Childline said they have dealt with at least 16,644 counselling sessions with children over their mental health concerns between the start of lockdown on March 23 and May 10.
The NSPCC, which runs the support line, said this was more than half of the total 30,868 sessions delivered during the seven-week period.
This equates to around 339 sessions a day, or roughly around once every five minutes.
In comparison to the 2018-19 financial year, a total of 71,283 counselling sessions were held for children with mental health concerns in the UK.
This means the service has delivered 43 per cent of last year’s total mental health counselling sessions within seven weeks.
Of the sessions delivered since March 23:
Some 36 per cent of sessions during the lockdown mentioned concerns about mental or emotional health
13 per cent touched on suicidal thoughts and feelings
12 per cent on family relationships
six per cent on self-harm
four per cent on sex, relationships and puberty.
Around 120 sessions mentioned coronavirus on average each day, with 5,880 sessions – around a fifth of the total – taking place during lockdown.
Between January 10, the first time a child mentioned coronavirus when contacting Childline, and May 10, there were 6,938 sessions delivered which mentioned coronavirus.
The NSPCC also said use of Childline’s Calm Zone, an online tool to help young people manage their feelings, had increased four fold during lockdown.
In early March, it was being accessed around 2,400 times a week, rising to 10,000 weekly page views in April.
It is urging the public to donate to its urgent appeal, Still Here for Children, launched in April.
Dame Esther Rantzen, who founded Childline, said: “We know from the counselling sessions we have delivered that children’s mental health has been directly impacted and those children who are living in homes which are not safe – where there is violence, addiction or abuse – are finding it especially difficult during lockdown.”
She added: “We are urging the public to support our Still Here for Children appeal so we can continue to support our young people whose lives have changed overnight.”
Childlike, a counselling service for children, said there had been little change in concerns pre and post-lockdown, but said the crisis had exacerbated young people’s anxities.
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