So, this is where you end up when you burn out.
An out-of-the-way mews house, just round the corner from Harley Street. No name on the door, just a buzzer.
Clinical psychologist Dr Bill Mitchell runs a practice in this well-heeled part of London, helping the burnt-out pick up the pieces of their lives and reassemble them in a healthier way.
His office could pass for a stylish sitting room were it not for the looming presence of a black leather consulting chair. On it have reclined fried-out City lawyers, traders and entrepreneurs, from their mid-20s to late 40s.
'I see a lot of people who have drifted into a burning-out state and my job is to get them into good, healthy, resilient functioning again,' says the sharply dressed Scot.
The term 'burnout' dates from a 1974 paper, Staff Burn-Out, by US psychologist Herbert Freudenberger, who went on to use it in his 1980 book Burnout: The High Cost of High Achievement (though Graham Greene is thought to have coined the phrase for his 1961 novel about a washed-up architect, A Burnt-Out Case).
Since then, it has entered everyday language, but it is not a medically defined term.
'Burnout isn't a diagnosis,' says Dr Clare Gerada, chair of the Royal College of General Practitioners. 'It's a very American term that is used to describe people at the end of their tether.'
Exhaustion, cynicism and inefficacy are the generally agreed symptoms of this pseudo-medical term. Clinically, burnout overlaps with stress, depression and chronic fatigue.
'The physical state of burnout is when your body says it's time to stop,' says Dr Libby Hodges, a GP and life coach who helps burning-out professionals. Things go wrong gradually over months, sometimes a few years, and then they reach a critical point where suddenly it becomes much more serious.
Burnout can affect exhausted people at any stage of their career and from any walk of life, from nurse or teacher to plumber or chef. But there is one type of personality that is prone to it, and on which MT focuses here.
This is the highly ambitious, competitive, achievement-orientated and conscientious (often perfectionist) person for whom career means everything. 'Their job and who they are is one,' explains Mitchell. They are usually under huge amounts of pressure at work but also put themselves under a lot of pressure to succeed.
Mitchell, who has been working with burnout sufferers since the 1980s, has noticed a considerable rise in the number of people slowly burning out since then, though they wouldn't necessarily label themselves as such.
'Many people wouldn't see that they were rolling into burnout but they would recognise that they were stressed,' says Mitchell, who believes burnout and its attendant symptoms - feeling overwhelmed, sleep problems, struggling with day-to-day life - have been on the rise for the past 15 years.
'These conditions are much more frequent because life is much more demanding now. One of the key things is this business of work not having any boundaries. If you're really conscientious, then you are never finished, and that's an incredible burden,' says Mitchell.
Richard Jolly, adjunct professor of organisational behaviour at London Business School, agrees. He teaches senior executives about the dangers of burnout in his course on change management.
'Boundaries around work have completely exploded,' he says. 'It's like Boyle's Law in physics, where gases expand to fill the space.'
In business, Parkinson's Law explained the idea that work expands to fill the available time, 'but the problem now is that available time is 24/7.' Twenty years ago, you were kicked out the office at 7pm by the security guard who came round to switch off the lights.
Today, courtesy of smartphones, laptops and Wi-Fi, you can work from the moment you wake up to the minute you go to bed - and many high flyers do.
Add to this the uncertainty caused by the recession, the strategy of continuous change at many organisations, which means goalposts are always moving, and the demands of a young family or ageing parents just as your career ratchets up a level, and it's no wonder the pressure becomes too much.
Burnout often comes down to feeling a loss of control, argues Jolly, who cites the most stressful industries as professional services firms, such as accountants, City law firms, management consultancies and creative industries like advertising because it's the client who decides what time you leave the office each day, not you.
Then there are jobs in, say, investment banking, where a culture of competition rather than collaboration reigns.
Jolly explains: 'Banking has a "what you kill" culture, so you are competing with people to see who is going to get the biggest compensation that year. If you want to see a really miserable group of people, look at investment bankers in bonus week.'
Corporate high flyer, dotcom entrepreneur and successful consultant Chris Green* knows all about the nightmare of burnout.
Nine years ago in his early 30s, he was brought in as a junior partner by the two older partners of a successful dotcom start-up.
'They decided it was so good that they would try to get me out,' he says sarcastically. 'I'd never had people come after me at work before, and rather than run away, I had to stay because my money was locked into the business.'
This coincided with the birth of Green's third child. 'It all piled up,' he recalls.
He went to his GP with debilitating headaches, though MMI scans showed nothing physiologically wrong. The doctor recommended Green take a chunk of time off work, but he refused.
'I didn't want to show weakness,' he says. 'I didn't want to tell the partners, because it would give them a sense of victory.'
What is it like to burn out?
'The worst part was not only feeling completely bedraggled, but, instead of wanting to talk about it, all I could do was work,' Green recalls. 'It was my first major setback and it happened too late in my career. It felt as if it was partly my creation. I really defined myself by my work and I felt I had failed because I couldn't cope. But in fact it was the making of me. I'm a very firm believer that you have to see the dark side in order to know what you're capable of.'
Green comes across as someone unencumbered by self-doubt, but he admits that deep down he's an insecure overachiever. 'I'm worried about being a fraud so you seek the test that means you can prove yourself,' he confesses. 'I'm addicted to stress - it gives me focus, makes me feel important and gives my work meaning. I like dancing on the tightrope. I used to enjoy very little separation between work and life - I revelled in it. I had an office at home and my BlackBerry was always on.'
The time when you most need help, he explains, is when you are least able to extricate yourself from the situation.
'You stumble into the vortex,' he says. He found himself having moments of clarity when he knew he wasn't coping, but at the same time feeling he couldn't do anything about it. 'I knew I should escape to replenish myself, that I should go out for a drink with my friends and go to the gym - all the stuff to keep yourself in good shape - but I just wasn't able to take that way out.'
The initial burnout phase ended once he'd removed himself from the toxic environment. 'A big part of it was the feeling of being trapped, but my pride stopped me from just walking away.' Once he exited, a sense of control returned. 'I felt like the captain of my ship again.'
WARNING SIGNS OF BURNOUT
Green says it took him seven years to get over his experience of burning out, and to prove to himself that he could still be a success.
He was helped by a supportive wife and two psychologist friends, as well as a life coach, and, ultimately, he says the experience made him a stronger person. He couldn't, however, guarantee that it wouldn't happen again.
Francesca Collins* has been through two burnouts. The first was nine years ago when she was 28 and working as the PR and development manager at a crime reduction charity in London.
Having finished a client meeting at the Barbican one morning, she found herself unable to remember how to get back to her office. She told herself this was due to being very tired and assumed she would remember the route any second, but she didn't. 'It was very scary,' she says.
Her partner happened to phone and managed to tell Collins how to get back to the office, where her boss helped her. Then she went to her GP. 'The doctor didn't actually have any idea how long it would last,' she explains. 'He said my brain was like a hard drive that was under so much pressure that it had dumped the information it didn't need.'
She couldn't remember how to make coffee, whether or not she'd eaten a meal or which key unlocked her front door. The memory loss lasted a couple of weeks before she started to recover.
Before this happened, Collins had been working 14-hour days in a job that she loved. She didn't like being signed off. 'I overplayed my sense of importance,' she explains. 'I genuinely thought they wouldn't be able to continue without me. One of the hardest things with burnout is that you want the whole world to stop spinning while you catch your breath.'
After six weeks off, she went back to work gradually. Collins knew things had to change and so did her boss.
They both became stricter about what time she left work, and made sure she took time off for holidays (something she'd been sacrificing). She also learnt to leave her BlackBerry at home when she went away.
After receiving help from a psychotherapist, she has also learnt that she doesn't have to give 120% at work; that 80% would suffice. 'Good enough is good enough,' says Collins.
The second time it happened, four years later, she was working for another social enterprise, where she had been for 18 months as a development manager.
One day, she found herself walking out of a meeting saying she'd had enough. 'I was very, very unwell,' she says, and eventually self-harmed. 'I felt so frustrated and helpless and I couldn't keep on top of the anxiety.' This 'critical point', as Mitchell would term it, came about because of the build-up of an unmanageable situation.
A new chief executive kept shifting the goalposts. 'I couldn't be in control of my workload - it was always being influenced by other people,' says Collins.
Eight months later, she now works for another organisation four days a week, has recovered and is much happier. Her advice to those who burn out is that 'it's not the end of the world. It's nothing to be ashamed of and it can happen to anybody.'
Talk to people you can trust, live one moment at a time, and try to see the humanity and even humour in it.
Sometimes people just jack in their career, says Mitchell. 'Not a large proportion,' he admits.
'For most of them, I try to get them back to the work they've been doing but doing it in a different way.' The emphasis must be on their own wellbeing, he explains, which means looking after their energy levels, getting the right balance in their lives, and putting in some non-negotiable boundaries to fence off work from the rest of their lives. It also means reducing the number of hours they work so that when they are in the office, they work in a smarter way - not least, learning to delegate and to say no.
Do they feel like a failure because this has happened to them?
'No, not if this is treated properly,' says Mitchell, 'because they see this as a real opportunity for them about making some critical changes in how they lead their lives without compromising their ambitions. Many of these people carry on, get promoted and move further along in their careers. They don't need to do a U-turn. Many see later that it was one of the most productive things that has ever happened in their lives, because they see that they were locked into a way of working that was nuts.'
The cognitive side of a burnout victim must also receive attention: the perfectionism, the over-desire to please everybody, and the feeling that if anything goes wrong, it's a personal failure.
The best thing of all is to prevent burnout from happening in the first place. 'Just do not ignore balance,' warns Mitchell.
'Do not assume that your energy is an inexhaustible battery. Make some things in your life non-negotiable, like exercise or sleep, or an evening a week with your family, or keeping your weekends free,' he advises.
Also, find the confidence to switch off your smartphone, not to answer emails at the weekend, and to enjoy holidays without work interrupting.
Antonio Horta-Osorio, the chief executive of Lloyds Banking Group, no doubt understands all too well the perils of having work consume your entire life.
In 2011, he was signed off his high-pressure job, suffering from exhaustion because of sleep-deprivation. He spent eight days at the Priory just sleeping. 'With hindsight, I probably threw myself in too much,' he told the Telegraph after this return. 'Focused too much, with too much intensity and I should have dealt with it differently.'
He added: 'I will have a balanced lifestyle. This is not a matter of working hours, but priorities.'
* Names have been changed