Imagine it. You wander into the office, hand in your notice and disappear to the other side of the world for a year. Forget the career, forget the mortgage, blow the savings and just concentrate on having fun.

Sam Knight did more than just imagine it. Last January, she took off to Australia, worked and played her way up the east coast with some friends and only returned to this country last month when the cash started to run out. "I'd been meaning to travel ever since I left university," she says, "but I had so many debts that I had to start work immediately." She quickly got caught up in a career and for the next three and a half years worked as a media buyer.

In November last year, she decided she couldn't hack another winter commuting on the tube and that if she didn't do something about it when she had no real commitments, then she would never go. "I spoke to my boss and said I wanted to leave," she continues. "He told me I would be welcome back anytime, which was a great comfort, and armed with just my £1,000 bonus, one month's pay, the deposit from my flat and the £600 I got for the car, I was off." Simple as that.

Nor is Sam that unusual. Gap years for students are a well-established phenomenon, but the biggest growth in the market, according to Tom Griffiths, founder of gapyear.com, is now in breaks for those in employment. "Life is almost becoming a series of gap years," he suggests. "We come across those who are going before they have bought a property and dived into a long-term relationship, those who are settled and want to take off before they have kids, those who have had young kids and want to travel while they are still portable and amenable, those whose children have left home, and those who are retired. In short, a gap year is now an option for anyone who wants one."

In part, the gap year for "grown-ups" is a response to the me, me, me culture. Existential angst is no longer the preserve of self-obsessed youth; it's also been appropriated by the neurotic adult, and a gap year is just one response to a self-evaluation that finds something missing. You've got the car, the job, the relationship, the home, you've maybe even got the kids. But whatever the questions you've been asking yourself, these elements of your life don't provide the answer. So what do you do? You go somewhere else. Who knows, it might even work?

But there's also a sense that we're less prescribed by convention than previous generations. Our parents might have fallen for the notion that you work for 45 years and then collect the gold watch, but we're not going to. Youth is now a relative concept and you don't have to stop having fun just because you're getting older. Well, not necessarily. These days you're almost as likely to find a pair of 60-year-olds trekking in the Andes as you are to pass them on a stroll along Eastbourne seafront.

"The concept of a break is central to the natural world," says Joshua White in his book Taking a Career Break. "We spend a third of our lives sleeping at night to rejuvenate ourselves for the day. Why then should it be considered self-indulgent or lazy to take a chunk out of our working lives to pursue a different agenda? When work becomes onerous, stressful or dull and begins to swamp other interests, it might be time to reclaim our lives by taking a break."

The choice of destinations for career gappers is much the same as those for students - Australia, New Zealand, India, Africa and the US - though how people choose to allocate their time tends to vary greatly. "Younger gappers might want to drink their way up the Australian east coast," says Griffiths, "whereas older gappers might want to take a more leisurely tour of the Australian vineyards." Older gappers are also more likely to want to create their own itineraries than student gappers who might want to join a specific project.

Good preparation is key to getting the best out of your time abroad. This means sorting out the emotional as well as the practical issues. If you don't know why you're going or what you hope to get out of the trip other than a break from work, it's almost certain you'll end up in exactly the same place when you get back. This may be fine for some who are happy in their jobs and lives, but not for those who want to use the break to make some important life changes.

Unless you've won the lottery, it's generally not a good idea to leave your employment on bad terms. "Giving yourself a way back can make a gap year more relaxing," says Griffiths. "Many companies are becoming quite receptive to the idea of staff taking unpaid leave. In the current economic climate, firms are often happy to reduce their pay-roll, knowing they don't have to make any redundancy payments and will be able to take you back at a later date when conditions might have improved."

Sam Craig has been planning a year off ever since she visited Australia for three months last spring. She reckons that she will leave in a year's time. "I want to make sure everything is settled before I go," she says. "I want my debts paid off, I want to have saved at least £6,000, and I want to make sure my flat is let out and that the mortgage will be paid. I feel that life's short, the world's big and the daily grind from Forest Hill to London Bridge is starting to do my head in. My mum and dad are concerned that I might be damaging my career, but most of my friends are all for it. I want to open myself up to new possibilities."

This is something James Burgess knows all about. Over the years, he has worked as a firebreather, a hypnotherapist, and is now managing director of Klondike, a media strategy consultancy with close links to advertising agency St Luke's. At various times in his life, he has taken significant breaks to reflect on his life. At one time, he rented a small house in the Caribbean for four months to try his hand at writing. "Nothing great came out of it," he says wryly, "though I learned a lot about myself." On his most recent break, 3 years ago, Burgess used the time to consider why he always ended up not getting on with big companies. "I realised that if I was going to enjoy work I had to be self-employed." He came back, set up Klondike and has never been happier in his career.

Returning from a gap year can be even more traumatic than leaving. The experts suggest coming back with enough spare cash so you have time to consider your options and aren't bounced into the first job that comes along. All those good intentions that seemed so certain when you were on that beach can easily disappear when the bills start coming in.

Sam Knight is now back at her old job. "In some ways it feels as if I never went away," she says, "but deep down I know that something has changed. Even though my work is fairly stressful, I feel more relaxed about it. A job is just a job, and work isn't everything."

How to make the most of your time off

Most people choose to travel independently. However, if you want to try something new, volunteer or want something more structured, www.gapyear.com recommends the following.

i-to-i
Specialises in Teaching English as a Foreign Language training and volunteer placements overseas.

The Leap
Organises placements focused on tourism combined with conservation and community projects. You might be part of a team providing game walks in Zambia, horse safaris in Botswana, camel and balloon safaris in Kenya, trekking and rafting in Nepal, deep-sea fishing off Zanzibar or quad biking in Namibia.

MAD Venturer
Assists in community development, while at the same time enabling travellers to gain experience through work and adventurous travel. Specialises in group and solo projects.

Changing Worlds
Offers a variety of cultural experiences, including teaching in Africa, paid work in the US and farm work in New Zealand.

Global Vision International
Offers conservation expeditions, research projects and voluntary work around the world .Projects include marine conservation expeditions in Mexico, volunteering with street children in Ecuador, and China and Amazon rainforest expeditions.

International Academy
Blends sport and travel by enabling you to gain coaching or instructor qualifications in a range of sporting activities, from snowboarding to soccer, in different locations around the world.

Top tips

· A career break is easier in practical terms than you might imagine. A six-month trail through Africa or Asia might not be any more expensive than living at home.

· Set up direct debit arrangements for TV licence, water rates and all other bills that might arrive in your absence. Cancel any standing orders you don't need.

· Check how much flexibility is built into your mortgage and pension plans.

· Renting your property through an agency may cost you 10% of the income, but it can offer peace of mind. Don't forget to tell your mortgage lender that you are renting your property.

· Remember that rental income, minus mortgage payments and agency fees is liable to tax. Working out your tax liabilities if you are going to be out of the country for more than six months can be tricky, so get help if you need it.

· If contemplating an ambitious trip, try taking a few shorter ones closer to home first to see if you can stand your own company.

· If you are planning to return to your old job, it is worth keeping in contact with your workplace while you are away, to demonstrate you haven't forgotten them and you are committed to coming back.

· If you want to use the break as a new start, leave yourself enough time and money on your return to make the changes so you are not forced back into old routines.