Ever think "there aren't enough hours in the day"? Well now scientist are hoping to get over the need for a good night's sleep with new drugs which let you get just two hours' sleep a night and still wake up bright-eyed and bushy-tailed.

Other drugs could even allow you to go without any sleep for days.

"The more we understand about the body's 24-hour clock, the more we will be able to override it," said Russel Foster, a biologist at Imperial College London.

"In ten to 20 years we'll be able to pharmacologically turn sleep off."

Scientists are hoping to build on success of the drug Modafinil, a stimulant launched seven years ago which allows people to wake up refreshed after four hours of sleep.

Unlike caffeine or amphetamines, the stimulant appears not to leave you with jitters or euphoria followed by lows and does not leave a "sleep debt" to be repaid.

Since it was launched in 1998, sales have climbed from 21 million EURO in 1999 to 406 million EURO in 2005.

Also under development, by Cortex Pharmaceuticals of California, is CX717. Tests on 11 rhesus monkeys showed they were doing better after 36 hours continually wake than undrugged monkeys after normal sleep patterns.

The US military, whose special forces sometimes have to stay alert for 72 hours as a time, is very interested.

However, not everyone is impressed with the idea for a world where people can be active 22 hours of the day.

Neil Stanley, head of sleep research at the Human Psychopharmacology Research Unit in the UK, told New Scientist magazine: "I think that would be the most hideous thing to happen to society".