At least 214 teachers in London have gone on long-term stress leave in the past year, Liberal Democrat research has revealed.
The Liberal Democrats said the figures "laid bare the impossible pressures teachers are under" and warned that stress caused by an obsession with exam results is fuelling the teacher recruitment crisis.
46,000 days have been taken off by teachers for stress and mental health reasons in London in the last four years, including over 12,620 in 2016/17.
Bexley had the highest number of teachers on long-term stress leave, with 73 taking leave of one month or more in 2016/17 for stress and mental health reasons.
The figures are based on responses to Freedom of Information requests by the Liberal Democrats from 10 London boroughs, meaning the real figure is likely to be substantially higher.
The responses suggest one in 84 teachers in the capital is now on long-term leave of one month or more for stress and mental health issues.
Tom Brake MP, Liberal Democrat for Carshalton & Wallington, commented:
“These figures lay bare the impossible pressures our teachers are being put under.
“It is simply unacceptable that those working tirelessly to do the best for our children are seeing their mental ill-health affected as a result.
“We've heard story after story of teachers experiencing 'burn out' due to factors including work-load or mishandled Ofsted inspections. But these are no longer just the rare or most extreme cases - they are increasingly common.
“This must be a wake-up call to the new Education Secretary Damian Hinds.
"Stress and anxiety are fuelling the teacher recruitment and retention crisis, but the government’s current approach is making matters worse.
“We need fundamental reform of assessments and inspections in our schools, which are two of the greatest sources of anxiety for teachers.
“It is completely wrong that teachers are made to feel that they will be judged a success or a failure based on a single bad inspection or a class that doesn't perform as well as expected.
“The Government must also end the real-term cuts to pay for teachers that are leaving them feeling overworked and undervalued."