It was like a mist coming down — a dark mist that clung to every part of my body and mind. I lived it and breathed it. It shrouded me in a deep anguish that gnawed within. I felt lonely, forlorn, lost, helpless. I was being sucked under this dark, thick, disgusting quagmire.

Every thought condemned me.

I felt my depression was a moral defect: I was a weak person, I shouldn’t have let this happen, I was ruining my own life and ruining life for everybody around me. I felt my husband Phil deserved a better wife, and that if I was out of the way he could remarry. I had to die.

I thought I knew about mental illness. After all, I am a doctor — a specialist registrar in emergency medicine. But all my training and knowledge could not prepare me for the seven years I lost to worthlessness and the all-consuming urge to harm myself.

There doesn’t have to be a reason why people get depressed or suicidal. It can come from nowhere and plunge perfectly normal people into a pit where it seems the only escape is death. That is what happened to me.

My story is necessarily harrowing, with disturbing glimpses of how the NHS deals with an often hidden and stigmatised disease. But ultimately it is also about redemption. Thanks to pioneering treatment in a Scottish hospital I am living proof that mental illness can be cured, just like any other disease. This is a story with a happy ending.

It was December 1994 when I felt the depression descend. I was a busy mother of four, a doctor in an accident and emergency department in Southampton. My children — Rebecca, 12, Simon, 10, Stephanie, 8 and Jonathan, 6 — were healthy and happy, the girls showing potential to be top-class ballet dancers.

Hours as a junior doctor were long and the work was sometimes difficult, but I had made the decision to go part-time and Phil and I were pleased with how the future looked.

Yet I was continuously exhausted, and sleep, when it came, would never refresh me. Every task, however small, was an effort. Eating was a chore. I diagnosed myself — I knew I was depressed. And I knew that people who were depressed got treatment and got better very quickly. So I thought, anyway. I started on medication and took some time off work. Surely that would do the trick? The depression deepened. I would spend days in the bedroom, refusing to come out or to speak. One day I phoned one of my friends who happened to be a psychiatrist and told her: “I’m going to kill myself.” It was a gradual realisation I’d come to, amid an overwhelming sense of despair and anguish.

My doctor said if I had electroconvulsive therapy (ECT), I would feel better. I remember the bewilderment I felt when Phil left me at the hospital. I was thinking: “What on earth have I done?” I was entering the world of the mentally ill where there are no flowers, no chocolates and no sympathy.

In the coming years I would have ECT more than 100 times, usually with helpful — but temporary — effects. ECT is not at all like it is portrayed on television. You are given an anaesthetic, then you are given an electric shock which causes your body to have a fit. They give you paralysing agent so your body doesn’t jerk around like you see in films.

But things can go wrong. Once, the anaesthetist made the mistake of giving me the paralysing drug before putting me to sleep. I was left paralysed, unable to move or communicate, knowing what was about to happen. In my mind I was shouting at them: “I’m awake, I’m awake, don’t do it! Please don’t do it!” The first jolt knocked me out.

After my first six weeks in hospital I was allowed home, but soon all I could think about was ways I could end my life. It became a pattern where I would be admitted and given ECT and that would just lift my mood enough for me to go home. But the desire to harm myself was becoming worse.

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