In the fast-moving world of modern education, teachers have to be experts in more than one subject.

They need to be administrators, accountants, managers, team leaders, counsellors, arbitrators, social workers and secretaries - and the strain of taking on different skills has started to show.

A recent study by researchers at the University of Sussex has shown some teachers are nearing breaking point as the stress of their profession becomes too much to bear.

The study also reveals how the profession is heading for a crisis, with many teachers staying away from senior positions to avoid even higher levels of stress.

Education specialist Vivienne Griffiths said the trend could prove damaging to the quality of teaching.

She said: "People want to stay in the profession but they don't have ambitions to be anything higher than a subject co-ordinator.

"They don't want more responsibility, which could have drastic implications because there is already a shortage of headteachers."

The study shows 35 per cent of primary teachers who qualified from the University of Sussex between 1990 and 1993 were either aiming for headships or working as heads.

But of those teachers who trained between 1993 and 1996, only one per cent were aiming for headships.

The declining figures cause concern for heads and classroom teachers.

Paul Shellard, former president of Brighton and Hove Teachers' Association, said he was not surprised by the findings.

He said: "There's already a crisis. A number of headships do not have the high numbers of people applying you might have expected.

"Often you would expect only two or three people to apply whereas previously you would have been expecting a much higher number.

"The concern is that people who would potentially make very good headteachers are being discouraged because of the responsibilities of the job."

Even headteachers who love their jobs do not deny they are stressed.

Liz Fletcher, head of Patcham High School, said: "It should and can be the most wonderful job in the world.

"But there has been an increasing burden of responsibility and this has distanced teaching from working with children, which is the most rewarding and important part of the job.

"Raising standards is crucial but heads are now being pushed away from the part of the job many find most rewarding.

"I think there should be a structure to involve more people in school policy and responsibility. Leadership is about team work. If responsibility was shared, heads would have more contact with children."

But heads are not the only teachers to feel their time with children has been stripped away.

Trish de Lima was former head of art at Marina High School, now East Brighton College of Media Arts.

The added pressures of Ofsted inspections and new Government initiatives drove her out of the profession and into a nervous breakdown.

She said: "The responsibilities for a head of department were incredible. I just wanted to teach but there was so much paperwork it hardly left time for the things that were important.

"I feel the kids were neglected. I don't think they were getting the standard of teaching they deserved. I had a nervous breakdown that was partly because of the stress. I have retired now."

Mrs de Lima, 58, taught for a while in Surrey after leaving Marina High but she said the damage had been done.

"I miss teaching dreadfully. I adore it. I think it can be a worthwhile and wonderful job but not the way it is going."

Tim Lucas of the National Union of Teachers said the lack of candidates for headships was not the only serious problem associated with teachers' stress.

He said implementing Government strategies like literacy and numeracy hour, preparing for Ofsted inspections and media criticism had led to many teachers taking early retirement or long-term sick leave.

He said: "The Government keeps making reassuring noises about work loads and paper work, but things seem to be getting worse not better."

Angela Jacklin, who conducted the two-year study with Dr Griffiths, agreed the work level had risen rapidly.

She said: "Teachers want to stay in the job but it has become too pressured."

Dr Griffiths and Dr Jacklin have now received a £35,000 grant to track the career paths of a group of recently-qualified teachers in the Brighton and Hove area.