If that sounds positively radical — and also commonsensical — you're right. Mariana Brussoni, a developmental psychologist at the University of British Columbia, has been championing risky play for more than a decade. But the Paediatric Society was never quite ready to endorse her call to action.

It was only when faced with soaring rates of childhood anxiety, depression, obesity and even myopia that the pediatricians came to "realize that letting kids go out and play could be a way to deal with a lot of these challenging issues," Brussoni says.

That's because the doctors came to recognize two truths:

1 — Children are hard-wired to play because it is developmental gold. It teaches them how to take action, get along and solve problems.

2 — Replacing rollicking, kid-led play with structured, adult-led play was a mistake. It deprived children of a million opportunities to exercise their autonomy. And in terms of physical injuries, it turned out to be MORE dangerous.

When kids play without adult intervention it increases their social-emotional skills, says the report. What's more: It can "significantly reduce children's risk for elevated anxiety."

Play does that in a rather obvious way, says Peter Gray, a professor of psychology and neuroscience at Boston College and a co-founder with me of Let Grow. "From an evolutionary standpoint, why do children want to play in a risky way? Because this is how they develop a little courage," Gray says. "They deliberately put themselves into situations where they're feeling fear so that, unconsciously, they can have a sense of control over it: 'I can feel this fear and survive it.' So when they face a real emergency, they are slightly less likely to panic. And they are also less fearful because they know, 'Something can happen and I can manage it.'"