If you saw it mapped out on paper, there would be a graph with a steady curve heading merrily upwards – that's confidence, sense of self, and so on, all the good stuff – bisected by a graph showing a steady, sad, inexorable decline to represent physical attractiveness and sexuality. The point at which the two meet is, in my opinion, 45; and where the meeting happens, there is a sudden, violent frisson.
This is the average age at which women have affairs these days, because it is the moment at which dawning recognition of time's winged chariot at our backs is still a spur rather than a crushing, crippling realisation. At 45, our physical hotness is still reasonably effortless and resilient – we don't yet need all light to be diffused through a thick piece of cream-coloured gauze, and to be carefully 'arranged' before being seen naked. We have a few good years left in us, and we know it.
We also only have a few good years left in us, and we know that, too. And, so, on the basis that this might well be our last hurrah, we leap. Obviously, it is no accident that 48 is the average age for divorce in Ireland.
And before anyone jumps down my throat about how women are beautiful and valuable at every age – let me say, duh! I know that. You might know it, too. But the rest of the western world – largely – does not. Last year, Kristin Scott Thomas, one of the most beautiful women in the world and a famous and highly respected actress, now 53, talked about becoming invisible.
"I'm not talking about in a private setting, at a dinner party or anything," she said. "But when you're walking down the street, you get bumped into, people slam doors in your face – they just don't notice you. Somehow, you just vanish. It's a cliche, but men grow in gravitas as they get older, while women just disappear."
If it can happen to her, it is going to happen to all of us. That is the winged chariot that we hear, and that is what lends such poignant urgency to all the big things that we do in our 40s.
There is a misapprehension that men are more likely to experience a midlife crisis than women – not so. But they are more likely to make a massive, big, public deal about it. Naturally. Women, as usual, just get on with it. Even if 'It' is now having unsuitable affairs, transforming their vaginas into Tiffany boxes or reconstructing the entire house using a neutral palette with touches of Radiant Orchid.
Luckily, it isn't only affairs, although these are the most visible and populist manifestation. That frisson, otherwise known as the midlife crisis, also lends itself to many positive things – charity work, triathlons, makeovers, fostering children, polar marathons, better grooming, age-appropriate dressing, forcing our spoilt teenagers to spend Christmas at the homeless shelter.
Frankly, much of the really good stuff that women do in the outside world, the world beyond their domestic sphere, happens in this decade. There is not a town or parish in the country that could function without these women. They are the mainstay of every charitable initiative there is. But these things are not done without some pain and difficulty, too.
The good news is that we have gained about five years in the last couple of decades. My mother's line was always "at 40, you either change career, have a baby, or have an affair." And, indeed, like clockwork, as she and her friends hit 40, there was a sudden smattering of new babies, careers and the odd broken marriage. "Among my contemporaries," my Brussels-based mother added, "it was the Irish women who manifested the most dramatic symptoms, and I'm not sure whether it was that Irish women were actually more feisty than their near-European counterparts – there are the ancient Brehon laws to support this – or whether an early, repressed upbringing brought them into a late, desperate grab for excitement, or the late discovery that their husbands were fools". These days, though, 40 is still young.
We mark that milestone birthday with a celebration based on relief – "Look, nothing happened! The sky didn't fall in after all. I can still fit into my skinny jeans, my boss wants to talk to me about promotion, and that guy at the bar just bought me a drink."
We lull ourselves into a feeling of security that is built, not just on shifting sands, but on outright deception. "We won't get old," we think, "that was for previous generations. It's an attitude of mind," – said in lofty tones – "and we're not falling for it." Then we wake up four, maybe five, seven, if we're lucky, years later and realise that, alas, it is us, too.
Overnight, it seems, we go from youth to middle age, just at the point where we had convinced ourselves it wouldn't happen.
But let's look at the good stuff first. "Women in their 40s feel they have less to prove. They have worked towards a level of acceptance of themselves, they are no longer running around trying to be excellent at everything; they know the one or two things they want to be excellent at," says Natasha Fennell, a director of Stillwater Communications, and founder of the very popular Art of Confidence workshops. "The women I work with, who are in their 40s, have a much better sense of who they are, they are more comfortable in their own skin. They also understand that there is no such thing as a wholly confident person – just people who have achieved a level of confidence in certain aspects of their lives.
"Knowing that is a lessening of the burden. These women know what is important to them, and that is where they concentrate their energy," says Natasha.
This rising confidence meets, usually, a point at which children are no longer tiny, so that there is, suddenly, a bit of energy to spare; careers are reasonably well-established, and earning power is good.
The frantic paddling of the 30s, where it was a battle simply to stay afloat and stay moving, recedes, and what is left is a luxurious feeling of time, energy, space.
And into that space comes good works, bad men, Botox, bangs (just ask Michelle Obama: "I couldn't get a sports car. They won't let me bungee jump. So, instead, I cut my bangs," she said shortly after her 49th birthday). Oh, and Brazilians.
Annemarie Curran, manager of Brazilia waxing salon on South William Street, Dublin, says there is a hiatus among women in their 30s coming in for bikini waxing.
"Women in their 20s come, then not that many in their 30s. They seem to be too busy, but, in their 40s, they start to come back, or come for the first time, asking for the full Brazilian, or something very close. And far from being mortified, they are highly enthusiastic." Some are doing it because they have teenage daughters, and want to see what the big deal is; others come because they have started dating again, and wish to be on terms of intimacy with the new grooming norms. Most, according to Annemarie, come for themselves. Because they want to. It's a kind of signifier – "I am not totally over the hill. I am still positioning myself as a sexual creature. I have a bit of extra time now, and I damn well choose to spend it on my bikini line."
The combination of desire, urgency and irreverence in this decade can make women magnetically attractive, particularly, it seems, to younger men. I have a friend, not married, no kids, 43, who says she walks into a bar or nightclub, scans the room, and mentally selects which of the young men she will go for, on the basis that she can have any of them. And I'm talking much younger. She sets a ceiling of around 30.
"Young men like older women," she says. "I have my own money, my own house and career, I don't want kids and I don't want a relationship. Sexually, men in their 20s are well-matched with women in their 40s."
I know that all sounds exactly like a cliche, the 'cougar' construct we all heard too much about a couple of years ago, but it actually seems to be true. However, it cuts two ways.
Another friend, recently separated and looking for romance, positively bemoans the lack of men her own age.
"The younger ones are around, and very keen for an affair, but I never meet any men my age who are interested in me. They want younger women, or they want a family, and I already have one." This is the age at which a visual gap opens between women who Do (facial peels, laser resurfacing, relentless diet or exercise, various surgical procedures, dress-right-for-their-type) and those who resolutely Don't. The gap grows steadily, so that, by the end of the decade, there can appear to be as much as 10 years between the two types, where, in reality, a matter of months might separate them.
Spectacular downsizing is another indicator – the desire for a simple life, pursued through a move to the country, the growing of organic vegetables and adherence to Eastern-style philosophies about living in the Now. It is also the decade of the mature student, where women go back to college, or go for the first time, and do degrees (in my experience) in law, art history or English literature. They don't usually practice, just acquire the extra learning for its own glorious sake.
Extreme exercise, naturally, comes into its own, as women who have done little more than walk to the shops in 25 years, suddenly take up marathon running, mountain climbing, cross-country cycling, and so on, in a heroic effort to physically hold back the march of time. "I can't be getting older, see, I can run a marathon in under four-and-a-half hours . . ." Or, like Bo Derek, swim the gruelling Hellespont waterway at Istanbul: "It was some sort of midlife crisis, for sure, probably my third," she said cheerfully last year. Best of all, if you ask me, is the unsquashable feeling so many women have of needing to leave the world a slightly better place than they found it.
Departing this life – as they suddenly realise they inevitably will – knowing that they have used their energy for good, beyond the immediate circle of friends and family, becomes a focus. This is the decade when women realise that the world is a terrible place that needs fixing, and so they start fixing. Volunteering, chairing, organising.
But, with all the good things, can come a very alarming, dark side. The highest rate of suicide for Irish women is to be found in the 45-60 age bracket. And this rate has remained constant for many years now, regardless of what is going on in the outside world. The recession has brought higher suicide rates for men; those for women in this age group have stayed the same – relatively unrecognised, unchallenged. For all that we hear of the terrible pressures on teenage girls, there's real damage being done among women facing the middle of their lives, and wondering what on earth to do.
Joan Freeman, psychologist and founder of Pieta House, which recently opened an eighth centre in Castleisland, Co Kerry, says: "There are two occasions when women are at their most vulnerable – in their teens, when their bodies, thought processes and the way the world views them, changes. And when that happens, all over again, between the age of 45 and 55. At that age, their children have usually left home, they are facing the loss of fertility, loss of attractiveness, and a huge change in the way the world views them. The menopause is physically and psychologically very difficult.
"There are a series of endings for women, often leaving a desperate void. Again and again, I hear women talking about feeling invisible." Self-harm, excessive drinking and self-medicating are also very realistic dangers, as women look for ways through their physical and psychological crises. I have known women who took to heroin in their late-40s, with truly devastating results, as well as others who were almost equally self-destructive – tearing families apart with love affairs that don't last and they often couldn't recall the point of 10 years later.
There is, though, Joan Freeman insists, a plus side. "Life can start at 50, if you view it in the right way. If you see beginnings, rather than endings: new freedoms, new focus, new sense of purpose. And," she adds, "there is definitely a dizzy period between 40 and 45, when the bad stuff hasn't happened yet, but you know it will."
And so back we come to this notion of a last hurrah, time to kick up your heels, still in possession of all your best attributes, still visible, still desirable, and with the end in sight to make it all the more urgent.
The Chinese, as we are all sick of being told, use the same word for crisis and opportunity. Or, as John F Kennedy put it: "The Chinese use two brush strokes to write the word 'crisis.' One brush stroke stands for danger; the other for opportunity. In a crisis, be aware of the danger – but recognise the opportunity."
To simply dismiss the midlife crisis as a time of too much cleavage and committee work is to miss the point entirely. Those years of extra energy, self-assurance, a certain insouciance born of an understanding of impermanence, are a giant opportunity; a potentially fabulous time full of the irresistible combination of creativity and confidence. A decade in which to take stock, re-evaluate, refocus.
As Leonard Cohen, paraphrasing Rumi, has it: "Ring the bells that still can ring/Forget your perfect offerings/There is a crack in everything/That's how the light gets in."
Or, as my mother says, most wisely, "Don't waste it."
Committed to cougar-dom long before the media came up with a name for it. Enjoying her sexual peak without apology or explanation. If she was a man, the dating age gaps would raise eyebrows. As a woman, she gets away with it. Just. Samantha Jones, played by Kim Cattrall, right, from Sex and the City, is her fictional hero, or real-life Demi Moore
We love her. Bet she's into black leather trousers and a see-through top, probably with studded wristbands and a new tattoo, channelling Goldie Hawn, above, as she was in The Banger Sisters. The life and soul of every party, rediscovers cocktails, Topshop and recreational drug use. Doesn't believe the guys who say that she and her daughter could be sisters – but dates them anyway
Is having none of it. She simply steps up the salon appointments, switches seamlessly from facial peels to Botox and fillers, and then she starts to investigate the wisdom of the full face-lift. This woman is determined to look better at 50 than she did at 30. Often succeeds. Nicole Kidman, above, as she was in The Stepford Wives, is her role model
Caught between elderly parents, seriously ill friends and continuing domestic demands, the Reluctant simply doesn't have time for a midlife crisis. Stifles it, although sometimes it hits, with a wallop, 10 years down the line. Her idol: Meryl Streep, above, as she was in The Bridges of Madison County. And It's Complicated. Actually, Meryl may be the idol of all midlife crisis women . . .
Lets it go so fast you can't help thinking she's relieved. Breaks out the elasticated trousers, loose tops and short, practical haircut with indecent haste. Soon, she's 43-going-on-60. Talks gleefully about hot flushes and menopausal memory loss. Infuriates friends by telling her age unasked, and insisting they are "all in the same boat". Thinks she's Germaine Greer, above. Isn't
Makes the world go round. Literally, in many cases. First in, last to leave; there isn't a cake sale, soup kitchen, charity shop, sponsored walk or relief effort that could succeed without her. The unsung hero of the age. Idols: Helen Mirren as she was in Calendar Girls and Susan Sarandon, left, as she was in Little Women
THE ETERNAL ENFANT TERRIBLE
Hangs out with people at least a decade older, for protective cover. She tends to reconnect with old boyfriends through Facebook and Friends Reunited, rather than meet anyone new. Her hero is Tina Brown, left, married to Harold Evans, right, 25 years her senior, who has said that she never feels old because, in his eyes, she is forever young
Sunday Indo Life Magazine