One in ten children aged five to 16 have a clinically diagnosed mental health disorder, according to the Office for National Statistics.
ITV News' Health Editor Rachel Younger recently spent the day at the children and adolescent unit at South West London & St George’s Mental Health NHS Trust.
She spoke to past and present patients who are battling a range of issues from depression to anorexia but who are now on the road to recovery.
Raymond Piper, 14, left the unit a week ago, after spending six months there for treatment for anorexia.
At his lowest point, he says he was so full of despair that he "didn't care about life. I didn't care about dying or anything".
It took three attempts to get him into the unit and Raymond's mother Deborah said she was left feeling "helpless" and "isolated" as watched her son "deteriorate physically".
At one point Raymond's condition got so bad, doctors recommended him for dialysis.
"It was at that point that I put up my hands and I said I can't do it any more, he needs the help. I was scared I was going to lose him", Deborah said.
Raymond's father said: "The conflict was just so much that myself and Raymond couldn't be in the same room. The arguments just went off the charts...
"When he was isolating himself in the room, we didn't know what he was up to, we couldn't go into his room because we would be chased out again."
Eighteen-year-old Cerys Grainger, who has struggled with anorexia and self-harm, spent nearly eight months in the unit.
She first became aware something was wrong in 2013.
The teenager had been in the middle of her GCSEs which were "pretty stressful" and says she had "no form of controlling anything else in my head".
"By restricting my food, I was in charge of it and it was something I could do, nobody else could control what you put in your mouth", she said.
"I cut my arms...aerosol burns, scratched, just anything from superficial to needing to needed stitches", she added.
Cerys also spoke of the "absolute nightmare" of adjusting to receiving treatment at the unit: "I hated it at first, being forced to eat, I had no control...from believing you had all the control in your head to handing it all over to somebody else.
"But the structure of it helped", she added.
The Trust also provides the only specialist unit in Europe for mentally ill deaf children and adolescents.
Former patient Jamal Ajala, sought help from Corner House after feeling "down all the time".
"I was really upset, depressed, I just felt like I could fall down anytime", the 20-year-old said.
David Bradley, Chief Executive of South West London and St George's Mental Health NHS Trust, said the pressure of delivering services was "as tough as I've ever known it".
"The demand, the severity and just the pressures on mental health services are increasing, he added.
"We face a daily challenge of making sure we have enough beds for the people who need to be admitted and making sure they are are admitted in a safe and timely way."