The findings were laid out in a report Tuesday by Ofsted, an education standards watchdog which monitors schools in England. Ofsted employees carried out the assessment by visiting more than 900 education and social care providers during September and October.
Some children in the earliest years of education had to return to nappies despite having been potty-trained, according to the report, while many in the same age group also lost early progress with words and numbers.
"Among older children, inspectors heard that many now lack stamina in reading and writing; some have lost physical fitness; and others are showing signs of mental distress, manifesting in an increase in eating disorders and self-harm," the report added.
Chief Education Inspector Amanda Spielman said the decision to keep schools open during England’s second national lockdown in November was “very good news indeed."
"The impact of school closures in the summer will be felt for some time to come – and not just in terms of education, but in all the ways they impact on the lives of young people," Spielman added.
Despite educational institutions reopening this autumn, an increasing number of parents are choosing to homeschool. Teachers say parents are motivated by virus fears, as opposed to a commitment to delivering robust home education.
Ofsted said it was also concerned about a fall in referrals to social services, which raises alarm bells that abuse may be going undetected.