Headteachers are calling for new social media laws to keep children safe, amid concerns that pupils' use of these sites is harming their mental health.
Most school leaders have received reports of pupils being bullied or being exposed to unsuitable material – such as sexual content or hate speech – with some saying that this is happening on a daily or weekly basis, according to a small-scale poll by the Association of School and College Leaders.
Concerns were also raised about parents' behaviour on social media.
The union, which meets for its annual conference in Birmingham today, said more needs to be done to protect young people.
In the poll, which questioned 460 secondary school heads across England, Wales and Northern Ireland in January, 95 per cent of respondents said they believed that the mental health and wellbeing of pupils has suffered as a result of social media use over the past 12 months.
Nearly all of those polled said that they had received reports of pupils being bullied on social media, with 40 per cent saying incidents were reported on a daily or weekly basis. Almost all had received reports of pupils encountering material including sexual content, self-harm, bullying or hate speech, with 27 per cent saying this was reported on a daily or weekly basis.
More than nine in 10 (93 per cent) said new laws and regulations should be introduced to ensure that social media sites keep children safe, while three-quarters (77 per cent) thought that the government and social media firms should produce more information for parents.
Government plans 'don't go far enough'
The government has said it wants the UK to be "the safest place in the world to be online" and has announced it will introduce a new code of practice this year, setting out the minimum expectations for social media companies.
One headteacher raised concerns that while their school educates students about social media and sets rules on acceptable use, parents do not do so at home.
"A very small number of parents also behave badly on social media," the head said.
"When the school arranges e-safety meetings for parents there is very limited attendance. A national campaign to educate parents and alert them to the dangers of social media would support the education that is happening in schools for students."
Another told ASCL: "Far too frequently parents join in with trolling or abuse incidents or model abusive or harmful social media behaviour to their children themselves; the classic example being parents wading in on social media with threats of violence or confrontation to 'protect' their own child."
ASCL general secretary Geoff Barton is expected to tell the conference on Saturday: "Social media can be a force for good, helping young people to connect with each other in a positive manner.
"But it also has a dark side which can be seen only too clearly from our survey.
"It is a technology which has grown at great speed, outstripping our ability as a society to understand and mitigate against these negative impacts. More must be done to protect young people so that they can enjoy social media safely and responsibly.
"We recognise that the government is trying to find solutions, but we are not convinced that the current proposals go far enough."