By Monash University, [RxPG] The two cognitive neuroscientists, who are studying the problem of excessive daytime sleepiness, believe that up to 770,000 people in Australia may experience drowsiness during crucial, everyday tasks.
"Many of these people are at double jeopardy - as drivers and as machinery operators or farm workers," said Psychology department researcher Dr John Reid.
"Overseas studies show that between five and nine percent of the adult population experiences periods of irresistible sleepiness at least three times a week," he said.
"It is interesting to note that in countries where people take an afternoon siesta, that percentage falls dramatically to about one per cent."
Dr Reid and Professor Stuart Armstrong of the Epworth Sleep Centre, have conducted initial research and they have now joined the Faculty of Medicine, Nursing and Health Sciences to continue their study.
"Many people, including health professionals are surprised to find that such a high percentage of people are sleepy such a lot of the time," Dr Reid said.
Sleepiness - not just going to sleep - is a significant risk factor that is under-recognised, particularly by many doctors, the researchers claim.
They stress that excessive sleepiness is not the same as fatigue. "You can be fatigued without being sleepy, and you can be sleepy without having done anything to make you tired," Dr Reid said.
Excessive sleepiness may be caused by sleep disorders such as insomnia, medical conditions including diabetes and sleep apnoea, neurological conditions such as narcolepsy, or through lifestyle factors.
The scientists are about to do a further study into the prevalence and causes of wake-time sleepiness in adults in Victoria.