Half of teachers in England have considered quitting the profession because of stress, a survey suggests.
Teachers have benefited from a workload reduction agreement
Two thirds of the 823 teachers polled online felt stressed by teaching, half of them during lessons - the biggest cause being disrespectful pupils.
One in 10 told the researchers for Teachers' TV they worked longer hours than EU rules permit - and 60% blamed the amount of paperwork required.
The government insists it has worked hard to support teachers.
When asked about what caused stress, 71% of teachers cited a lack of respect from pupils.
Just under four out of 10 blamed stress on poor resources in the classroom and 44% said they were stressed because of large class sizes.
And half blamed stress in the classroom on pupils' use of electronic gadgets.
Three-quarters said they felt inadequately supported by their head teacher or senior management in dealing with stress.
Andrew Bethell, chief executive of Teachers' TV, said: "Teaching is one of the most demanding professions and it is clear that our teachers are feeling the pressure.
"We need to ensure that there are systems in place to help those teachers who experience stress to access available resources and support networks."
The results of the poll are released as a week to highlight stress among teachers and how to tackle it begins on the government-funded channel.
A Department for Education and Skills spokesman said the government had worked hard to reduce teachers' workload.
"We have introduced an afternoon per week out of the classroom for all teachers to plan and prepare their lessons, doubled the number of support staff who take administrative tasks away from teachers, slashed the bureaucratic burden on schools and ensured that a low limit has been put on the number of hours a teacher can be expected to cover for colleagues.
"In addition, we have given powers to teachers and heads to ensure that they can discipline pupils, remove them from class, confiscate items and exclude where necessary. Poor behaviour should not be tolerated."
Chief executive of the Teacher Support Network Patrick Nash said stress was "the main emotional state teachers report they feel".
"Stress is a symptom, not a cause, of a problem so Teacher Support Network's counsellors and coaches first work with teachers who contact us to find out what the underlying reasons for the stress are.
"Then they seek ways to resolve the issue, perhaps by referring to the union, as well as exploring methods of coping with the physical symptoms to try to prevent sickness absence or even ill-health retirement."