Some 13% of 16-year-olds have admitted self-harming in the last year.
The finding is just one contained in new research carried out by Queen' University Belfast.
Almost a third of teenagers say they have experienced serious mental health problems in the last 12 months. Some 86% said they felt stressed in school.
A total of 1,367 16-year-olds from across the North took part in the survey.
Dr Dirk Schubotz from Queen’s University carried out the research. He said: "This a growing issue. They feel tremendously stressed. It's something we really have to take seriously."