Bullying is far more widespread in schools than previously thought, with three-quarters of a school's population taking part in bullying and girls suffering the most.
The startling findings, revealed at the recent annual conference of Respectme, Scotland's anti-bullying service, appear to support the view that anti-bullying initiatives should be aimed at most pupils, not just a minority.
Researchers from Edinburgh and York universities emphasised that anti-bullying work should not merely focus on the bully or victim, but also take account of the impact on bystanders, whom they defined as people who are not active bullies or direct victims but still have a role in bullying.
They also called for a recognition that bullies can experience psychological distress similar to victims'.
The research assessed 1,993 pupils aged 12 to 19 at 14 schools in the north of England, describing the results as "one of the most comprehensive views of the mental health of British school pupils who are victims, perpetrators, andor bystanders in bullying behaviour".
Significantly more girls than boys reported being in the role of bystander when bullying took place, and the level of psychological distress reported by girls was striking.
Their scores for five forms of psychological distress all indicated that witnessing bullying, or taking a passive or secondary role when another person was being bullied - such as standing by or goading the bully on - could have "a significant impact upon mental health".
"It's really worrying to me what's happening with girls in the 12-16 age group," said Ian Rivers, of Edinburgh's Queen Margaret University, who carried out the study with Nathalie Noret, a researcher at York St John University.
In some cases the differences between boys and girls were huge, particularly for girls deemed both bully and victim.
The researchers found that girls:
- were 12 times more likely to indicate symptoms of "interpersonal sensitivity" (over-reaction to things other people say);
- reported symptoms of somatisation (conversion of an emotional, mental or psychosocial problem into a physical complaint) nine times more often;
- were six times more likely to report symptoms of psychotic behaviour.
The researchers' report underlines the significance of the 74 per cent figure. "Anti-bullying initiatives that successfully reduce and sustain a continued decrease in bullying over time are likely to benefit the mental health of the majority of pupils at school, and not just bullies and victims," it says.