than the type of content viewed.v
Will there be an opportunity to identify which types of social media are harmful versus beneficial, so parents can guide use rather than simply limit it?
We will not be able to identify which types of social media are harmful versus beneficial. However, we will be able to describe patterns of screen time on each app.Â
Will you flag young people who are accessing explicit or harmful content, at an aggregate level, or is this outside the scope of the study?
This is outside the scope of the study. We are not examining content in this research.
In the questionnaire, will you be asking about how young people spend their time, to see whether other, potentially non-screen-based, activities replace the time previously spent on social media?
Yes. We will ask questions about other activities as part of the trial.
In terms of mental health-related symptoms, will you assess these daily, or only before and after the intervention?
Before and after the intervention
What change in anxiety do you have the statistical power to detect, and how quickly would you expect changes to occur? Is six weeks a reasonable timeframe?
Assuming we have 12 schools participating, we have enough power to detect effect sizes of ~0.15Â
Circumvention is a known risk in existing online safety measures. Do you have plans to gather data on participants’ circumvention plans or intentions?
Yes. We will explore this through our qualitative work, alongside survey questions.Â
Are you recruiting solely through schools, or are you also looking for other study sites to support recruitment, for example NHS School Nursing services?
We are recruiting through schools.
Are parents given information about, and asked to consent to, their child’s participation in the trial?
Parents are provided with information about the trial and given the opportunity to their child out. Young people who haven’t been opted-out will be invited to participate when the research team visits the school and must then opt-in to join.
How will differences in schools’ existing smartphone restriction policies be accounted for in the cluster randomisation?
The key factors we are balancing across schools are age and ethnicity. Our primary focus is on phone use outside school hours, such as late-night use and use after school, rather than in-school phone use.
How are you going to account for internal validity, given that some apps, such as WhatsApp, are not included in the study?
We have based our initial list of apps on the list used in Australia’s social media restrictions, to align with existing research and contribute to the wider evidence base. As this is a voluntary trial, we also took into account concerns raised by young people that restricting WhatsApp could cause particular difficulties, for example around contacting family and friends.Â
Could you share information on how young people will be incentivised or remunerated for taking part?
Participants will receive a £20 voucher upon completion of the follow-up data collection, and schools will also receive a cash incentive for their participation (£2000). There are also performance-based incentives. Participants in the intervention group can override the daily limit (2-hours) or the nighttime curfew. They earn a point each day they don’t override each of these restrictions, for a maximum of two points each day. Each point earns participants 1 ticket into a prize draw conducted at the end of the study (150 prizes of a £100 voucher). The school with the highest percentage score will also win a cash prize (1prize £5000).
How are you accounting for researcher bias?
We will pre-register all our analyses, meaning we will state how we intend to analyse the data before it is collected. We will also share our data for re-analysis and disclose any potential conflicts of interest, in line with best practice in the public health field.
What is the plan for the qualitative interviews?
We will interview a subset of young people during the intervention, to understand their experience of the restrictions and to help identify possible mechanisms of action, along with any benefits or harms the intervention may produce. We will also carry out follow-up interviews six weeks after the intervention ends, to understand possible longer-term effects.
We’ll be sharing written updates on the trial each month to keep everyone informed.
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