One in five children in the world suffers from mental illness or behaviour problems, it's been warned.
Two world organisations say there are far too many children living with things like depression and stress, and this could lead to them having serious health problems in the future.
The World Health Organisation (WHO) and the United Nations Children's Fund think all these problems are caused by living in war zones, being poor and all the changes that young people have to cope with in today's society.
'Ticking time-bomb'
Children in an Afghan refugee camp
They're particularly worried about the world's teenagers, who are more likely to think about suicide.
Children who are depressed are also more likely to be ill when they get older.
A WHO spokeswoman said the amount of children with mental illness was a "ticking time-bomb", and millions of children could grow up to be ill adults unless something is done to help them.
Hear Story
Chat about this now!
