The number of teachers taking sick leave due to stress has doubled in the past two years, a new survey has reported.
More than a quarter of respondents said they had taken at least one day off because of stress in the previous 12 months.
More than one in ten called in sick for between two and five days during the same period, the poll of 1,000 teachers for Teachers TV found.
A similar poll in 2007, also commissioned by the TV channel, found that 13 per cent of teachers had taken sick leave due to stress.
More than four out of five teachers said this year that they believed teaching was more stressful than other jobs, with symptoms including anxiety, depression, insomnia and high blood pressure.
Overall, 44 per cent of teachers said they had suffered from stress- related illnesses due to work.
In extreme cases, some have suffered from stress-related angina and ME.
Concerns were raised that some teachers are embarrassed to seek help from senior staff when they are suffering from stress.
Forty per cent of respondents said they did not make their school aware of the problem, with embarrassment and concerns over privacy cited as the main reasons.
Almost a quarter said they did not believe their school would be supportive and a further 8 per cent said they feared they would lose their jobs.
Julian Stanley, chief executive of the Teacher Support Network charity, said there should be a culture change in schools to make teachers feel confident about seeking help.
"There needs to be better training for school leaders to improve their understanding of these mental health problems," said Mr Stanley.
"School leaders should support teachers personally as well as professionally.
"There needs to be a culture where teachers feel confident in asking for assistance without fear that they will be seen as incompetent."
The Teacher Support Network is currently carrying out work with the Training and Development Agency for Schools to improve training and help teachers to better recognise the impact of stress and how to cope with it.
More than half of respondents in the Teachers TV survey said they had considered leaving the profession because of stress, an increase of 5 per cent in the past two years.
But nearly two-thirds said that job satisfaction stopped them from quitting and more than seven in ten said that long holidays helped to compensate for stress levels.
The recession also accounted for some teachers remaining in the job, with 14 per cent saying there were no realistic alternative jobs in the current economic climate.
Andrew Bethell, chief executive of Teachers TV, said: "It is encouraging to see that the large majority of staff stay in the profession because of the job satisfaction despite the challenges of the role and the worrying increase of stress cited by teachers since we asked the questions two years ago."