More than three-quarters of teachers (77 per cent) say poor mental health is having a detrimental impact on pupils’ progress.

The survey was carried out by researchers at Leeds Beckett University in West Yorkshire.

In a poll of around 775 teachers, almost all (94 per cent) said their energy levels in the classroom drop during periods of poor mental health, while nine in 10 said their teaching is less creative during these times.

These periods are often caused by “excessive workload and constant work scrutiny”, said researchers.

Other symptoms of poor teacher mental health include “lower levels of tolerance”, “focusing on the negative”, and being “quick to anger”.

However, only a quarter of those questioned say their illness has been identified by a GP or medical professional.

Professor Jonathan Glazzard, of Leeds Beckett University’s Carnegie School of Education, said: “Teaching is a fantastic profession that transforms the lives of young people and of course we want people to become teachers.

“At the same time, we need to make them aware of the issues they will encounter. The results of this survey are quite clear, and it’s time the Government and school leaders took action over reducing workload.”

Joe Carter, Group Editor at Teachwire.net, added: “We speak to an increasing number of schools that are putting in place practices to help safeguard the mental health of staff and pupils. What this survey shows is that investing time and resources into such activities is not only justified in terms of improving teacher wellbeing and staff retention, it’s an important part of any school improvement plan when it comes to students’ progress and attainment.”