It started with one student, a girl in Year 11, who fainted unexpectedly in a corridor between lessons. Staff at her school, in the North of England, contacted her parents, and she was sent to a GP for them to check there were no underlying issues. All seemed fine.

But the same thing happened again - this time with a different girl, in the same year.

“This kept happening in quite public areas,” says a member of the school’s leadership team, who asked not to be named. “For a while, it happened frequently, at least once a day.”

As more girls began fainting, staff at the school became increasingly worried. There appeared to be no clear explanation for why these incidents were occurring - although some teachers had their own ideas.

“Obviously, schools aren’t health authorities and we couldn’t make any comment on the health of students in that sense, but there were some genuine concerns that there might be a social contagion element to what was happening,” says the school leader.

Social contagion is the spread of ideas, attitudes or patterns of behaviour within a group, through a process of imitation and conformity. In recent years, it has been cited as a reason for upticks in various different mental health and neurodevelopmental conditions - everything from eating disorders and self-harm to tic-like behaviours and attention deficit hyperactivity disorder (ADHD). 

Experts and commentators have pointed to social media - and more time spent online during the pandemic - as a reason why the effects of social contagion are becoming more pronounced.

But just how significant are those effects when it comes to mental health? And what do teachers and school leaders need to know about them?

The effects of social contagion in schools

According to NHS data, the number of children and young people in England needing treatment for serious mental health problems is on the rise. In 2021-22, referrals for treatment for under-18s were up 39 per cent on the previous year. This included children and young people who were suicidal, self-harming, suffering serious depression or anxiety, or had eating disorders.

That increase was likely down to a patchwork of contributing factors, with mental health professionals indicating that national lockdowns, academic pressures and families being squeezed by the cost-of-living crisis were all part of the picture. 

Now, there’s mounting concern about the role that social media might be playing, too. While much of the evidence on the effects of social media on mental health has been mixed, governments around the world are increasingly erring on the side of caution.

In May, the US surgeon general warned that social media use can pose a “profound risk of harm” to children and young people’s mental health. In the same month, the White House announced the formation of a new task force to “advance the health, safety and privacy of minors online”.

In the UK, meanwhile, the Online Safety Bill, which intends to create a new set of laws to protect children and adults online, is currently making its way through the House of Lords. One of the bill’s key aims is preventing children from accessing harmful and age-inappropriate content, including content that “promotes or glorifies suicide, self-harm or eating disorders”, partly in a bid to curb copycat behaviour.

There are concerns in schools, too, about the ways in which increased social media use might be affecting pupils - including how it is leading some to self-diagnose with mental health or neurodevelopmental conditions after viewing content related to those conditions.

“We’ve always had waves of mental health [problems], usually in friendship groups. I guess friendship groups just got massively bigger. [Students] are now friends with people they’ve never met. In fact, some are in relationships with people they’ve never met,” says the headteacher of a secondary school in the Midlands. “Many are seeking solace with like-minded people and it only takes one person to have the germ of an idea.” 

‘I worry that this mental health conversation has ended up disempowering teachers’

Is it possible that young people are “catching” conditions from one another? And from the content they are viewing online?

“There is social transmission, both direct person-to-person transmission and indirectly through different types of media,” says Rasanat Fatima Nawaz, a PhD student in the department of psychiatry at the University of Cambridge, who is studying how we can manage and address self-harm in schools.

“We know that self-harm and suicide can occur in clusters, and it is really important to understand why, because both are preventable,” she says.

Eating disorders can, likewise, appear in clusters, says Tara Porter, a clinical psychologist specialising in eating disorders, who has years of experience working in child and adolescent mental health services (Camhs). 

“It’s something we’ve always noticed. We would have an outbreak of eating disorders in a school but the next year it would be somewhere else. It would move around,” she says. 

Where clusters occur, it’s not as simple as a young person being in the same room as a classmate who self-harms or has an eating disorder and “catching” that behaviour in the way you might catch a virus. It’s also not as straightforward as young people just deciding to copy one another.

We can think of it, Porter says, in terms of smoking. If one young person, who is seen as “cool” or “popular”, starts to smoke, this behaviour can, through a process of influence, spread through the other members of their group. 

Porter believes that something similar might happen with behaviours that trigger, or contribute to, mental health problems. For example, she points out, although “mental ill health isn’t caused by one thing”, “we know that there is a strong link between lack of sleep and mental health problems”. If one young person starts staying up late, that can easily spread through a group of friends, as they stay awake longer to talk to one another.

Spending time with someone who engages in a certain behaviour can also serve to “normalise” that behaviour, adds Porter.

“In terms of my expertise with eating disorders, you can see that a behaviour like missing lunch can become normal. Some girls say to me, ‘Well, none of the girls eat lunch in my school,’” she says.

“And some of these behaviours, they spiral. So you don’t eat lunch, and then it becomes almost competitive or comparative that you don’t eat breakfast, and before you know it, you’re losing weight and you’re into that spiral of an eating disorder mentality.”

It’s easy to see how that spiral might begin when a group of young people are together at school all day. But could something similar happen online?

A thunderstorm in the brain

One recent study seems to suggest so. It details a spate of “tic-like” behaviours in Hanover, Germany. The outbreak was considered to be a case of what’s known as mass sociogenic illness (MSI) - a phenomenon in which people within a social group develop similar symptoms that have no obvious medical cause. In the past, there have been documented MSI outbreaks involving fainting, uncontrollable laughter and leg pain and paralysis.

Kirsten Müller-Vahl, head of a Tourette’s outpatient clinic in Hanover, documented the recent outbreak in a 2022 study entitled Stop that! It’s not Tourette’s but a new type of mass sociogenic illness.

“We see hundreds of patients suffering from tics and Tourette’s syndrome per year. Since 2019 we’ve seen an abruptly increasing number of teenage girls and boys suffering from ‘tic-like’ behaviours we had never seen before,” explains Müller-Vahl.

It was clear that the patients were not experiencing the type of tics traditionally associated with Tourette’s but a type of “functional tic” that was different from those that clinic staff had seen in the past.

When Müller-Vahl and her colleagues began to systematically interview the patients presenting with these behaviours, they found something surprising: all of them had watched a particular YouTube channel before their symptoms started. The channel was called Gewitter im Kopf (which translates as “thunderstorm in the brain”) - and its host presented with exactly the same symptoms as the patients. 

“This was the basis to speculate about [this being] the first documented outbreak of mass social media-induced sociogenic illness,” says Müller-Vahl.

Could a similar outbreak of MSI cause people to present with symptoms of other mental health or neurodevelopmental conditions? It’s certainly possible, says Müller-Vahl.

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However, she warns that not everything can be chalked up to MSI. For instance, she says, “self-diagnosing with ADHD after having watched videos is something different”.

And when it comes to mental health conditions such as depression and anxiety, some researchers think we need to be very cautious about placing the blame on social contagion.

“Social contagion, as the term was originally used, is all about these studies that showed that self-harm, eating disorders, drug use and depression work in physical proximity. So, for example, if you have a happy neighbour, you’re 34 per cent more likely to be a happy person,” says Peter Fonagy, head of the division of psychology and language sciences at University College London and chief executive of the Anna Freud Centre.

According to him, however, all those studies are “flawed” because they don’t control for context. Although there might be “what looks like social contagion”, the spread is more likely associated with other factors. “For example, the fact that if you’re a miserable person, you’re more likely to find friends who are also miserable. It’s selective mating, as it’s called in evolutionary psychology,” Fonagy says.

Another point to consider, he adds, is the fact that the way in which we discuss mental health has changed in recent years; we are now increasingly willing to talk about it and to disclose symptoms, which could be contributing to an apparently higher prevalence of certain conditions. 

That’s not to say that there hasn’t been an overall increase in the numbers of young people who are struggling with their mental health - although it does perhaps mean we should approach figures with caution. 

“So, there is social contagion, but it’s at the level of interpretation,” says Fonagy. “Even more, there’s social contagion at the level of problematising our emotional lives - seeing anxiety and sadness as something that’s a mental health problem, when, actually, it just is what it is.”

The need for ‘mental health literacy’

Lucy Foulkes, Prudence Trust research fellow in the department of experimental psychology at the University of Oxford and author of Losing our minds: what mental illness really is - and what it isn’t, takes a similar view. She believes the language that we use to describe negative feelings is a crucial piece of the puzzle.

“We all feel negative emotions or have negative psychological experiences, but what we name them is very culturally determined and changes across history. We look at how our peers are describing negative feelings, and then we’re influenced to use that language,” she explains.

“I think that’s part of what’s happening on social media. You look at celebrities or your own friends or influencers and the more they start using mental health-type language, the more you’ll be inclined to interpret your own experiences in that way or to interpret them with that language.”

This means, she adds, that young people are now interpreting milder or more transient problems, or “just normal part and parcel of growing up”, as being symptomatic of a disorder.

“I say [this] with an acute awareness that there are plenty of teenagers who are seriously unwell and not being listened to and not getting the help that they really need. But I just think that could be happening in parallel with people overmedicalising in a way that makes the problem worse for everyone,” says Foulkes.

That, arguably, includes making the situation worse for teachers.

Cathleen Halligan is an educational psychologist for a London council. She has observed how social media is driving rising demand for diagnoses, and the subsequent pressure this places on schools.

“I think society is very focused on pathologising children and, although a diagnosis can be very helpful for some people, this also seems to have created a culture of wanting full diagnostic labels to provide reasons for individual differences,” she says. “This seems to be becoming a trend on social media that young people are really picking up on.”

‘With good psychoeducation, we can improve understanding of self-harm without making people feel worse’

Teachers, meanwhile, are expected to pick up the pieces, with schools being asked to do more than ever to support young people’s mental health.

Following the Department for Education’s 2017 Green Paper on young people’s mental health, several new initiatives were introduced, including mental health support teams in schools and training for senior teachers to become mental health leads. Yet there is also, as Foulkes puts it, a “vaguer, bigger cultural shift to expecting schools to be a place where mental health problems are both prevented before they even begin but also treated once they have begun”.

A lot of that responsibility falls on to school staff, who “quite rightly” push back against it, “because they’re not paid mental health professionals”, says Foulkes. 

However, she adds: “I worry that this mental health conversation has actually ended up disempowering teachers in some respects.”

Whereas school staff might previously have intervened “in a helpful way” by just being a “supportive, trusted adult”, there is now an increased belief that they need to refer the problem on to someone else if they see that a student is struggling.

“They could do a lot just by providing social support, but as soon as it is seen through this lens of being a mental health problem, they feel like they can’t touch it,” Foulkes explains.

Fonagy echoes this sentiment: “At the moment, we label everything, we medicalise it. We say, ‘This is a mental health problem.’ And teachers get really scared because they believe this person is going to die by suicide, and that will be down to [them].”

Nawaz says that concerns about social transmission could actually be part of what is driving fears around tackling mental health in schools.

“One of the reasons it’s so difficult to look at self-harm outside of the hospital environment is that we don’t understand the extent to which social transmission occurs. Will it spread if we talk about it? Will it put this idea in young people’s heads?” she says.

Yet in a recent review of school-based interventions to address self-harm, none of the interventions that Nawaz looked at showed iatrogenic effects (in which medical treatment creates a state of ill health or adverse effect).

“They didn’t show students got worse after the intervention. And I think that’s good support to show that, actually, with good psychoeducation, we can improve understanding of self-harm without making people feel worse,” she says.

Fonagy, likewise, believes that schools need to dispel fears about social contagion and focus instead on “mental health literacy” and delivering effective psychoeducation - for both teachers and students.

This doesn’t mean teachers becoming counsellors, he adds. Instead, it involves them not being afraid to do what they would most likely instinctively do: be a calm role model and give sensible advice to children who are struggling, while differentiating between those young people who are having a hard time within the normal parameters of the human experience and those who need specialist care.

“Teachers should be educated in that,” Fonagy says. “They should know what I know about how you can tell the difference between the two, which is basically in terms of loss of function. See if they have a loss of function over several weeks or months. Otherwise, they’re struggling [within the normal parameters of the human experience].”

When it comes to the current challenges that we are seeing around young people’s mental health, the consensus is that social media may, indeed, be part of the problem - but the mechanism by which that happens is certainly not clear cut.

Positive social contagion

So, while it might be helpful for teachers to know about the existence of social contagion, they also need to recognise that talking about mental health isn’t something to be feared. 

“There is an effect there, but it’s small. It’s not like a virus,” says Fonagy. “[And] it’s not as simple as saying that if you are next to somebody who’s miserable, you become miserable.”

In fact, says Uta Frith, emeritus professor of cognitive development at UCL Institute of Cognitive Neuroscience, social contagion doesn’t have to be viewed as a negative phenomenon. It is, she says, part of “normal social behaviour”; it’s a force that drives a sense of emotional belonging, and can fuel shared passions - for a certain type of music, for example.

“It isn’t specific in any way to mental disorders, not at all,” Frith says. “Some of these spreading imitations are bad, it’s clear. But that doesn’t mean that you should stop it, because some will be good. Good behaviour equally spreads like that.

“It’s all to do with our social nature, that’s what I would say. And some of it is very good, and some of it is not very good.”