We can all recall lightbulb moments when some things have fallen into place and become more clearly focused. I unexpectedly had just that sort of experience when I attended my first International Play Association world conference last September in the Canadian city of Calgary.

I’ve been a long-term advocate of the importance of play in children’s development, and it was my intention to spend more of my free time promoting play after leaving office as Scotland’s commissioner for children and young people last year. And so I found myself at this big event - in terms of both scale and ambition - with more than 760 delegates, around half from Canada and the rest from across the world. My lightbulb moment came when I heard Professor Peter Gray, a US psychologist and expert on play, and it concerned mental health. As children’s commissioner, I was frequently asked about the mental health and wellbeing of adolescents in Scotland. We have well-documented concerns about this in schools and beyond, although the decline of adolescent mental health is an international phenomenon in the developed world (“Pupils ‘failed’ by lack of mental health training for teachers”, Tes Scotland, 6 October 2017).

When asked to comment about possible reasons, I used to reference issues around early attachment, the rise of social media, the prevalence of online bullying, increased pressure from exams and a lack of mental health support services. I have no doubt that all of these have an influence. However, I wasn’t entirely satisfied that these explanations hit the mark entirely.

It was only when Professor Gray traced the decline in play opportunities over the past four decades, and the rise in adolescent mental health problems, that it dawned on me that this was more than just an association. He linked the contraction in roaming space for children in communities with the sanitising of risky elements of play, and postulated that these experiences are necessary for the development of children.

I was reminded that through play, children learn how to make decisions, solve problems, exert self-control and follow rules. They learn to regulate their emotions and how to make friends and get along with others as equals. And all of this builds inner resilience, which is necessary to face the trials of later childhood. If these learning opportunities are missing, children are missing out on a fundamental aspect of their development.

I could see more clearly that the lack of play was a common issue for children in the modern world, and that we needed to respond to that trend (“Calm, not chaos, rules at school where play is king”, Tes Scotland, 26 January).

We do not have random controlled trials to demonstrate that play-deprived children are growing into adolescents with poor mental health, but we do have a growing number of academics producing work probing and shedding light on the links between mental health and play opportunities for children.

I believe that poor mental health in adolescents is directly linked to the lack of play opportunities in childhood, which is leading to a lack of inner resilience to cope with the stresses and strains of adolescence.

While I had previously expressed concern about the lack of play opportunities for children, I had not previously made the connection with mental health problems in adolescence. Or rather, when I was asked about the mental health problems of adolescents, I did not link it back to lack of play earlier in their childhood.

I now have made this link, and have spoken about this to audiences who easily get it - this just makes sense to them. I have noticed roomfuls of nodding heads when I have made this argument, and the conversations afterwards have confirmed my belief that this is a major issue that, though commonly understood, needs a far greater airing before things really get better. Sustained action is needed to create the space for children to experience the kind of play opportunities they require.

I know that for some of the more seasoned delegates at the Calgary conference, the content was not quite as seismic - that they may have had heard it all before. But it is so important to get this message into the wider public domain, to try to prompt action right now. These messages surface occasionally in the media and, as a result, there is some hand-wringing about the squeezing out of play from modern life. But this just isn’t sufficient.

Our adolescents are in crisis because of our misplaced protection in childhood, leaving them ill-equipped to cope in their later years when faced with challenges in school and other settings. This issue is not going to go away. Real action must happen - and soon.

I was also in Calgary to take part in hustings for elections to the International Play Association board, and I was privileged to be elected as a member for the next three years.

My intention is to use this role to work tirelessly so that messages around the fundamental importance of play to children’s mental development percolate into mainstream thinking much more potently than they do at present. I want to press for tangible action to reverse the current worrying trends around play - there is an awful lot of work to be done.

Tam Baillie was Scotland’s commissioner for children and young people from 2009 to 2017