Monash University research has revealed one in three truck drivers has fallen asleep at the wheel within the space of just 3 months.

A survey of interstate truckies also found that 40 per cent reported sleepiness was a problem on half of all trips and fifty per cent of drivers also said despite knowing they're tired they get behind the wheel anyway.

The alarming results are the preliminary findings of Monash researchers compiling data on the sleepiness of professional drivers.

255 interstate truck drivers participated in the self-report survey and were asked to report on a variety of sleepiness-related experiences during the previous three months.

Department of Psychology study co-author Ray Misa said the research focused on why truck drivers continue to drive while they are sleepy.

"We found evidence to support the long-held beliefs that truck driversare under enormous pressure to meet delivery deadlines and these combined with their own perceptions on work performance can lead to continued driving regardless of how sleepy the driver feels," Mr Misa said.

"Drivers rated work regulations such as maintenance of logbooks and other organisational requirements as the greatest contributor to continuing to drive, this was closely followed by the need to meet schedules and deadlines. This was compounded by their inability to make a decision to stop and rest."

Researchers from the Department of Psychology hope to further analyse the behaviours of truck drivers and the reasons why they continue to drive while sleepy.

"We hope to raise awareness that sleepiness is the result of many factors which impact on performance and safety, as many of these may be overlooked in the research and management of driver sleepiness," Mr Misa said.

Ray Misa presented his findings to WorldSleep07 conference, hosted by the World Federation of Sleep Research and Sleep Medicine Societies (WFSRSMS) and the Australasian Sleep Association (ASA).