School closures in England during the Covid lockdown badly damaged the mental health of mothers but had no impact on fathers’ wellbeing, research has found.

Doing childcare and home schooling as well as their own jobs led to more mothers of pre-teenage children feeling depressed, having trouble sleeping and seeing themselves as worthless.

The pandemic increased mental health problems among parents generally. However, mothers bore the brunt, with fathers barely affected, the study found.

Closing schools to stop the spread of coronavirus had “a significant detrimental effect” on mothers’ mental health, academics from Essex, Surrey and Birmingham universities said. However, “for fathers it made no difference”.

The findings are based on a study of how 1,500 parents of children aged between four and 12 in England coped mentally with the school closures that accompanied the first lockdown, which began in March 2020. It looks at the differences in impact between parents whose children were allowed back to school at the start of June – primary school pupils in reception and years one and six – and those whose offspring did not return until September.

Mothers whose sons and daughters missed the entire summer term were worst affected. Their responses to 12 questions in the general health questionnaire, an established way of measuring mental wellbeing, showed a major decline compared with before the pandemic began.

The researchers found that mothers with at least one child who was not among the year groups prioritised to return to school last June “are more likely to report losing more sleep to worry, to feel constantly under strain; to feel like they can’t overcome their difficulties; [and] to feel unhappy or depressed”, they say in a report for the institute for social and economic research (ISER) at Essex University.

Other effects included women losing confidence in themselves, thinking of themselves as worthless and feeling unable to enjoy their normal day-to-day activities.

“The impact of having children out of school on mothers’ mental health is substantial, and an important hidden cost of lockdown. Our study shows – for the first time – the strain of school closures on mothers’ mental health,” said Dr Laura Fumagalli, a research fellow at the ISER and one of the report’s four co-authors.

“We estimate that school closures could be responsible for around half of the decline in mental health experienced by mothers during the pandemic. It is striking that on average fathers’ mental health does not seem to be affected by school closures,” she added.

The authors identified a sharp increase in loneliness, social isolation and the loss of contact with peers both at and outside school as the key trigger for mothers’ decline in mental health. That was more important than having to work extra hours or losing a job, they found.

Mothers whose children were not prioritised to go back to school were more likely to report feeling lonely than those whose children returned in June.

The findings tally with previous research showing that women generally, and mothers living with young children in particular, were among the groups who suffered an increase in mental distress during the pandemic, as did people with poor underlying health, those in low-income households and people of Asian descent. It is the latest study to find that men’s mental health remained largely unchanged.

“The findings of this study are incredibly concerning. Incredible parents, in particular mothers who disproportionately shouldered the colossal burden of juggling home schooling and work during the pandemic, are physically and mentally exhausted,” said the Liberal Democrat MP Munira Wilson, her party’s spokesperson on health, wellbeing and social care.

“Maternal mental health has suffered gravely through multiple lockdowns, and lacklustre support from the government has simply not helped matters.

“Their botched reopening of schools, in which they failed to take on board the concerns of parents over unclear and inconsistent guidance, is just one example of how the government has utterly failed mothers during a period of great distress.

“Mums must feel like they have had the rug swept out from underneath them. The forthcoming public inquiry into the handling of the pandemic must look into its impact on mental health as a matter of priority,” Wilson added.

The data about the 1,500 parents in the study came from Understanding Society, the UK Longitudinal Study, and was collected in April, May, June, July, September and November last year.