Designed by two University of Limerick (UL) students, Casper . . . a unique device that monitors the sleep patterns of astronauts . . . was launched into space on board the shuttle Discovery last night.

Dr Derek O'Keefe, from the department of electronics and computer engineering in UL, told the Sunday Tribune, "We have a great sense of achievement that our project will be the first ever completely Irish life science experiment in space. It will be great to look up at the sky and say to ourselves that we have got a device we developed ourselves into space.

We are absolutely delighted that it has gone ahead."

The Irish experiment will travel with Discovery to the International Space Station (ISS), where an astronaut will wear a special vest designed to monitor his sleep patterns over a period of 150 days.

"The quality of sleep, or more particularly the poor quality of it, is a major issue for Nasa and the European Space Agency (ESA) and one of the big stumbling blocks of longdistance space travel, " said O'Keeffe.

"An astronaut in orbit finds it very difficult to get a good night's sleep. There is no gravity to keep you in the bed and even worse, your system has to cope with 16 sunrises and 16 sunsets in a 24-hour day. Disturbed sleep is not refreshing and leaves flight crews feeling sleep-deprived and less able to concentrate."

Shuttle and space-station crews are currently given sleeping pills to help them catch some shut-eye but little data is available on how this enforced sleep compares to normal sleep on earth.

O'Keeffe and his UL colleague Dr Marc O'Griofa, who was a medical student at UCD when they started the project, hope to greatly improve this situation with their Casper experiment.

They sent a proposal to the European Space Agency suggesting substituting the traditional method of monitoring sleep with a special shirt or vest called the LifeShirt.

O'Griofa outlined that anyone who has suffered jet-lag after a long-distance flight and relocation in a different time zone will be familiar with the sleep disturbance experienced by astronauts. "Our bodies have internal clocks working to a circadian rhythm. This clock sets itself to the rise and fall of the sun, " he explained.

"Research has shown that our circadian rhythm can deal with the kind of disturbance experienced by astronauts for as much as 100 days. After this the body can't cope anymore and the rhythm goes seriously out of sync.

"One of the big difficulties of long-distance space flight beyond the 100 days is that the circadian pattern begins to deregulate."

It is hoped that after Casper spends 150 days in space much more will be known about the best ways to deal with the problems of sleep deprivation among astronauts.