In the U.S. about 20 percent of all motor vehicle crashes are caused by tired drivers, the researchers said in JAMA Pediatrics. That translates into about 1 million crashes, 50,000 injures and 8,000 deaths every year.
“It’s a big issue that hasn’t had a lot of rigorous research. So lawmakers and policymakers may not have chosen to act on this because there wasn’t much evidence,” Martiniuk said.
For the new study, the researchers used data from a study of about 20,000 Australian drivers who were between the ages of 17 and 24 years old.
The young drivers were surveyed about their sleep habits between June 2003 and December 2004. The researchers then used government records to see which drivers were in an accident over the next two years.
Overall, about 9 percent of the 2,156 drivers who got less than six hours of sleep ended up in a crash. That compared to about 7 percent of the 17,171 who slept more than six hours.
But those who reported less than six hours of sleep also had other traits that may increase their risk of a crash. For example, drowsy drivers also drove the most, which may put them at an increased risk of a crash.
After adjusting their numbers for those additional risk factors, the researchers found that drivers who got less than six hours of sleep were still at a 21 percent increased risk of a crash.
“I am not surprised at the results as young adults are frequently sleep deprived as are many in our population,” Dr. Steven Scharf, director of the University of Maryland Medical Center’s Sleep Disorders Center in Baltimore who was not involved with the new study, told Reuters Health by email.
NIGHTTIME DRIVING BAN?
Martiniuk and her colleagues also found that sleeping less was tied to more accidents occurring between 8 p.m. and 6 a.m.
“That should open the discussion of bans on nighttime driving,” Martiniuk said.
Dr. Beth Ebel, director of the Harborview Injury Prevention and Research Center at the University of Seattle, said that nighttime driving bans and other restrictions on graduate licenses have been effective in some U.S. states.