Driving While Drowsy is Dangerous

Sleepy driving may mean an untreated sleeping disorder or too little sleep

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) The dangers of drunk driving receive wide attention. But the dangers of drowsy driving are significant as well. Furthermore, sleepiness while driving may point to other health issues.

The US Centers for Disease Control and Prevention reported on the rate of drowsy driving based on a survey of nearly a third of the states.

They found 4.2 percent of respondents said they had fallen asleep at least once while driving in the past month. Estimates of accidents that may be caused by drowsy driving range from 15 to 33 percent.

"Don't drive while sleepy."

The CDC analysis, led by Anne G. Wheaton, PhD, came from the Behavioral Risk Factor Surveillance System survey conducted in 2009-2010 among 147,076 individuals in 19 states.

A total of 4.2 percent of the respondents answered yes to the following question: "During the past 30 days, have you ever nodded off or fallen asleep, even just for a brief moment, while driving?"

Those who weren't sure or didn't drive were not included in this percentage. A higher percentage of men (5.3 percent) than women (3.2 percent) reported drowsiness while driving.

The highest numbers of drowsiness occurred among those aged 18 to 44.

Among those aged 65 and older, only 1.7 percent reported being sleepy while driving.

Those most likely to say they had driven while drowsy were those who got 6 or less hours of sleep, those who snored and those who sometimes accidentally fall asleep during the day.

Among those who got 6 or less hours of sleep, 6.7 percent reported drowsy driving, compared to 2.6 percent of those who got 7 to 9 hours of sleep.

Among those who said they had fallen asleep by accident during the daytime at least once in the past month, 8.6 percent reported driving while sleepy, compared to 1.8 percent who had not unintentionally fallen asleep during the day.

A total of 5.6 percent of snorers reported sleepiness while driving, compared to 3.2 percent who do not snore.

Snoring is one symptom of sleep apnea, a sleep disorder in which a person does not breathe continuously the entire time they are asleep. Untreated sleep apnea is linked to various health risks, including daytime sleepiness.

A commentary accompanying the report noted even being drowsy itself is dangerous while driving, even if a person doesn't actually nod off.

"Although it is clear that falling asleep while driving is dangerous, drowsiness impairs driving skills even if drivers manage to stay awake," the authors wrote. "Drowsiness slows reaction time, makes drivers less attentive, and impairs decision-making skills, all of which can contribute to motor vehicle crashes."

The National Highway Traffic Safety Administration reports that 2.5 percent of all car crashes resulting in a fatality involve sleepy drivers (730 crashes in 2009).

Sleepy driving accounted for 2 percent of all crashes with nonfatal injuries, the agency reported (about 30,000 crashes in 2009).

Prevention relies on addressing the conditions that lead to sleepy driving, including those with untreated sleeping disorders or those driving while taking medications that cause drowsiness.

According to William Kohler, MD, the director of the Florida Sleep Institute at Spring Hill, Florida, sleepiness while driving may be an indication of an undiagnosed sleep disorder.

"People that become drowsy while driving need to be evaluated for potential underlying sleep problems that could be contributing to this," Dr. Kohler said. "Drowsy driving is serious and leads to signify mortality and morbidity, but it is preventable if appropriate evaluation and treatment is carried out."

Dr. Kohler also noted that drowsy driving may be more common than this study reveals. "This was a self-report, so most likely, the incidence of drowsy driving is significantly higher than the report in this particular evaluation," he said.

Prevention also means not driving if you have gotten insufficient sleep, which is anything less than 7 to 9 hours each night. If you suspect you may have a sleeping disorder, you should seek treatment.

If you do find yourself becoming drowsy while driving, it's essential to pull over to rest or switch out drivers.

Symptoms of drowsiness while driving include yawning or blinking often, forgetting the most recent miles you drove, hitting the rumble strip, drifting out of your lane or missing your turns or exits.

"Techniques to stay awake while driving, such as turning up the radio, opening the window, and turning up the air conditioner, have not been found to be effective," the authors write.

The report was published January 4 in the CDC's Morbidity and Mortality Weekly Report.

Reviewed by: 
Review Date: 
January 2, 2013
Last Updated:
January 11, 2013