Rare is the practising doctor who speaks openly about having had a serious mental-health problem. Rarer still is the doctor who, dismissed by colleagues as unfit for work, devises her own self-help technique to escape the dark shadows of her mind. But that’s exactly what Dr Liz Miller, a 52-year-old Fulham-based GP and occupational-health specialist, has done. Mood mapping — her invention for plotting moods on a chart and making changes based on the patterns — cured her bipolar disorder, she says, and can transform the life of anyone struggling with negative moods.

At 28, Miller was one of the brightest young stars in British neuroscience. Paying no heed to the stress and exhaustion that came with the job, she immersed herself in her work, regularly speaking at international conferences and spending long hours ­doing research. Then, seemingly out of the blue, bipolar disorder struck. “I became stressed, anxious and hyper, and didn’t turn up for work because I was manic,” Miller recalls. “I spent my time at home doing nothing or riding buses talking to people.” She soon found herself sectioned in the locked ward of the Edinburgh Royal Infirmary.

It took Miller 10 months to recover from this breakdown, which she now believes was triggered by the stressful and isolating nature of her career, a career that she now found in ruins. “I had no references, nothing. The attitude of doctors was simply, ‘You’ve had a mental-health problem, therefore you shouldn’t work as a doctor.’”

Over the next decade, Miller’s life went downhill. Through favours from personal contacts, she found work in A&E and covered up what had happened, telling nobody. But the illness came back and she was hospitalised again. Doctors, she says, treated her with contempt: she was no longer one of them. Not being able to work was a turning point. “I was 40 and terrified of getting ill again,” she says. “I was prepared to do ­absolutely anything to find out what had happened to my mind. I was taking medication, but didn’t want to be dependent on it.” She started reading everything she could about bipolar disorder — and drew a blank. “Nobody knew what the problem was, apart from a ‘mood disorder’,” she says.

Wondering what mood “order” might be instead, she did a psychology degree and started tracking her moods, a cognitive technique that psychologists use. “I started writing a diary, and charting, on a scale of one to 10, how I was feeling, what I’d eaten, how much money I’d spent, how many cigarettes I’d smoked — just about everything — looking for clues so I didn’t have to be ill again.”

Mood mapping came out of this obsessive introspection. “I realised you could plot energy and wellbeing as two axes and put four basic moods on a map.” The simple 'up and down' mood charts used for decades, Miller believes, don’t define your mood sufficiently – mood mapping moves this on by separating out anxiety from depression, and different highs of ‘active’ and ‘calm’.

She developed a chart and started plotting her own moods several times a day. From this, she could make changes to ­stabilise how she felt. Health was one of her main mood triggers, so she gave up junk food, started exercising in the open air and stopped smoking. Now, after mood mapping for a decade, she has been ­medication-free for eight years.

When Miller shared her technique with firefighters, it worked for them, too, which led to the realisation that mood mapping could also treat anxiety, work stress, physical pain and everyday life with all its worries. Now Miller has a new book out and, in recognition of her work, she was voted mental-health charity Mind champion of the year in 2008. “I’ve never been happier, healthier, stronger and fitter,” she says. “As far as I’m concerned, I’m cured.”

Mood Mapping by Dr Liz Miller is out now (Rodale £12.99)