Hundreds of thousands of Australian children and teenagers are experiencing serious mental health issues, but many parents have no idea what is going on, according to a groundbreaking national survey.
Experts say the research is a wake-up call for parents and doctors to help them recognise when  children are unwell, and an indicator of the huge need for more services to help young people deal with anxiety and depression.
As many as one in 10  children, some as young as four, have mental health disorders according to the survey, released on Friday, which also found widespread self-harm as well as anxiety and depression. 
It's estimated about 560,000 children experienced a mental health disorder in the past year, with 1 in 13 children aged between 12 and 17 seriously considering suicide. One in 20 had already picked a place to do it.
The survey is the biggest  into child and teenage mental health in Australia, and the first to examine the prevalence of anxiety disorders, with nearly 7 per cent of children suffering from them.
The chief investigator on the research project, Associate Professor David Lawrence, said the data showed there was a high level of distress among young people.
"There is a group of teenagers who are telling us they are going through a period of significant distress, and their parents aren't aware of the full extent of it in all cases," he said.
The research was unique in that the team, from the Telethon Kids Institute at the University of Western Australia, talked to more than 6300 families but also gave the children the opportunity to fill in a separate, secret survey.
While only 4.7 per cent of parents provided information that indicated their children had a major depressive disorder,  the rate from the separate children's survey was 7.7 per cent.
Major depression was more common among the older teenagers, while anxiety disorders were seen across all age groups.
Associate Professor Lawrence said the nature of the conditions identified in the children had also changed since a similar survey in 1998. Fewer children today had ADHD, but more had depression.
While the research could not identify why, he suggested  that changed environments for children could have contributed, with more pressure for academic achievement and competition for university places and jobs, as well as cyber-bullying, adding new pressures.
"I doubt that when these new technologies were rolled out that a lot of planning and thought was given to  how they were going to impact children and young people's wellbeing," he said.
Health Minister Sussan Ley said there was no doubt many of the findings were confronting, but there were also many positive signs.
"It's heartbreaking to see these prevalent stories of depression, anxiety, self-harm and suicidal tendencies amongst our young people," she said.
"But it's also a credit to young Australians, and society as a whole, that so many are now not only bravely opening up about their emotions and behaviours, they're actively seeking out help and taking positive actions to manage them."
While fewer than a third of kids had accessed mental health services in the 1998 survey, more than two thirds had today. And those with the most severe disorders were more likely to have accessed help.
"In years gone by many of these cases we're hearing about today would have simply gone unaccounted for while people suffered in silence."
She said the survey had made her all the more determined to ensure that mental health reform was done right.
The chief executive of youth mental health group Headspace, Chris Tanti???, said the sheer size of the problem meant more services were needed.
"We are talking about five or six hundred thousand children, and we are currently seeing 60,000 and when we scale up it will be 120,000, so we are just scratching the surface of this thing," he said.
In particular, help for children aged under 12 was lacking - along with training and support for parents in both recognising mental illness and knowing where to seek help.
Mental Health Australia chief executive Frank Quinlan??? said it was vital that more research such as this was done regularly, and Australia desperately needed a new mental health plan to tackle the problem and more school counsellors to be employed.
But he said it was pleasing to see more children seeking help.
"  Maybe it means young people are more aware of mental health issues, and as a father ??? I would definitely say my children are much more aware of mental health issues than I was," he said. 
Help is available: Lifeline 13 11 14 or Headspace https://www.eheadspace.org.au/