Over a lifetime, health services estimate that one in four of us is likely to suffer from a mental health disorder, an umbrella term covering everything from depression through phobias to schizophrenia. Last year, 43million SSRI prescriptions were written in England and Wales, a 28 per cent rise in three years and costing the NHS around £235million a year. Close to seven million were issued for benzodiazepines - anti-anxiety drugs including Valium and Xanax, the current pill du jour - which Vogue editor Alexandra Shulman admits to carrying in her handbag, like a "lucky charm." So what's going on? Are we really in the midst of an epidemic of depression and anxiety in this country? And if we are so depressed, what is causing it? Mental health charities have linked the rise in "mood disorders" to the recession. The psychiatrist Dr Paul Keedwell, author of How Sadness Survived, believes it's part of a bigger crisis: "We live in a capitalist, urbanised society that's all about segregation and lacking support networks, when we are social mammals wired to be in a much more close-knit community. Modern urbanism has its advantages, in that we are physically healthier, but the trade-off seems to be much more psychological disturbance. But not all health professionals agree. "Severe mood disorders used to be rare," says David Healy, professor of psychological medicine at Cardiff University. "But then the pharmaceutical companies developed SSRIs and started quoting famous episodes of depression throughout history, like Churchill and his 'Black Dog," to make out depressions like these had been around forever, and were awfully common but hadn't been picked up on. I'm sure some severe cases, like Churchill's, were missed before the invention of Prozac, but statistically depression is 10,000 times more common now than in Churchill's day. According to Healy, and many of his colleagues, our depression epidemic has been born not from public need, but from drug companies creating and then brilliantly marketing a product. "Chemicals that used to be regarded as poisons are now being used like fertilisers," he says. Yet, prevalent as they have become, antidepressants actually came about by accident, as a by-product of the search for a tuberculosis cure. In 1952, scientists discovered - quite serendipitously - that sick people given the anti-infection drugs they were developing became much more cheerful. Initially, no one knew how the drugs worked - simply that they blunted disturbing mental symptoms. Since, at the time, mental illnesses were usually tackled through partial lobotomies or the electroshock treatment recorded by Sylvia Plath in The Bell Jar, or through injections into the brain of diluted poisons like turpentine, a tidy cure-by-pill was an enormously appealing prospect. Over the next three decades, the drugs were refined as researchers investigated their effect on the levels of certain brain chemicals. Since unhappy people seemed to function better when the level of serotonin was boosted, it was extrapolated that unhappiness must derive from a lack of this chemical in the first place. In fact, this theory has never been proven. But it was on its back that Prozac was launched 24 years ago, quickly becoming the most-prescribed drug of all time and heralding a shift away from talking cures such as psychotherapy. Hotly contested also is the DSM-IV, the official diagnosis criteria for depression. This excludes patients suffering a bereavement, who are regarded as understandably low, but makes no acknowledgement of experiences such as divorce, redundancy, or a house move that could leave people stressed, but not suffering from a pathological condition that they none the less can end up being diagnosed with. Ever since Prozac's invention, debate has also raged over the chemical trials of such SSRIs. Only "positive" results were published, medical professionals argued, while negative ones languished unseen. Earlier this month, the controversies surrounding the promotion and sale of SSRIs took a dramatic new twist, when the British pharmaceutical giant GlaxoSmithKline pleaded guilty to using illegal kickbacks such as foreign holidays and concert tickets in a bid to persuade American doctors to prescribe the antidepressant Paxil to patients under 18. The drug is only approved for adult usage. It also admitted pushing the SSRI Wellbutrin for non-approved uses such as weight loss and sexual dysfunction. In Britain, meanwhile, doctors have been told to lower the maxium dose of the UK's most widely prescribed antidepressant, Cipramil, after a study last month revealed that the drugs increase the risk of heart problems which can cause sudden death. Contentious or not, many experts believe that for some severely depressed people, SSRIs can literally be life-saving. But for others, they can cause more harm than good. "Antidepressants may help you dot the i's and cross the t's but they are going to numb you emotionally and this isn't going to help you to be in tune with your kids or your wife," says Healy, who occasionally prescribes the drugs, but believes they are only needed in rare cases. From a physical point of view, the majority of SSRI users have reported a fairly major change in their ability to make love and this isn't going to help keep your marriage together. Side effects aside, chemical SSRIs are far from the wonder drugs many of us take them to be. Recent research led by Professor Irving Kirsch of Hull University, based on an aggregate of 38 clinical trials involving more than 3,000 depressed patients, and submitted to the US Food and Drug Administration, showed that SSRIs only had the same effect as a placebo on those with mild depression. Even severe depressives show only a 37 per cent improvement although this improves to 67 per cent after two different drugs are tried. Even when the correct drugs are prescribed, the risk of recurrence rises sharply when a patient comes off them, meaning many patients are destined to stay medicated indefinitely. "We are probably both over-prescribing antidepressants to people who don't need them, and at the same time we need to do a lot more work to improve antidepressants for the many people who desperately need them, but who right now are receiving inadequate treatment," Dr Keedwell tells me. Studies of natural remedies show them to have similar levels of efficacy, while their side effects can be alarming. St John's wort can - among other things - interfere with prescription drugs, like the Pill, and is banned from over-the-counter sales in Ireland. The literature accompanying the newly fashionable 5-HTP, a derivative of an African vegetable seed, Griffonia simplicifolia, warns that it can produce nausea, insomnia and irritability - ironically, also symptoms of anxiety and depression. Some users report hot flushes, muscle twitches and vivid nightmares. "People need to realise herbal remedies need to be taken with due care and only after advice from a GP," warns Professor Edward Watkins, director of the Mood Disorders Centre at Exeter University. Even more dangerous, potentially, are the newly-fashionable benzodiazepines, which work by numbing the neurotransmitters that transmit fear to the brain. Prescriptions for Diazepam, commonly known as Valium, or "mother's little helper," as the Rolling Stones once dubbed it, stood at 5.2 million in Britain last year, a rise of nearly 15 per cent over the last five years. Newer variants such as Xanax, and Lorazepam, are more like the grandchildren of Valium and Miltown - a sedative that was so popular in the Fifties that it used to be handed around in dishes at parties like peanuts. A recent article in New York magazine suggests Xanax has become essential to Americans who fetishise anxiety, seeing fear as "the engine that... gives them an edge, that allows them to work weekends and at five o'clock in the morning, until at last it becomes too much. That's where the pills come in. Yet benzodiazepines are notoriously addictive and many untimely deaths, including singer Whitney Houston's and actor Heath Ledger's, have been linked to overdoses, especially when combined with alcohol. "Far too often GPs prescribe benzodiazepines for longer than the recommended two-to-four-week period or have patients withdraw from benzodiazepines too rapidly - both can be very dangerous," says medical solicitor Caroline Moore, who finds herself approached daily by people seeking legal action against those who prescribed them. Dangers aside, most doctors are keenly aware that - at best - prescribing drugs treats only the symptoms, rather than the cause of our woes. "If you're depressed because you're lonely and your doctor prescribes you antidepressants, which is all too easy for both of you, then all your distorted feelings of worthlessness and self-hatred will diminish to some extent, and you'll be able to function in day-to-day life," says Dr Keedwell. But it's not going to be a long-term solution to what made you depressed. The Government appears to have taken note and is now investing £400 million in "talking therapies," which, according to Prof Watkins, are by the far the best way to make us happier. "We shouldn't give people drugs to stop them getting heart disease, we should to teach them to lead healthy lifestyles," he says. In the same way we need to reach people prone to depression younger, ideally in adolescence, and teach them skills that make them less prone to depression and less likely to see it coming back. What skills could these be? Dr Guy Meadows runs the Sleep School, a London-based insomnia clinic, where he constantly sees clients who've been informed they are depressed. "Yesterday, three out of four clients had been prescribed antidepressants by GPs, who seemed automatically to assume insomnia was a symptom of depression, rather than wondering if it might work the other way around," he says. According to Meadows, the solution to both depression and insomnia (the NHS spent £50 million on sleeping pills last year) is actively managing such conditions. We need to take responsibility for them, to have a bit more self-awareness, to gain the ability to not see these conditions as something external that's attacking us, and that must be dealt with by another external factor. Meadows's technique, which is exciting mental health professionals everywhere, is mindfulness, which encourages sufferers to regard their negative thoughts with the dispassion of a Buddhist monk. The theory goes that by acknowledging anxieties, rather than trying to suppress them - with pills or through traditional therapy - they lose their power to control us. Despite some suspicion about its mystic aspects, The National Centre for Clinical Excellence now recommends mindfulness as an effective approach for depression. This generation, it seems, feels entitled to happiness, in a way that those who lived through two world wars do not. There needs to be a fundamental shift in our thinking. We need to recognise that low moods are part of the human spectrum of experience, not something dysfunctional," Meadows says. "Instead of thinking: 'I'm broken," we need to think: 'This is the way I'm feeling today but I can carry on with my life."" After all, a study by the mental health charity Mind showed that a simple walk in the park reduced depressive feelings in 71 per cent of people. As for me, I resisted my GP's call for Prozac. She eventually sent me to group counselling for women who'd had difficult births. Discussing my experiences in a sympathetic environment quickly put them in perspective. Luckily, my shouty baby slept through the night early. Within a couple of days I was my old, usually cheerful self. This is not meant to sound ungrateful to my GP, who went out of her way to help. Or to deny pathological post-natal depression exists. Or to dismiss the millions who sincerely believe antidepressants have saved their lives. In my case, however, all that was needed was a decent night's sleep.