Mark* lay in bed, staring at the clock. The alarm had gone off 15 minutes ago, but his limbs felt leaden, his stomach churning and nauseous.
The same sensations of fear and hopelessness had overwhelmed him each morning for months, stalking him throughout his working day - in the corridors, in the staffroom and most particularly in the classroom. And the symptoms had been getting steadily worse for weeks.
"I wandered around the school on legs of treacle, with less and less to say to anyone," he says. "The noise in my classroom was rising steadily by the day; not, of course, the noise of creative learning, but the noise of a mob that was increasingly rampant.
"When I started the job at an inner-city comprehensive, I had seen (the film) To Sir, With Love and wanted to repeat that story. But I had also heard the story of the teacher before me who, by the end, simply stood at the front of the class, whispering to nobody in particular, `You got my wife, but you won't get me.' A year and a half on, I was in the same position."
Mark thought about killing himself but was still mentally and emotionally stable enough to realise that "it wouldn't solve anything". Instead he had a breakdown, sought counselling and, incredibly, some time later, returned to teaching. Twenty-five years on, working in a very different sort of school, he remains a dedicated and effective teacher.
Many other teachers and academics are not so fortunate. Suicide among teachers is increasing - up 80 per cent between 2008 and 2009 (from 35 to 63) - according to the Office for National Statistics. When TES columnist Ms Anne Thrope wrote about suicide recently in this magazine, TES was inundated with responses, prompting a web-chat session about the incidence of stress, depression and suicide in schools.
Indeed, in the past three or four years, there have been some shocking and very public suicides by teachers: the teacher who set himself on fire in Harrogate (he was said to be worried about exam results); a teacher in her thirties who had been teaching for 15 years but calmly walked out of school one day and threw herself under a bus; a headmaster who committed suicide a day before Ofsted inspectors were due; and another who hanged herself before an Ofsted inspection after complaining she was overworked and stressed.
The Teacher Support Network, which runs a teacher helpline, reveals that calls reporting anxiety - often part of, or a prelude to, depression - have doubled from 2010 to 2011. And figures this year are expected to be higher again.
In 2010, 1,331 teachers reported suffering from anxiety; in the first four months of this year alone, the figure has already reached 1,260, according to the Teacher Support Network.
The organisation claims that more teachers are killing themselves - and many more suffering from mental illness - because of the combined stresses of classroom inspections, changing government targets, ever-moving "goalposts" and a 49-hour-plus week (much longer if you are a head or deputy headteacher).
Yet on the face of it, since the shocking suicide figures of 2009, things have calmed down. In 2010 (the most recent figures available), the number of teachers committing suicide had dropped.
The problem has not gone away
However, John Illingworth, former president of the NUT, who, after a breakdown in 2005, now campaigns to raise awareness of mental health issues for teachers, says that authorities are deluded if they believe the problem has faded.
"There was a dramatic spike between 2008 and 2009," he says. "But we have seen such spikes before. That's the pattern. The overall number of teachers committing suicide over the past decade has continued to rise steadily. You can't ignore that."
Illingworth points to a Europe-wide study on occupational stresses facing teachers. The study by the European Trade Union Committee for Education was published earlier this year. It looked at more than 5,400 teachers in 500 schools across Europe, and found that the UK fared badly in nearly all the categories.
It reveals that teachers in the UK had the highest levels of burn-out, the second highest levels of cognitive stress, above average levels of lesson disturbances and higher than average levels of verbal abuse and conflicts with parents.
Teachers in the UK also had the highest quantitative demands placed on them - second only to Portugal - in terms of how much their work impacted on their home life.
In addition, the Health and Safety Executive (HSE) confirms that teachers continue to suffer more than other professions. Whereas most sectors are managing to reduce stress levels, "education and teaching professions continue to report higher levels than other industries and occupations," says an HSE spokesman.
"In the UK, suicide rates in teachers are 40 per cent higher than the average for other occupations," Illingworth says. "But in other European countries it doesn't seem to be the case. In Denmark, for example, teacher suicide rates are lower than the average for other occupations. I want to know why.
"But coroners' reports are confidential and it's difficult to know to what degree the job is responsible for the teacher who commits suicide."
He has now asked MP Vernon Coaker, a former minister of state for schools, to ask in the House of Commons how many teacher suicides have been viewed, by the coroner, as work related.
Ironically, Illingworth says, the teachers most likely to buckle under the pressure of stress and overwork are likely to be the high achievers - perfectionists who are anxious not to short-change their pupils.
"Demands on teachers have continually gone up, while their perception is that control over their working lives has diminished," he says. "A lot of teachers can cope with that. But the most conscientious teachers are chasing a list of `to do' things that are frankly impossible. The job is never finished if you are conscientious. If they are not working, they are thinking about working.
"If you look at the teachers who have committed suicide and what people have said about them - `always available, nothing too much trouble' - this is perfectionism. But it can be at the expense of their health - even their lives."
Yet the government, he claims, has refused to grasp the nettle. "About 40,000 teachers leave mid-career each year and it costs some pound;750 million annually to replace them," Illingworth says.
"They would rather throw teachers out because they are `broken' and buy new ones. No manager in any factory would treat his workers like this - it doesn't even make economic sense. But this is how the government is treating teachers."
A 2010 study by Compass - the Niamh centre for mental health research and policy - appears to support this view. Teachers' Mental Health recounts that although help for stressed teachers is available - on the internet, through GPs and via internet and teacher support helplines - many are too exhausted, depressed or mentally fragile to pursue it.
Based on face-to-face interviews with 39 teachers with mental health problems and meetings with six school managers who had managed teachers with mental health problems, the study concludes that authorities need to be more active in identifying teachers who are suffering - for example, by carrying out regular stress audits.
It recommends working to remove the stigma of mental illness from the culture of schools, offering depressed teachers support in the form of counselling and offering those who have returned from sick leave flexible hours to help ease them back into the classroom - these are recommendations also supported by the NUT.
But the report also identifies the major hurdle to any of these recommendations - money and the consequential fear of headteachers and local authorities that the school would be left with a hefty financial burden.
It's a far cry from France, where teachers are generally more revered than in Britain. There, they have created a unique solution: a government- funded health spa and psychiatric hospital designed to give exhausted teachers the rest and counselling they need to recover and return to the classroom.
La Verriere (The Canopy) clinic, set up in 1951 by teacher Marcel Riviere, is run from a series of bungalows on a sprawling site, 35km from Paris. It is part of an initiative by the French government, begun in 1946, to provide health cover for teachers.
Teachers can be referred by their schools or their doctors. Most treatment courses last between two and six weeks and many teachers return, intermittently, for "top-up" treatment.
"We can treat about 185 people at a time," La Verriere's Benoit Coquille says. "There are about 1,000 clients each year. They stay in bungalows which can have around 15 people, each with their own room, and a shared dining room.
"It does not feel like a hospital. It feels like a series of houses in a small village. People learn that they are not alone with their problems."
Coquille explains that teaching structures and training processes had also changed in France in recent years, leading to an increasing number of teachers seeking relief from stress and burn-out.
"A typical person to go to La Verriere would be aged 35-40," he says. "This is when burn-out most often occurs. A good example might be a woman, a very active teacher for 10 years, who also has children. She's just burned out with exhaustion. She doesn't want to stand up in front of the class any more. This is what is common. Her job is not new, and not old. It has just got harder."
But no such institution exists in Britain - and the suicide attempts continue. Those who survive are often irrevocably scarred - taking equally drastic but very different measures to build themselves a new future.
Chris*, in his late forties, had been a secondary teacher for 10 years. A family man, he enjoyed his home and loved his wife and children. But over the past 12 months he had been quietly finding the mounting pressure at his school "intolerable".
"I had begun having sleepless nights. I lost my appetite and couldn't eat," he confided to a friend.
"It was the targets. I found it impossible to meet them. And when I did, they kept changing. And there were new demands. Everything kept changing."
One day, Chris simply walked out of school. He didn't go home and the police were alerted. For two days nobody knew where he was. It was later discovered that he had taken a massive drugs overdose. He survived and was briefly sectioned. But when he recovered he was so distressed he reinvented his life.
His marriage broke down and he left the area, changing his mobile phone number, email address, indeed anything that would link him to his former life as a teacher.
The friend in whom he had confided says: "I don't know where he is now, and I don't think he wants to be found. The whole experience was so devastating for him he quite literally ran away from the life he had in teaching."
Sue McMahon, branch secretary for the NUT in Calderdale, West Yorkshire, says that she has seen a dramatic rise over the past few years in the number of teachers suffering from mental health problems.
"I would say that in the past three or four years, stress levels of teachers have risen beyond all belief. We've had serious case after serious case. I have a call from someone with work-related stress at least once a week.
"Monitoring of teachers has led to their feeling that they are not in control of their profession. And it's now so target-driven that it has taken the joy out of teaching for a lot of people."
Teacher stress is not a new problem. Back in 2005, the Journal of Managerial Psychology ranked teaching as the second most stressful job out of 26 occupations, including and surpassing that of ambulance drivers.
And it's more than a decade since the first case was brought by a teacher suing the government: Muriel Benson, a head of year at a secondary school in the Wirral, won pound;47,000 compensation for illness caused by stress in an out-of-court settlement in 1999. But since then, the NUT has backed more than 100 cases where teachers have won compensation.
Mark, the teacher whose story was outlined at the beginning of this article, tries not to dwell on the six months of profound depression he suffered before he was forced to seek help.
He still has high ideals for the classroom but says he now sets himself realistic goals. And he believes there is much teachers can do to help themselves. "Understand that teaching is a marathon, not a sprint," he says. "Find the right place and school for you to teach.
"Realise that spending time with young people is a privilege. And don't listen to comments on the internet or in the news saying that teachers are all lazy, mediocre coasters. Even if the government and society don't appreciate you, when teaching goes well, it really is the best job in the world."
* Names have been changed
Assistant headteacher Pat Stack, who was appointed an MBE for his outstanding contribution to education, was only 45 when he was found hanging in an outbuilding, yards from busy classrooms, in 2001. He left four children and a wife, Cathy, who has now become a teacher herself.
She claims that it was the ever- changing demands on teachers that contributed to his death. "His aim was to build pupils' self-esteem but he let his own crumble," she told TES. "His depression started in about 1990, when a project to help under-achieving boys - on which he was working with another teacher - was shelved," she said.
The two teachers were then pitted against one another in a cost-cutting exercise. One stood firm and left teaching for good. "Pat stayed on but felt he had failed his friend, his pupils and himself. He started suffering from depression and losing sleep."
Pat, she revealed, first tried to kill himself in May 2000, with a frayed dressing-gown cord tied to the banisters of the family home. "I was shocked and angry but he was equally shocked and scared. Two hours later, he was standing by our bed, dressed and asking if he should go to work. On his way out, he opened a letter saying he had been nominated for an MBE."
Pat was the first teacher to be in charge of enrichment and extension and, Cathy says, was committed to his pupils and school. But she adds: "He was unable to accept the impossibility of implementing the plethora of incentives being thrown at him. He would wake at 3am with a head whirring with ideas. He was an extremely caring teacher. But at the start of each term the fear of survival started to build up."
How to beat stress
Understand that teaching is a marathon, not a sprint. Pace yourself.
Find the right place to teach. If you are not a natural disciplinarian, find a school where students are better behaved. Don't fight your natural instincts.
Have a circuit-breaker mechanism in place. If your stress levels rise to such an extent that your mental health is threatened, take a day off. It's better from your pupils' point of view if you choose to take one day off, rather than being forced to take six months.
Try to exercise for 15 minutes each night.
Take your spiritual life more seriously and yourself less seriously.
Protect your sleep patterns.
Decide on the average number of hours during term-time that a full-time teacher in your position should morally work each week not counting breaks, and regard time outside that as yours.
Don't listen to comments that teachers are all lazy mediocre coasters. Your students are the people who count.
Links to practical support and resources for helping to manage your mental health: