Almost 30% of 16-year-olds in Northern Ireland were bullied at school within a two month period, according to a new survey.
Bullying affects one in three children
The Young Life and Times Survey was carried out by NI's two universities.
It found students bullied at school were more likely to feel pressure to smoke, drink and go on diets.
Dr Dirk Schubotz - the director of the project - said researchers also found that bullying policies within schools could make a real impact.
Meanwhile, a leading teachers' union has claimed there has been a 10-fold increase in the bullying of teachers in recent years.
This had caused many to leave the profession.
At their annual conference, the Irish National Teachers Organisation called for a commitment by the Department of Education and employers to give support to teachers.