If you start each day desperately wishing for an extra hour in bed, the following is likely to leave you feeling even more grumpy.

Scientists have identified a 'sleepless elite' - a small group of people for whom a lie-in is a waste of time.

Rather than being tired, bad-tempered under-achievers, they are an energetic, outgoing and optimistic group who can happily and healthily get by on just four or five hours of shut-eye a night.

If that were not irritating enough, they tend to be slim, able to hold down two jobs at the same time, and breeze through their extra-long days without needing caffeine pick-me-ups or cat naps.

Working out how the gene cuts sleep without any obviousimpact on health could help in the design of drugs that give us all a few extra hours in our day.

The bad news is that while many of us get by on a few hours' sleep a night, just one to three people in 100 qualify to be part of the sleepless elite.

The research team is now appealing for members of the lucky group to come forward to allow their DNA to be studied.

University of California researcher Ying-Hui Fu said: 'My long-term goal is to someday learn enough so we can manipulate the sleep pathways without damaging our health.

'Everybody can use more waking hours, even if you just watch movies.'

Many of those who have already volunteered share fascinating characteristics. They are thinner than average, relentlessly upbeat and seem to have a high tolerance for physical pain and psychological set-backs.

Researcher Dr Christopher Jones told the Wall Street Journal: 'Typically, at the end of a long-structured phone interview, they will admit they have been texting and surfing the internet and doing crossword puzzles at the same time, all on less than six hours of sleep."

(Read by Renee Haines. Renee Haines is a journalist at the China Daily Website.)

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(Agencies)