As a primary school student, Bex could not understand why she was constantly overwhelmed with feelings of hopelessness.

"You're meant to be playing with dolls and scraping your knees falling over in the playground, not feeling sad all the time," she said. "Those feelings don't make sense to a little kid."

Now 19, the art student from Chippendale has been diagnosed with depression, anxiety, post-traumatic stress disorder and dissociation.

With new research showing almost one in four young Australians are likely to have a serious mental health problem, she believes more open discussion is vital.