In 2002, Allison Pearson emerged as the chief chronicler of a very modern female malady: the crazed pursuit of the perfect life. Her novel, I Don't Know How She Does It, which started life as a column in the Daily Telegraph, told the story of that rarely sighted beast, a female hedge fund manager, and followed her struggle to juggle two children with her very full-time job. The protagonist, Kate Reddy, may have had a nanny and a husband who was both gainfully employed and nifty in the kitchen, but her life seemed full of comic anxieties. (The novel opened with her attempts to "distress" some Sainsbury's mince pies that her daughter was taking to school, so that they looked appropriately, maternally, handmade.) And while the book depicted an aspirational bubble that floats way over most of our heads, it found an immediate audience. In fact, it became a bestseller, the film rights were sold, and Oprah Winfrey – that essential filter of the modern female experience – described it as a "bible for the working mother".

In her worldly success, and her approach to life, it was assumed that Pearson was very similar to her protagonist. She's a high-flying journalist who has won a number of awards; her partner is New Yorker writer Anthony Lane; she has two children. In precis, it's a convincing portrait of a perfect life. But yesterday, her comic tone was jettisoned. Pearson has been writing for the Daily Mail for some years now, but this column was to be her last, she said, because she has depression. She had always wanted to be "the best kind of girl", but recently she found herself in a psychiatrist's consulting room, assessing just how unhappy she was. The psychiatrist asked if she'd had any suicidal thoughts, and "I didn't mention the strange allure of a nearby motorway bridge at dead of night . . . Eventually, I blurted into the silence: 'Sometimes, I think it would be easier not to be. Not to be dead. I have two children, I can't leave them. But just to stop, you know. To not exist for a while.'"

Pearson went on to describe herself as a "sandwich woman", one of a generation who had waited until their 30s to have children and then, just as their offspring were "sleeping through the night, one of [their] parents fell ill". The stress of this situation – and a job on top – has taken its toll. "Is it women who are mad, or is it the society we live in?" she asked. "We always suspected there would be a price for Having it All, and we were happy to pay it; but we didn't know the cost would be to our mental health."

Over the last few months, many other stories like Pearson's have emerged – tales of apparently enviable lives laid low. In January, the popular novelist Marian Keyes posted a message on her website attesting to her "crippling depression . . . I can't eat, I can't sleep, I can't write, I can't read, I can't talk to people". In February, an inquest found that the bestselling author Susan Morgan – who wrote under the pen name Zoe Barnes – had killed herself. In March, on Desert Island Discs, the actor Emma Thompson recalled the depression she had experienced after her divorce from Kenneth Branagh in the mid-1990s, saying that she didn't think she had stayed "sane. I should have sought professional help." And over the last few years, a number of memoirs of depression have been written by women. The former Elle and Red magazine editor, Sally Brampton, wrote Shoot the Damn Dog. The former Scotland editor of the Observer, Lorna Martin, wrote Woman on the Verge of a Nervous Breakdown. And the former deputy literary editor of the Observer, Stephanie Merritt, published The Devil Within. The mood of these memoirs was captured in a long, unflinching article by the American writer Daphne Merkin in the New York Times, in which she described her depression as "the sadness that runs under the skin of things, like blood, beginning as a trickle and ending up as a haemorrhage, staining everything".

This deluge shouldn't come as a surprise; over a period of decades, study after study has suggested that women are diagnosed with depression at twice the rate of men; in recent years, one study found this specific ratio occurring across nine different countries, regardless of economics and culture. As Merritt, who has written widely on the subject, points out, these findings are open to question – "because it's possible that, for men, drug and alcohol abuse could be symptoms of a depression that they just can't articulate. It could be that women are more able to ask for help." But there is no doubt that the numbers regarding women and depression are stark – 11.2% of the female population are experiencing it at any one time.

And those figures are on the rise. Last year, an NHS study showed that between 1993 and 2007, while there had been no change in the number of common mental disorders such as depression and panic attacks in men, they had risen by a fifth for women aged 45-64. For over-75s, such disorders were twice as likely among women as men. A study of 15-year-olds in Scotland found that while 19% of girls experienced such common mental disorders in 1987, that incidence had increased to 44% by 2006 (a year in which the figure for boys reached 21%). And, last year, in the US, academics Betsey Stevenson and Justin Wolfers published a report called The Paradox of Declining Female Happiness. "The lives of women in the US have improved over the past 35 years by many objective measures," they wrote, "yet we show that measures of subjective wellbeing indicate that women's happiness has declined both absolutely and relative to men."

Of course, when studies of this kind are published – spanning the period of second-wave feminism, and showing a diminution in female happiness – the word often goes out that it is time for women to throw off their business suits and get back in the kitchen. The argument runs that feminism has failed, worn women out, and that a return to domesticity is the answer. The problem is, of course, that the domestic realm was itself a depressant – as anyone who has ever read The Yellow Wallpaper or The Feminine Mystique, watched The Stepford Wives, or lived through the 1950s, will fully realise.

Depression can, of course, have a multitude of sources – divorces, bereavements, the sea-deep pain of some childhood trauma. But those problems have always existed. I ask psychologist and author Dorothy Rowe, a leading expert on depression, where she thinks this modern stream stems from. Could it have a physical basis? Could it be that old culprit: hormones? "No, there's no evidence for that at all," she says. "I remember back in the 1980s, when I was working in Lincoln, and the received wisdom was that women got depressed after childbirth because of their hormones. It's always your hormones. But at that time, under Thatcher, there was a huge recession, and there were many men who had lost their jobs at the steelworks. Their wives could work as secretaries or in shops, and the men stayed at home with small children. You suddenly found that there was an awful lot of postnatal depression among men. That's it. It's being at home, bringing up small children, and nobody ever addressing you as yourself."

Now, says Rowe, while women are still often seen as mothers rather than individuals, there are many more pressures at play. "There's still this idea that you've got to be a wonderful mother, but you also have to have a brilliant career, and you've got to look attractive all the time," she says. "There is no way that you can maintain that and bring up children. But it's still being presented to women all the time, in every magazine, on every screen, that you should."

Martin agrees with Rowe. In her mid-30s, she was diagnosed with clinical depression, started a course of antidepressants, and eventually began a long period of therapy that brought her out of the "swamplands of the soul". She feels that: "There's massive pressure on women these days to hold down a good, rewarding, fulfilling job, but also to be a good mother, and then to look good, and to look after yourself. I think there comes a point where your body can't take it." She also suspects that we are being made sicker as a result of our culture of entitlement. Consumer culture constantly undermines the idea that sadness can be an acceptable part of our lives – instead we are taught that the perfect life is verdantly happy, and that any malady can be treated, at a cost.

"I think we're conditioned to think that sadness shouldn't be part of the human condition," says Martin. "But it is. It's like all of these difficult emotions, like loss, fear of mortality. All of these emotions that seem so difficult, so they're just pushed away – then they bubble up. Perhaps we have to become a bit better at understanding and dealing with them." She admits though, that while "it's very easy for me to sit here now and say these things, four years ago, if someone had said that I should have just come to terms with my sadness, I would have wanted to kill them."

The fact is that modern women are, as Margaret Drabble has termed us, "pioneers"; while our lives have changed inestimably over the last three decades, men's have lagged behind. We have forged careers, inched ever closer to the glass ceiling, seen our salaries increase – at the same time, we're still expected to take on the lion's share of the housework and childcare. Meanwhile consumerism has dictated that we should be forever groomed, well-dressed; that in order to have a good life we need Louboutin heels and Vuitton bags, a Botoxed brow, inch-long lashes, Cath Kidston curtains and a pastel-blue Aga. It's a situation that Pearson chronicled expertly in her novel. "Is it coincidence," she wrote, "that we spend far more than our parents ever did on the restyling and improvement of our homes – homes in which we spend less and less time." And, crucially, she noted that "mysteriously, childcare, though paid for by both parents, is always deemed to be the female's responsibility."

One of the most insidious aspects of this culture is that the quest for perfection seems to stop women getting help for depression as soon as they should. As Martin says, "I desperately hated the fact that I needed help. Our culture absolutely insists on us being strong, independent women, and so the idea that you actually need a bit of help, that's the biggest hurdle." Merritt agrees: "I was very reluctant to be an object of pity, or to look vulnerable. I didn't want people to think that I couldn't manage. But the problem is that the longer you leave it, the harder it becomes, and then you just start cutting corners to keep up this appearance of competence, and eventually you just implode, or explode, because you can't keep that up indefinitely. The strain of acting the part of somebody who is doing well – and then having other people who depend on you, asking you to do more and more, is a huge issue. But I think a lot of women impose that on themselves."

One obvious answer to all this is that men need to do more in the home. Another answer, says Rowe, is something that's easier said than done for many women. You have to let things slide. "Most girls are still brought up to be very good," she says, "and a good person is somebody who always feels that they can do better. We're brought up on the principle that if a job's worth doing, it's worth doing well. And actually, what women need to learn is that if a job's worth doing, it's worth doing badly – as long as you get it done. If you look around at the people who seem to cope with all that they've got to do, you'll see how women skimp things – saying, 'We'll have something out of the freezer tonight for dinner' for instance. You need to distinguish very clearly between what's essential to do properly, and what isn't essential. There's a lot of stuff that doesn't need doing."

Like distressing your mince pies, for example.