A new study has found that students who witness high school violence can have long-term mental health and academic problems, similar to being directly bullied.
Professor Michael Janosz from the Université de Montréal, and his colleagues from Belgium and France, conducted a longitudinal study of nearly 4,000 Quebec high school students.
They tested the link between witnessing school violence at age 13 and subsequent antisocial behaviour, emotional distress and academic performance at age 15.
They also compared the impact of witnessing different forms of school violence (such as physical assaults, carrying weapons, vandalism, theft, threats and insults), compared to being bullied over the long term, and the impact it had on each student.
The team discovered that witnessing bullying in all its forms impacted the teens and resulted in higher drug use, social anxiety, depression, delinquency and decreased engagement at school.
Professor Janosz said most students reported witnessing violence at school.
"It is clear that approaches to prevention and intervention should include witnesses as well as victims and perpetrators and target all forms of school violence," he said.
"More importantly, schools should seek to empower bystander students who are not directly involved in acts of school violence, rather than giving them messages to stay uninvolved.
"Schools need to understand that discouraging student involvement can be interpreted by youth as promoting self-centeredness at the expense of community well-being. Nobody should feel powerless."
Trish Corbett, author of How To Raise Kids With Integrity, said when people witness bullying it impacts on them negatively.
"Bullying is harmful to the witnesses too, as they may feel intimidated and recognise in themselves that they do not have the courage or confidence to stand up for another human being who is being treated badly," Ms Corbett said.
"This is a feeling of powerlessness and affects how you feel about yourself which may lead to depression and a feeling of anxiety as you fear coming into contact with, or becoming a victim of the person who bullies."
According to Mrs Corbett, when a person feels powerless to stop or prevent others who treat people in a way they do not personally value, they start to question the strength of their own integrity.
As a result, children and teens should be given strategies to build resilience, confidence and develop a strong self-identity. And the school needs to build a supportive community.
"It is important that teachers and the school have a united understanding of behaviour that is, and is not, accepted in the school yard," Mrs Corbett explains.
"This needs to be communicated in a way that children know is a constant expectation of the culture of the school - as opposed to just a 'new strategy' being implemented to overcome bullying.
"Consistency and education is the key."
A comprehensive approach to bullying
CEO of Interrelate, Patricia Occelli, said it was important for schools to develop a comprehensive approach to bullying in order to create a positive school culture.
"By having open and honest conversations with students about bullying and exploring the fear, guilt, shame and conflicting emotions that bystanders can experience, students can start to learn the importance of the role of the bystander in creating a school culture that encourages the notion that bullying is everyone's responsibility," she said.
The not-for-profit organisation provides school programs that tackle bullying and knows the importance of a whole of school approach to the issue.
"Often we find simply educating the students is not enough, as many attitudes the students hold come from the adults at home, hence educating the whole school community has proven to provide a more sustainable environment for change," Ms Occelli said.
"This approach involves promoting a positive school culture and educating children about the role of bystanders with the aim of promoting the notion that bullying is everyone's responsibility."