Almost 30% of 16-year-old children in Northern Ireland were bullied at school within a two-month period, according to a new survey.
The Young Life and Times Survey was carried out by researchers from the University of Ulster and Queen's University, Belfast.
It found students bullied at school were more likely to feel pressure to smoke, drink and go on diets.
Dr Dirk Schubotz, project director, said researchers also found that bullying policies within schools could make a real impact.
Meanwhile, a teachers' union has claimed there has been a ten-fold increase in the bullying of teachers in recent years - causing many to leave the profession.
At its annual conference in Newcastle, Co Down, the Irish National Teachers' Organisation called for a commitment by Northern Ireland's Department of Education and employers to give support to teachers.
