There has never been a time when schools have been more focused on pupils’ wellbeing.

Inboxes are bulging with resources to download, there’s a new Wellbeing Charter you can sign up to and the government’s pledge to train a senior mental lead in every school by 2025 is taking shape.

It is a good moment, then, to look at the evidence on what works in promoting wellbeing and tackling mental health problems - and what does not.

That’s what a new report from the Early Intervention Foundation (EIF) has set out to do with, arguably, the most comprehensive review yet of the evidence on school-based mental health interventions.

The review is based on a substantial body of evidence - 34 systematic reviews published since 2010 and 97 one-off intervention studies published in the past three years - and from this, the EIF has found some widely used approaches may, in fact, be based on myths or partial myths that schools need to be aware of.

Myth number 1: raising awareness and reducing stigma about mental health means pupils will seek help if they need it

Most schools are using assemblies, lessons and digital resources to increase pupils’ awareness of the importance of good mental health, the signs and symptoms of mental health difficulties and sources of support.

The EIF review, however, found that while interventions like these consistently improved students’ knowledge, their comfort in talking about mental health and their ability to recognise signs of mental health difficulties, there was little evidence that they impacted on attitudes to mental health or whether pupils sought help.

Knowledge does not necessarily change behaviour. I am reminded here of a recent finding from a survey of over 3,000 secondary students, in which almost half of pupils said they wouldn’t speak to anyone in school if they were worried about their mental health or that of another pupil.

Clearly, then, for schools it cannot be the case that simply talking about mental health is enough. It will be important to explore the quality and strength of relationships that pupils have with school staff, and ask students for their advice on what might encourage them to let others know if they are feeling stressed or unhappy.

Myth number 2: PSHE can be relied on to promote increased pupil wellbeing

This may, according to the evidence, be a partial myth. Personal, social health and economic education can be effective in promoting wellbeing but it depends on the particular approach.

Again, knowledge is not sufficient. Instead, the review finds strong evidence for approaches that systematically develop the social and emotional skills that underpin wellbeing.

A number of well-evidenced social and emotional learning (SEL) programmes available in this country are listed in the EIF Guidebook. SEL programmes work, according to the review, when they follow the SAFE (sequential, active, focused and explicit) principles described in the EIF and Education Endowment Foundation’s SEL guidance for primary schools (sequenced set activities which develop skills chronologically, active forms of learning, focused time to develop skills and explicit targeting of a core set of skills).

The EIF research suggests another potential pitfall in relying on PSHE alone. There is, it finds, no point in importing standalone programmes, however well evidenced, into a school that lacks a supportive whole-school environment.

This is brought home in a recent report, which found that almost half of pupils surveyed had been disciplined by their schools for behaviour linked to mental health problems.

The implication here is that effective implementation of mental health interventions in real-world practice requires substantial investment in high-quality training, monitoring and support - for all staff, not just a few.

Myth number 3: school staff can provide mental health interventions with support from external professionals

At a time when more and more seems to be asked of schools, the review invites us to reflect on what can be asked of school staff and what should be the province of others.

The evidence is clear: universal interventions to promote mental health and wellbeing can be effectively delivered by teachers. There is very good evidence that, through well-taught SEL classroom programmes, pupils can learn to better understand and manage their emotions, communicate their needs and build strong relationships with others.

There is, however, no evidence that targeted interventions delivered by school staff are effective in addressing the needs of students with clinical symptoms of depression and/or anxiety.

The review finds that for this group of young people, CBT interventions delivered by external professionals provide the only convincing evidence of improving mental health outcomes.

Mental health support cannot be done on the cheap. It may be that the promised local mental health support teams will, in the long run, provide the specialist services that pupils need, as long as some of their work is undertaken directly with students.

But, meanwhile, as exhausted school staff look to the school holidays to restore their own wellbeing, we need to be clear about what should and what should not be asked of them in the future.

Jean Gross CBE is an EIF associate. She co-authored the EIF and Education Endowment Foundation’s guidance report, Improving Social and Emotional Learning in Primary Schools