Last December, Richard Pickering flew to Hawaii to run the Honolulu marathon. Then he went skiing for six weeks in Val D'Isère. After this he did some athletics coaching in Portugal before heading off for a month in Canada. He stopped in Britain to watch the London marathon and then went to LA, Las Vegas, New Zealand and Australia.

The 44-year-old didn't have to worry much about money during his journey because he was on a fully paid six-month sabbatical from his employer, John Lewis.

The British department store chain is one of a number of organisations that offers employee sabbaticals. They are called long leave and consist of six months leave after 25 years of service.

The policy was instituted in 1977, says Darren Sargent, general manager of employment policy, and, as careers of between 25 and 45 years at the company are not unusual, was designed to be a mid-career break.

He adds that there are no restrictions on what you can do or when you use it.

Another business that has a similar policy is Happy Computers, an IT training company. Every six years employees can take a paid month off.

"Most people combine it with holiday or maternity leave," says Henry Stewart, the company's founder and chief executive.

"Our training manager has just come back from three months in South America. Other people do voluntary work or even just stay at home."

While few companies offer large chunks of paid leave and those that do usually only offer them to those who have worked at the company for years, many more businesses give unpaid leave after far shorter periods of service.

Eversheds, a British-based law firm, allows staff who have worked for at least three years to take up to 10 months off. Employees at the Royal Bank of Scotland can take both short and long employment breaks. In fact, they can even request an unpaid break of up to three years.

Companies may simply be responding to a growing appetite for taking long breaks. Recent research by British insurer Norwich Union showed that 63 per cent of employees wanted to take a sabbatical, while 25 per cent wanted to do so in the next year.

"We've seen huge growth in career breakers between the ages of 25 to 45," says Jo Little, a spokeswoman for volunteer travel provider i-to-i.

"Most of them are taking a sabbatical from a full-time job - three to six months is typical."

Moreover, she says, many in their 40s and 50s are seeing their children taking gap years and realise they can do the same, thinking, "I want a bit of that too".

But why do employers allow potentially vital workers to disappear for long periods? One argument is that the post-sabbatical employee returns refreshed and with a different perspective, but it is also a way of retaining people. If somebody has itchy feet after six or seven years with the company, it may be far wiser to give them six months off than to say goodbye and be forced into a costly recruitment process for a replacement.

However, sabbaticals are not without their pitfalls. Absent workers need temporary cover. Their effectiveness also depends on the nature of the business.

"For some companies it's a luxury that operationally they can't afford," says Chris Charman, a consultant at Towers Perrin. "For others it can work very well. It really depends on the culture of the place."

He adds that a sabbatical is often perceived as more valuable than its actual cash cost to the company, making it a good perk to offer.

He warns, however, that giving staff the time to disappear off and reflect on their lives can have unintended consequences. "One company we worked with had a very loyal employee of 20 years who took 18 months off to go around the world. He came back to work and four months later emigrated to Canada," he says.

Opponents of excessive executive rewards may take comfort in the fact that, at John Lewis at least, there is one group of employees to whom the luxury of long leave is not extended: those who sit on the company's boards.

They are deemed too critical to spend six months reflecting and discovering themselves - but are permitted to retire six months early instead.