Arguably the cruellest thing you can do to human beings is to rob them of faith in their own sanity. People can endure physical torment, even torture, so long as their minds are clear. If they feel sane, they can still make sense of what is happening to them and work out how to survive. But if you undermine somebody’s mental stability, they soon unravel. In the words of John Milton’s Satan in Paradise Lost, ‘Which way I fly is hell; myself am hell;/And in the lowest deep a lower deep,/Still threatening to devour me, opens wide.’

Chipping away at a person’s mental health is known as ‘gaslighting’, after Gas Light, the Patrick Hamilton play that in 1944 became a classic Hollywood melodrama. In the film, Paula, played by Ingrid Bergman, has a husband called Gregory (Charles Boyer) who wants her ‘sent to the madhouse’ so he can get his hands on some family jewels. He accuses Paula of forgetting, losing and stealing things. He tells her she is too unwell to see visitors or go out. He gets into their attic from another building and when she sees the gas lamps dim and hears footsteps upstairs, he tells her she is deluded. His voice quietly unmoors her sanity: ‘I hope you’re not starting to imagine things again. It hurts me when you’re ill and fanciful.’ As Paula is about to be certified, rescue comes in the shape of detective Brian Cameron (Joseph Cotten), who sees the gas jets go down and tells her: ‘You’re not going out of your mind. You’re slowly and systematically being driven out of your mind.’

This angst-ridden age is full of gaslighting. Generation Y spend their time writhing in anxiety, with which they infect their friends on social media. Elderly people whose relatives want rid of them are pushed them towards a diagnosis of dementia (for which their GPs, until recently, got a £55 incentive). There are the victims of domestic abuse, told repeatedly that they’re mad until they are (like Paula, and like Helen in The Archers by her undermining husband Rob). Then there are the great masses of the ‘stressed’, told by society to think of themselves as dangerously ill. Emotions such as fear, nervousness, anger, frustration and worry used to be accepted as normal, however unpleasant. Now they are being pathologised by pseudoscience that uses the control term ‘stress’ for stimulus, response, interaction and transaction. In the clinical literature it can embrace the entire emotional spectrum, which is not only bogus but also deeply unsettling.

Gaslighting in wartime is a punishable offence (‘spreading alarm and despondency’) because left unchecked it destroys morale. Churchill’s great rallying speeches strengthened Britain’s sanity as well as our resolve. What has happened to his ‘lion-hearted nation’, the progeny of those who survived wars and workhouses? The answer, arguably, is that we have been destabilised by drip-fed suggestions that we are psychologically unwell and cannot cope. An unregulated multimillion-pound industry marketing calm-down therapies on 15 million websites spreads ‘stress awareness’. People reacting to real problems, instead of being given practical help and advice, are offered nostrums, symptom lists, potted endochrinology, the chemical cosh.

My work, which recommends traditional problem-solving skills and robustness training rather than soothing and drugs, has led to accusations that I am ‘a heartless bitch’. But my books present evidence that ‘stress management’ has not just failed to halt spiralling mental health casualties and work absenteeism; it has itself helped to create the pandemic. Despite the Health and Safety Executive’s new ‘stress’ standards and costly initiatives, the number of cases of work-related stress, depression or anxiety in 2014/15 was unimproved at 440,000, with 234,000 new cases.

‘Stress’ medication, for the young and anxious, for the jaded at work, for the elderly, costs the NHS a fortune. It also costs lives. Professor Heather Ashton of Newcastle University, extrapolating from Home Office records between 1964 and 2004, found 17,000 deaths linked to benzodiazepines. Yet millions of patients still receive ‘benzos’ and many become hopelessly addicted. Prescriptions for antidepressants have doubled over the past decade. The drug manufacturers are well aware of a dangerous side effect, akathisia or violent mental agitation. The website AntiDepAware, run by a man whose son committed suicide days after being prescribed Citalopram, examines hundreds of coroners’ reports and cases of suicide and homicide by patients whose antidepressant dosage was new, curtailed or interrupted.

The sociologist David Wainwright, a senior lecturer in the health department at Bath University, is an opponent of playground ‘stress awareness’ and ‘safe spaces’ on campuses: ‘Over the past 40 years there has been an inversion of traditional values of courage, resilience and stoicism,’ he says. ‘A “stiff upper lip” is increasingly seen as a problem and encouraging people to confront their fears is viewed as grossly insensitive or damaging. The outcome is an amplified sense of emotional vulnerability and the widespread belief that the challenges and problems of everyday life cannot be managed without professional intervention.’

If we could only bring him back, Dr William Johnson, a hero of the Somme, would be the physician we need to reverse the gaslighting. Johnson was later put in charge of No. 62 Casualty Clearing Station behind the line at Passchendaele. He felt that the climate of belief in the newly coined ‘shellshock’ had convinced the troops that it was a ‘definite disease and that the term meant some mysterious change in the nervous system’. Johnson felt that such beliefs inspired terror and a variety of scary but unnecessary physical conditions in soldiers under fire.

Many thousands of men passed through Johnson’s tent at a rate of 60 a day, and the doctor provided what he called ‘an atmosphere of cure’. The practical strategies he prescribed, such as massage, blowing into a paper bag and phonating words, were far less important than that the patient should trust his judgement that the symptoms were a normal reaction and not the sign of incipient madness. Each soldier was respected as compos mentis, exhausted and in need of rest, after which he would be fighting fit again.