What Screen Time Really Does to Young Minds and Why We Need Better Evidence

Summer holidays mean longer days, plenty of sunshine, and, let’s be honest, children glued to their screens. The constant tug‑of‑war between TikTok and the trampoline is an all too familiar scene. Before resorting to another round of "Put your phone away!" I wanted to explore what the science actually says. The UK government has recently commissioned a major research project led by the University of Cambridge to sift through existing evidence and work out exactly how smartphones and social media are affecting young people’s mental and physical health, and whether the methods we use can actually prove cause and effect. You can find more information about this here. That’s big news, and it’s a sign that policymakers are recognising both the risks and the opportunities of the online world.

Why now? Turns out the evidence isn’t as solid as we think

Parents, teachers and therapists have been worrying about screen time for years, yet the science is far from settled. Many studies rely on children reporting how long they spent online and how they felt, which isn’t always accurate. The UK’s Chief Medical Officer concluded in 2019 that there wasn’t enough high‑quality evidence to underpin national guidance. This has left families without clear, consistent advice. Even today, the Royal College of Paediatrics and Child Health and the American Academy of Paediatrics do not issue specific time limits.

Some research paints a reassuring picture. A large study combining more than 11,500 brain scans of children aged nine to twelve found no evidence that spending hours on screens was linked to poor mental wellbeing or cognitive problems Another review of eleven studies found no overall evidence that light from screens before bedtime made it harder to sleep. You can find more details on this research in this BBC article.. Put simply, the doom‑laden headlines often overstate the case. 

That doesn’t mean there are no risks. Specific online harms, such as exposure to explicit content, grooming or cyberbullying, are of course very real. And when screen time crowds out sleep, in‑person friendships and physical activity, that combination can be a terrible formula for mental health. The problem is separating correlation (two things happening together) from causation (one thing causing the other). 

What the new study will do

The Cambridge‑led project brings together researchers from universities across the UK. Their first job is to work out which research methods and data sources can identify causal relationships between smartphone use, social media and the health and development of children and young people. A simple association isn’t enough, as policymakers need to know whether tech use causes harm or benefit, not just whether the two are linked.

To answer that, the team will review and summarise existing studies on how smartphones and social media affect mental health, physical health, lifestyle, health behaviours and educational attainment. They’ll assess which approaches (for example, randomised experiments, longitudinal studies, brain imaging, data from tech companies, and so on) can provide robust evidence. Crucially, the review will consider the diversity of young people’s experiences and the fact that online habits and emerging technologies change rapidly.

This foundation will allow the researchers to recommend how new studies over the next two to three years could deliver strong causal evidence. Technology Secretary Peter Kyle has been clear that the aim is to build a trusted evidence base so the government can protect and empower young people as the digital world evolves. Dr Amy Orben, who leads the project, notes that the issue is complex and changing quickly, so research methods need to innovate just as fast. You can read her statement in full here, she also emphasises that evidence creation must keep pace with technology to ensure decisions are “informed, timely and evidence‑based”.

Lessons for families today

Waiting for new research doesn’t mean we’re powerless. Most experts agree it’s not just the amount of screen time that matters, but what children are doing online and how it fits into their broader lives. While we can’t point to one magic number of safe hours, we can encourage healthier habits and help young people develop digital resilience.

Here are some practical, evidence‑informed strategies:

• Set realistic boundaries. Agree as a family when devices go away, for example, at meal times and an hour before bed. It's really important to then stick to it though. This means that adults have to follow the rules too, as children and teens are expert hypocrisy detectors.

• Make bedrooms screen‑free. Charging phones outside the bedroom removes the temptation for midnight doomscrolling and encourages better sleep. An old‑fashioned alarm clock can feel oddly luxurious.

• Model healthy habits. Children learn by watching. If you scroll through your phone while watching a film, expect them to do the same. Try leaving your device in another room during family time.

• Co‑view and discuss. Watch YouTube videos or play games together. Ask open questions, such as: “What do you enjoy about this?” or: “How do you feel after spending time online?”  in order to help them develop critical thinking.

• Choose age‑appropriate platforms. Privacy settings and parental controls change constantly. Don’t be afraid to say “not yet” if a platform doesn’t feel right. Help children understand why some apps have age restrictions.

• Encourage offline activities. Sports, music, art, reading, baking, whatever sparks joy and competes with screens. You could make it playful by instituting a family “digital detox” hour where the first person to reach for their phone does the washing up.

These ideas emphasise balance. Tech kept many of us sane during lockdowns, and for some young people, especially those with niche interests or marginalised identities, online communities can be a lifeline. Yet endless scrolling at 2 am rarely makes anyone happier. The quality of what children do online and the context in which they do it matters far more than counting minutes.