An Australian study of heavy-vehicle drivers who had recently crashed versus those who had not recently crashed yields some notable findings, reports Science Network Western Australia.

New research involving the Curtin-Monash Accident Research Centre has found that sleep apnea, while highly prevalent among heavy-vehicle drivers, is not associated with an increase in crashes.

However, the study did find a correlation between driving between midnight and 5:59am and a heightened risk of crashing, as well as driving for more than four hours without a break.