Ambitious professionals are sacrificing their personal lives and ignoring their children because of a new phenomenon - "the extreme job".

Research, published by the Harvard Business Review, identifies this new type of worker who regards a 10-hour day at work as part-time.

It is "wreaking havoc on private lives and taking a toll on health and well-being", the research warns.

The research estimates 45 per cent of high-earning people working for large global companies have "extreme jobs" despite the ferociously tough qualifications.

For starters, an extreme job involves working at least 60 hours a week, although many work 100 hours or more.

Holidays are a rarity. Nearly half take 10 or fewer days' holiday every year, and "regularly" cancel time-off if something comes up at work.

In fact, work is so important that people with "extreme jobs" have made sacrifices which would shock anybody who is not a workaholic. The wife of one "extreme worker" said: "The first year we were married, we had to rearrange my grandmother's funeral so that he wouldn't miss a meeting."

One executive admitted he had lost all credibility with his elderly, wheelchair-bound father because he was always cancelling his planned weekend visits.

Another man said he had lived in his flat in South Kensington, London for two years, but had only ever bought a mattress and a sleeping bag.

"His schedule was such that he hadn't been able to make a commitment to be home to accept a delivery," the authors, Sylvia Ann Hewlett and Carolyn Buck Luce said.

The biggest losers are the spouses and young families of workers with extreme jobs.

Nearly half of men and women who took part in the internatinonal research project said their jobs "interfere with having a strong relationship with my spouse/partner."

In a shocking admission, it warns: "At the end of a 12-hour or longer day at work, 45 per cent of all respondents in our global companies survey are too tired to say anything at all to their spouses or partners."

The same number said that their jobs, which involves regular travel and evening entertainment, make it "impossible" to have a "satisfying sex life."

The results were equally worrying when the workers were asked about the impact that their jobs have on their children.

They were asked: "Has your child ever experienced any of the following because of the number of house you work?"

All parents admitted that their long working house mean their children regularly watch too much television, eat too much junk food and have discipline problems.

In a surprising twist, the research concludes that people with "extreme jobs" do not hate their work. They love it.

They do not feel exploited - they feel exalted.

In fact, the article is illustrated by a man running in a hamster wheel with a large grin on his face.

It says: "They brag about pulling all-nights and about flying 300,000 miles in a year.

"Far from seeing themselves as workaholics in need or rescuing, extreme workers wear their commitments like badges of honour."

Asked why they do their jobs, more than 80 per cent of both men and women said they find them stimulating and challenging. Earning a fortune was ranked as the third most common reason.

Extreme jobs are found in all sectors of the economy, such as the City, entertainment, media, medicine, law, accounting and consulting.

A typical worker with a full-time job does a 37-hour week, according to the Office for National Statistics.