The UK is “sleepwalking into a crisis of childhood” with youngsters struggling to cope with the pressure to achieve at school, fit in with their peers and cope with wider anxieties over issues such as Brexit, poverty and the climate crisis.

A survey of 5,000 children, parents and grandparents by the charity Action for Children found a strong shared perception that modern childhoods were getting worse amid what the charity called unprecedented social pressures.

Two-thirds of parents and grandparents felt childhood was getting worse, and a third of children agreed. All agreed bullying – both online and offline – was the main problem, followed by pressure to fit in socially, which had become more intense as a result of social media.

Children from low-income families were significantly more likely than their wealthier counterparts to report worries about a range of issues from bullying to mental health, although children from all backgrounds were vulnerable to these anxieties.

Nine out of 10 children – some as young as 11 – said they worried about “adult” issues. Roughly half said they were anxious about poverty and homelessness, terrorism, inequality and the environment, while about four in 10 worried about Brexit, sexism and racism.

Julie Bentley, the Action for Children chief executive, said: “The country is sleepwalking into a crisis in childhood and, far from being carefree, our children are buckling under the weight of unprecedented social pressures, global turmoil and a void in government policy which should keep them well and safe.

“Our research shows children worry about poverty, homelessness and terrorism, and the vulnerable children we work with every day are facing traumas like domestic abuse or neglect, going hungry or struggling with their mental health, without the support they desperately need.”

Bentley called on the government to establish a national childhood strategy and reinvest in council children’s services, whose funding was cut by a third between 2010 and 2017. “For the past decade the government has been asleep on the job when it comes to investing in our children,” Bentley said.

The education secretary, Damian Hinds, said: “Although in many ways this is the best time yet to be young, I certainly recognise the pressures and worries young people feel. Growing up has never been easy, but technology and social media can exacerbate the need to fit in and the perception of others’ perfect lives, as well as make it harder to leave being bullied behind at the school gates.

“But we are equipping young people for adulthood in a changing world, by identifying mental health problems and providing support in schools, encouraging young people to gain resilience and skills through activities such as sport and music, and teaching young people in school how to navigate the online world safely and constructively.”

Children from low income families were strikingly more pessimistic about their childhoods: 39% thought childhood was getting worse, compared to 25% from higher income backgrounds. Poorer children were significantly more likely to worry about not having enough money (44% to 18%).

By the same token, the poorest children had greater concerns about their mental health (31% compared to 20% of those from higher income families), and were also more likely to be worried about the mental and physical health of family and friends (34% to 24%).

Louise Baroy, 43, a single parent from Newcastle, said she felt her children worried more, and about more things, than she had when she was young. “They ask me things like: ‘Will the world still be here when I’m older?’ or: ‘Are we poor?’ I have to sit down and talk to them to put things in perspective. I say we’ll always be OK, because you have got me. We are poor but so are a lot of people, and it doesn’t matter.”

Steve Reed MP, Labour’s Shadow Minister for Children, commenting on the report, said:

“Tory and Lib Dem cuts to children’s services and help for struggling families have contributed to a national crisis facing our children, with one in three councils warning they no longer have the funding they need to safeguard the most vulnerable.

“No society that loves its children can treat them like this. The Government must learn the lessons of this hard-hitting report and make Britain’s children their priority rather than giveaways for the super-rich.”

• This article was amended on 9 July 2019 to add a comment from the Labour party.