It’s 3.30pm. You haven’t sat down all day, you’re dying for a drink and your sandwiches are uneaten. Your head is pounding and if someone asks for one more thing you’ll scream. “I’m depressed,” you mutter as you eye your marking pile mountain. But are you depressed or simply under pressure?

The link between work and depression is well documented. Research published by the Health amp; Safety Executive (HSE) confirms that teaching is one of the most stressful occupations in Britain, with two in five teachers reporting symptoms. According to figures published by the Teacher Support Network, 49 per cent of applications for retirement due to ill-health cite psychiatric reasons. And Teacherline, a telephone counselling service for teachers, reports that 27 per cent of calls received each month relate to stress, anxiety and depression.

So, how can you tell if you’re depressed or just feeling blue?

“When we are feeling overburdened, we experience negative emotions, and whilst unpleasant, they are perfectly natural and should not be confused with depression,” says Dr Kristina Downing-Orr, author of What To Do If You’re Burned Out And Blue - The Essential Guide To Getting Over Depression (Harper Collins, pound;7.99). “There is a significant difference between the common understanding of depression and that of clinical psychology.The term is bandied about so much that we tend to equate it with an extreme state of sadness, but depression is a serious biological and physiological disorder. The symptoms are so overwhelming, that sufferers just can’t see the light at the end of the tunnel.”

Downing-Orr identifies the following symptoms of depression: l sleep problems l appetite problems l loss of libidol social withdrawall extreme fatiguel headachesl motivation problemsl forgetfulness.

Most of us will experience one or more of these symptoms from time to time, so how do we recognise clinical depression?

“As a general rule, if a number of these symptoms persist for more than two weeks, you may be suffering from depression and should consult a doctor,” says Downing-Orr.

“Teachers are particularly prone to depression because they suffer an enormous amount of stress in their day-to-day lives. It is particularly stressful for trainee and newly qualified teachers because they continually find themselves on unfamiliar ground.”

Helen Matthews, a primary school teacher, suffered a period of depression in her first post: “I started teaching in a small school and I soon began to feel isolated. I felt like my headteacher was picking on me. She discussed my shortcomings at staff meetings. I felt humiliated.”

By the summer term, Matthews was suffering sleep and appetite problems, frequent headaches and had lost the desire to socialise. “At college, I was a party animal,” she explains. “By the end of my first year of teaching, I was too tired to go out at weekends and convinced no one would want to talk to me because I was so miserable.”

“If you think you might be suffering from depression, you must consult your GP,” says Downing-Orr. “Talking it over often alleviates the strain.”

Common treatments include anti-depressants and cognitive behaviour therapy - a form of psychotherapy in which the therapist enables patients to explore issues, using open questioning techniques.

Matthews consulted her GP, who diagnosed depression and prescribed anti-depressants. Two years on, she teaches at a larger school and is enjoying her job.“I used to think that only certain kinds of people became depressed,” she explains.“But now I realise it can happen to anyone, particularly in a high-stress occupation like teaching. I also worried that a history of depression would prevent me from getting a new job.”

Such a history should not exclude people from training or working as a teacher. As Geoff Wybar, head of Gravesend Grammar School, puts it: “Any appointments we make depend on the quality of the teacher. We are all susceptible to the stresses and strains of the job and many headteachers will support recovering colleagues. ” Training institutions make judgements based on the overall profile of an applicant. “We have had a number of trainees with a history of depression or mental illness and many complete the course successfully,” says Andy Jones, leader of secondary programmes at the Instititute of Education, Manchester Metropolitan University. The illness is discussed at interview stage and a medical check is required before the student registers on a course. A letter is also required from the students’ GP or consultant stating that they have recovered.

“We do have to be stringent,” explains Jones. “Schools are tough places and teachers have to be made of strong stuff because stress can act as a trigger for depression. We have to decide if there’s a risk of that happening. If there is, then it might not be the right time for them to train.”

“Burn-out occurs when people are so stressed out they feel unable to perform their job,” says Professor Cary Cooper, Bupa professor of organisational psychology at the University of Manchester Institute of Technology and author of a book on the pressures of the job*.

So why are teachers particularly prone? According to Cooper, poor management and constant change are key factors: “Education is a political football, so new initiatives are introduced all the time. Recruitment and training for leadership can be poor, so change is often managed badly.”

The negative image of teachers has its part to play. Teachers are constantly in the public eye and there is constant pressure from parents and government. Add all this to long unsociable hours and you have a stressed workforce. As Cooper puts it: “Workload, lack of respect for the profession and pressure from Ofsted all contribute to a blame culture in which teachers are ‘named and shamed’. It all adds up to an extremely stressful profession.”

* Teachers Under Pressure: stress in the teaching profession by Cheryl J Travers and Cary L Cooper (Routledge, 1996).