Lynne Clayton is a manic-depressive. Her illness is characterised by extreme highs (mania) and lows (depression), which makes holding down a full-time job extremely difficult; indeed, figures from the mental health charity, Mind, reveal that 90 per cent of people diagnosed with a serious mental illness are unemployed. But 53-year-old Ms Clayton is, or rather was, one of the lucky few. Despite her debilitating condition, she clocked up an astonishing 31 years as a secondary school teacher before retiring two years ago. Although she is no longer a teacher, a combination of peer support, medication, strength of mind, love of her job and ingenious self-management has kept her active.

Like many manic-depressives, Ms Clayton - who retired two years ago as head of English at St Saviour’s and St Olaves in the London borough of Southwark - is by nature energetic, creative and motivated. While psychiatrists might say that her extreme levels of energy are a sign of latent pathological mania, she calls it her “creative energy”.

She has always channelled it into her work, as she did when St Saviour’s embarked on a government-funded literacy drive. Ms Clayton returned home on a Friday afternoon and devoted the whole weekend, without sleeping, to producing an innovative spelling aid. By Monday afternoon it had been photocopied and was ready to be used in class. “It was this marvellous creative energy I used to work and keep going. It was also an energy I used to help keep my staff motivated,” she says.

On the occasions when her mania became uncontrollable and was in danger of compromising her professional role, she would admit herself to a psychiatric hospital. “With help and some insight I almost always was able to take appropriate action,” she says.

Ms Clayton is lucky that during her career she was well served by understanding colleagues. Although in her early years she hid her diagnosis from other teachers, she was open from the start at St Saviour’s. “When I went to see the head for an interview, I told her about my diagnosis. She was absolutely fascinated and said she did not mind at all.”

Neither did her St Saviour’s colleagues use the manic-depression label to ridicule Ms Clayton’s ideas. “We used to talk about my manic depression and my department knew about it. In fact, when we were interviewing for new members of staff, we discussed whether they should know beforehand that their head of department was manic-depressive. In the end we told them after they got the job.”

Throughout her life, Ms Clayton has developed strategies for controlling her mania which she believes have sometimes helped keep her out of hospital. Karate, in which she is a blackbelt, has been the most beneficial.

People experiencing a manic episode often suffer from “a flight of ideas”, which is when a patient will talk rapidly, switching from one subject to another, making little or no sense to the listener. Lynne Clayton uses karate’s disciplined breathing techniques to reduce the severity of these attacks. “This flight of speech, which is a type of panic, is controllable,” she explains. “As soon as you use the breathing techniques your body starts relaxing, and you can allow the ideas and words to just pass through you and flow away at their own accord.”

She has also become acutely aware of each and every emotion. “I can emotionally observe myself. Like a leper who has to check their body, I check my emotions. I have to answer why I feel like I do. If there is a reason for an emotion, then fine. If not then that is a warning sign to me. It is a way of stopping an emotion having control over you.”

Yet, as other manic-depressives confirm, mania feels so intense, many desire to re-experience it. “Although I believe I can stop a manic episode, I often do not want to because it is too important to me,” says Ms Clayton. “It may be fraught with danger, but there is an attraction to it. It’s like being a racing car driver. And if somone came along with a cure for manic depression tomorrow, I would not be interested in it because the mania is part of me. It has given me a creative personality.”

At the opposite end of the illness’s spectrum are the bouts of depression which, while terrible, have only rarely caused her to go off sick. In fact, she believes teaching has helped her crawl out of the black hole.

“When becoming depressed, it is important to keep going as normal for as long as you can. If you succumb to depression you can stay there forever. I always used to manage to drag myself out of bed and get to school. And then the kids’ enthusiasm was so powerful it would help lift me.”

But in her last five years of teaching, she suffered increasing periods of mania. She suffered one particular bout while St Saviour’s was preparing for an Ofsted inspection, which made her reconsider whether she should continue with teaching. Like everyone, Ms Clayton felt the strain of the final Ofsted preparations - but in her case the pressure took a heavy toil.

“By the time inspectors arrived on a Monday, I had not slept since the previous Thursday. I had spent the whole weekend working on two important documents. I was not eating and that, combined with the stress, meant I became delusional and was hallucinating. I had absolutely lost it.”

While her husband usually acted as her safety net by alerting her that the mania was out of control, this time she deceived him. “I pretended to go to sleep, and then as soon as my husband went to sleep I would get up and continue working,” she remembers.

During the following school week, able to disguise her mania to other people, she slept for just four hours - but not before her department had sailed through its inspection. “I remember the inspector telling me how wonderful the department was. But during the rest of the afternoon I just cried and cried. I told the head that I needed to go home. When I arrived home I just cried all weekend. I was in a terrible state.

“From then on I was up and down like a yo-yo, and I was not taking my tablets. When I went to see my consultant he said to me ‘enough is enough’.” Reluctantly, Ms Clayton agreed and took early retirement.

But she has not lost her energy and enthusiasm and has since become committed to the mental health movement. She is appalled by what she sees as threats to patients’ civil liberties by government plans for community treatment orders (CTOs), whereby patients can be compulsorily medicated in their own homes. She has also become co-chair of Southwark Mind and is involved in a campaign to create women-only wards in psychiatric hospitals.

“My time as a teacher meant I have become very good at negotiating with people. It’s a skill I use now.” Reflecting on her experience, Lynne Clayton encourages teachers to be not only tolerant of those with a mental illness, but to help counteract the negative press psychiatric patients often receive.

“I would ask teachers not to be afraid of mental illness, but to support people in a practical, kindly and empathetic way. I would also encourage them to do their best in the classroom to stop stigma and ignorance.”

For further information contact the ManicDepression Fellowship on 020 77932600.E-mail: mdf@mdf.org.uk. Mind: www.mind.org.uk

Manic depression: the facts

* Men and women of any age from adolescence onwards suffer from manic depression. It is often triggered by work, study, family or emotional pressures. In women, it can also follow childbirth or the menopause.

* Mania symptoms include rapid or incoherent thinking, paranoia and hallucinations. Depression, including overbearing feelings of emptiness and worthlessness, often follow an episode of mania.

* The causes of manic depression are highly debated. Some research suggests there may be a genetic component. Stressful events often play a part.

* Mood-stabilising medications, of which lithium is the most common, are used to treat manic-depression. “Talking therapies”, such as cognitive therapy and counselling, are also useful. Self-management techniques can also help control mania.