Schools have been warned to look out for serious mental health problems among their pupils as they open their doors for the first time since January.
The chief inspector of Ofsted, Amanda Spielman, said remote learning had been a slog for many and that issues like self-harm and eating disorders were on the rise.
Those fears appeared to be echoed by Boris Johnson as he tried to ease the concerns of parents worried about sending their children back to the classroom.
The prime minister said that the risk lay “actually in not going back to school tomorrow, given all the suffering, all the loss of learning we have seen”.
Mr Johnson shut schools in England at the start of the year as cases of Covid-19 soared.
The decision to reopen them marks the first step in the government’s roadmap to return the country to normality.
But experts have warned the move could lead to a new spike in cases.
Mr Johnson said he believes pupils, parents and teachers are ready to return.
But Ms Spielman warned schools and parents they had to be alert to the fact that serious mental health difficulties would persist even after face-to-face classes resume.
She said pupils had endured “boredom, loneliness, misery and anxiety” over the last two months.
“There is a minority – and let’s hope it is not too large a minority – whose problems have increased and it is really important that we are good at recognising where problems are arising,” she said.
“Things like eating disorders, things like self-harm, and mental health services are very aware of the kinds of problems that have been increasing and whether they can expect more cases coming through, so everybody needs to be alert to these," she told Sky News’s Sophy Ridge on Sunday programme.
Her warning comes as experts wrangle over how to help children “catch up” on lessons they have missed because of lockdown.
Labour has called for “breakfast clubs” while the education secretary has suggested pupils could soon face a longer school day as experts wrangle with how to help children catch up after lockdown.
Other options could include a five-term school year, an idea Gavin Williamson floated last week.
The changes would be designed to help pupils to catch up on what they missed during the coronavirus pandemic.
But the head of the government’s schools watchdog appeared to pour cold water on the government’s ideas, suggesting they had not worked in the past.
Mr Williamson told Sophy Ridge on Sunday: “There is a whole range of different proposals that we are looking at, whether it is a five-term year, whether it is lengthening the school day.
“But also measures such as enhancing the support we give to teachers, supporting them in their professional development, making sure they can be the very best of themselves.”
Sir Kevan Collins, the government’s education recovery commissioner, would consider what measures to introduce over the next 18 months, he said.
But Ms Spielman told the same programme the plans could backfire, suggesting that experiments along similar lines in the past had not persisted.
“There’s no point adding time here or moving time there if you don’t get a groundswell of support,” she added.
“If children simply don’t turn up for extra time or summer schools, for example, you could end up putting a lot of effort into something that doesn’t achieve the objective.
“My concern is to make sure that we go with the grain of what parents will embrace to make sure that all children get the very most out of their education.”
Labour has called for catch-up breakfast clubs, which the party says would allow pupils to recover the time with friends as well as teachers.
On a visit to a school in Dagenham, east London, on Monday, Labour leader Sir Keir Starmer and shadow education secretary Kate Green will launch a new “Bright Future Taskforce” designed to deliver a long-term strategy for children’s recovery.
Labour estimates children across England will have lost an average of 109 face-to-face school days because of the pandemic. The party says evidence shows breakfast clubs can boost children’s educational attainment and have a positive impact on reading and writing.
Sir Keir accused ministers of treating children as an “afterthought” throughout the pandemic.