A new sleep study found that 41% of Australian truck drivers have obstructive sleep apnea.

The study, published in the journal "Sleep," found that although only 4.4% of drivers reported a previous diagnosis of sleep apnea, an at-home diagnostic test found that 41% of the 517 drivers who participated likely had sleep apnea.

The study also found that 36% of drivers were overweight, 50% obese an 49% were cigarette smokers.

"Sleep apnea remains a significant and unrecognized problem in CMV drivers, who we found to have multiple health risks," the study says. "Objective testing for this sleep disorder needs to be considered, as symptom reports and self-identification appear insufficient to accurately identify those at risk."

Although the study focused only on Australian drivers, NPR reported that as much as 30% of American drivers are believed to have sleep apnea, a condition that causes a person to stop breathing for short periods of time during sleep, which results in daytime drowsiness.