You could be forgiven for expecting a midlife crisis not to hit until, well, the middle of your life. But if the latest research is to be trusted, we're experiencing them earlier and earlier.
A new survey by the British counselling service Relate, The Way We Are Now, suggests that people in their late 30s and early 40s are among the unhappiest in society: lonely, dislocated, worried about money, and weighed down by the twin burdens of work and family. According to the report, 22 per cent of those surveyed have suffered depression because of a bad relationship; 23 per cent feel they don't have enough time to see their friends and 28 per cent have left a job because of a bad relationship with a colleague.
"Your 30s are when life gets really hard," says Claire Tyler, CEO of Relate. "You're starting a family, pressure at work can be immense and, increasingly, money worries can be crippling. We cannot afford to sit back and watch this happen. The ensuing effects of relationship breakdown on society are huge."
Is any of this a surprise? Not really. Our lives are radically different from those of previous generations. Our parents worked hard, for sure, and with fewer labour-saving devices. But they weren't still up at midnight answering work e-mails on their iPhones. (And in all probability, the mother stayed at home.)
Fear of redundancy wasn't as all-pervasive as it is today, and there certainly wasn't a crowd of bright-eyed interns clamouring to do your job for free. Our parents may have had money worries, but they weren't trying to make ends meet during the worst recession in living memory.
Parenting is also harder these days. The laissez-faire approach that worked so well in the 1970s and 1980s apparently is no longer sufficient in a world where competition for places at decent schools and universities is stiffer than ever. There are violin and Mandarin lessons to ferry your children to, and private tutors to hire. Homework must be overseen, lest little Johnny wastes the evening playing Medal of Honour when he should be getting to grips with quadratic equations. But this is easier said than done when you're never at home to play The Enforcer.
Life is stressful, then, for those aged between 35 and 44 - the group the Relate survey focused on. But isn't it a bit over the top to compare this stress to a midlife crisis?
Although it's much mocked and can manifest itself in a variety of different ways, the midlife crisis is at root quite a specific phenomenon: a panic response to the sudden, unpalatable realisation that you're getting old and not going to be here forever.
It's true that your 30s are when you start to notice yourself ageing - the weight that won't fall off the way it once did; the blotchy, saggy skin; the yellow teeth and receding gums. But do they really constitute "midlife", that period of transition and stock-taking from which many emerge totally different people?
Dante, in the opening stanzas of The Divine Comedy, called midlife "a dark wood where the straight way was lost". Freud had a great word for it: Torschlusspanik - the "panic before the closing of the gates". Freud's disciple-turned-rival Carl Jung was fascinated by "the moment of greatest unfolding" after which "the second half of life begins". "Passion now changes her face and is called duty," he wrote. "I want becomes the inexorable I must and the turnings of the pathway that once brought surprise and discovery become dulled by custom."
Jung believed that the first half of life should be about making your mark on the world - earning money, achieving professional status, etc. The second half, however, should represent a contraction; a chance to explore your inner self and work out who you really are.
Which sounds great in theory. But in practice this self-exploration can be painful, and not just for the person doing the exploring: there are repercussions for wives, husbands, children and friends. How could there not be, when the past suddenly seems a humiliating reminder of risks not taken and opportunities ignored? You feel restless, old, out of touch. Your cholesterol is too high and your joints ache. You can't sleep. You no longer know how to communicate with your children. New technology baffles you. You know you should do more exercise, but just can't summon the energy.
I think very few 35- to 44-year-olds feel as bad as this. In other words, mid-30s malaise is subtly different from actual midlife crisis, even though it shares some of the same symptoms. (I think mid-30s malaise is mostly about tiredness.)
What's undeniable, though, is the way thirtysomethings are being pushed into feeling older than they are by a culture that privileges youth to the point of absurdity. This mid-30s generation has always prided itself on its ability to keep up with trends. But the post-pop charts, post-iTunes atomisation of the music scene combined with the rapid evolution of new technology makes this increasingly difficult.
It's common to feel more at sea than you expect, even somewhere as innocuous as a cinema. "What was that?" my wife asked me the last time we went, having sat bewildered through a nerve-shredding collision of light and noise masquerading as an advert. "Was it trying to sell me a car?"
How can you avert this sad destiny? It's simple, really. Re-examine your goals and values before the Big Depression hits, so you won't be caught off-guard. Respect your body a bit more. In terms of your appearance, be realistic about what you can and can't change. (Men: don't dye your hair. Two words: Paul McCartney.)
Remember that happiness is necessarily fleeting: don't expect to feel jubilant all the time. And perhaps most importantly, don't become a Luddite. It's one thing to recognise that Facebook and Twitter are what the novelist Jennifer Egan has called "huge Soviet apartment blocks we've all been forced to live in"; quite another to reject the concept of social networking entirely.
Try to see the modern world as an energising challenge rather than an exhausting treadmill, and you never know - you might even convince yourself that that's what it is.
Ÿ John O'Connell is the co-author of The Midlife Manual (Short Books).