Getting eight hours' sleep a night has long been seen as one of the keys to a healthy and happy life.

But for most of us the figure is little more than an ideal, with the average worker losing two and a half years of sleep over the course of their career, according to a survey.

In fact, the average working adult loses just over ten hours' sleep every week, which adds up to more than one complete night's rest.

That adds up to 520 hours over a year or 23,140 hours (2.5 years) over the average working lifetime.

Only 3 per cent of professionals get their eight hours every night of the working week, the study found.

Company directors are the most sleep-deprived of all, with 8 per cent getting under four hours of rest per night, according to Travelodge's 2007 sleep study.

The budget hotel chain surveyed more than 5,200 individuals from 30 different careers to discover more about how work affects rest.

The majority of those questioned were getting fewer than the recommended eight hours every night.

Those in the travel industry, such as cabin crew and pilots, found it hardest to get to sleep - 86 per cent struggled with sleepless nights.

Teachers were the most likely to stay awake because they were worrying about their work (39 per cent).

Some 86 per cent of those employed in public relations or marketing said they got enough sleep - but that might be because 95 per cent of them said they fell asleep on the sofa once they get in from work.

Wayne Munnelly of Travelodge said: "A notable trend has emerged from the top ten list of sleepdeprived professions. The majority work everchanging shifts which are notorious for confusing your body clock meaning disrupted sleep.

"In order to stay healthy and alert when working shifts it's important to be organised and plan time for sleep in advance."

Lack of sleep has been linked to obesity and high blood pressure as well as more obvious symptoms such as poor concentration.

The report said the top 10 most sleep-deprived professions are:

Company directors (averaging 5.9 hours of sleep a night)

Ambulance crew/paramedics (6 hours)

Tradesmen (6 hours) Leisure and hospitality workers (6 hours)

Police officers (6.1 hours)

Factory workers (6.2 hours)

Nurses (6.3 hours)

Engineers (6.3 hours)

Doctors (6.4 hours)

Civil servants (6.4 hours).