TORONTO — Driving while tired is more common than driving under the influence and is a much bigger problem than previously believed, according to a recent report on highway safety.

And it’s not just truckers who are the culprits.

Driver fatigue could be the cause of almost one in five fatal crashes noted the report produced by the Highway Safety Roundtable, which compiles some of the latest available research on the consequences of driver fatigue. According to the study fatigue is linked to the deaths of some 400 Canadians every year.

“The message is very clear that a lot more Canadians are driving tired on our roads than anyone has ever thought before, or ever wanted to admit before, and it is a very serious road safety issue,” said Mark Yakabuski, president of the Insurance Bureau of Canada. “We really have to be a lot more aware of the dangers of fatigue than we have been up until now.”

Research based on Ontario traffic data suggests a long day at work could be triggering collisions, since most accidents involving fatigue occur between 3 p.m. and 6 p.m. and on Fridays. The most fatal fatigue-related crashes occur between 1 a.m. and 7 a.m., Yakabuski said.

Fatigue is likely being under-reported, because police don’t have a good way to determine when it is a factor in a crash — unless drivers admit they were fatigued, said Yoassry Elzohairy, senior safety research adviser for the Ontario Ministry of Transportation.

Police reports suggest fewer than two per cent of all collisions are believed to be fatigue-related. But a 2005 study also found one in five drivers admitted to falling asleep behind the wheel during the previous 12 months.

By eliminating incidents that are clearly linked to factors like vehicle condition, speed, drug or alcohol impairment and weather, Elzohairy estimated that 17.8 percent of all fatal crashes and 25.5 percent of crashes causing injury on Ontario roads in 2004 were fatigue-related.

— with files from the Globe & Mail