Driving tired and sleepy is dangerous and may harm or kill people
June 2010

Drowsy driving, the dangerous combination of sleepiness and driving, or driving while fatigued, while operating a motor vehicle, is becoming a growing problem.

In a sense, drowsy driving is similar to driving under the influence, as sleepiness results in a slower reaction time, decreased awareness, impaired judgment and an increased risk of getting involved in an accident, resulting in unnecessary deaths or injuries to innocent people.

Getting behind the wheel on an insufficient amount of sleep poses a significant risk to not only the driver, but to others sharing the road. Sleep deprivation may affect a driver's awareness of his or her surroundings, as well as reduce one's ability to react to situations in time.

As a result, this endangers the lives of themselves – and others – by increasing the likelihood of causing an accident.

Nearly nine out of every ten police officers responding to an AAA Foundation for Traffic Safety Internet survey reported they had stopped a driver who they believed was drunk, but turned out to be drowsy. The survey was coordinated with the National Highway Traffic Safety Administration.

Sleep is an essential component of our everyday lives. When you sleep, your body recharges itself so that you wake up feeling refreshed. The amount of sleep you get affects everything else you do: how you think, how you feel, how you perform, and even how you drive.

The American Academy of Sleep Medicine (AASM) offers the following tips for people to avoid sleepiness while driving:

• Get enough sleep

AASM recommends that adults get seven-to-eight hours of sleep each night in order to maintain good health and optimum performance.

• Take breaks while driving

If you become drowsy while driving, pull off to a rest area and take a short nap, preferably 15-20 minutes in length.

• Consume caffeine

Caffeine improves alertness in people who are fatigued.

• Do not drink alcohol

Alcohol can further impair a person's ability to stay awake and make good decisions. Taking the wheel after having just one glass of alcohol can affect your level of fatigue while driving.

• Do not drive late at night

Avoid driving after midnight, which is a natural period of sleepiness.

Those who think they might have a sleep disorder are urged to discuss their problem with their primary care physician, who will issue a referral to a sleep specialist.

Research has shown that sleepy drivers are eight times more likely to crash. Definitely driver sleepiness are a risk of serious injury to car occupants.

They found an eightfold increased risk if drivers reported sleepiness, an almost threefold risk for drivers who reported five hours or less of sleep in the previous 24 hours, and a five fold risk for driving between 2am and 5am.

Reducing these three behaviors may reduce injuries or death by up to 19%, say the authors. It also provides some simple messages with regard to specific driver behaviors in place of general advice against driving while sleepy, they conclude.

Unfortunately further research shows that people keep driving even when they know that they are sleepy. This has important implications for public safety, say the researchers of a large study published on BMJ-British Medical Journal

Studies have shown that sleepiness in drivers is an important factor contributing to the burden of traffic related injury and death. Estimates of the proportion of car crashes attributable to sleepiness range from 3% to 33%, but little is known about the extent to which drivers are able to assess that they are sleepy while driving.

Researchers in France examined the association between self reported driving while sleepy and the risk of serious road traffic accidents (RTAs) in 13,299 middle aged drivers. They collected data on sleepiness and other driving behaviors in 2001, and serious RTAs in 2001-3. Socioeconomic status was recorded, and a range of other factors that could affect the results were taken into account.

In answer to the question "in the past 12 months, have you ever driven while sleepy?" 63% of participants responded never, 36% a few times in the year, 0.8% about once a month, 0.3% about once a week, and 0.2% more than once a week.

There was a strong association between self assessed driving while sleepy and the risk of serious road traffic accidents over the next three years. This risk increased with reported frequency of driving while sleepy.

For example, participants who reported driving while sleepy "a few times in the year" were 1.5 times more likely to have been involved in a serious RTA compared with those who reported not driving while sleepy over the same period. And those who reported doing so "once a month or more often" were nearly three times more likely to have been involved in a serious RTA. Further analysis did not change this association and follow-up questionnaires in 2004 also found a similar trend.

These results clearly show that self assessed driving while sleepy is a powerful predictor of serious road traffic accidents, and suggest that drivers are aware that they are sleepy when driving but do not act accordingly, say the authors. Drivers may either underestimate the impact of sleepiness on their driving performance or overestimate their capacity to fight sleepiness.

Messages on prevention should therefore focus on convincing sleepy drivers to stop driving and sleep before resuming their journey, they conclude.

Another important study in the journal Sleep finds that sleepy driver near-misses may predict accident risks.In the first known scientific study into the important question of near-miss sleepy accidents and their association with actual accidents, a study published in the journal SLEEP found that sleepy near-misses may be dangerous precursors to an actual accident.

The study focused on a study sample of 35,217 individuals. The results obtained showed that a total of 1.3 percent of all participants reported at least one accident associated with being sleepy over the preceding three years. Near-miss accidents associated with sleepiness were reported in 18.3 percent of the sample (10.6 percent with one sleepy near-miss, 5.9 percent with two-to-three sleepy near misses and 1.8 percent with four or more sleepy near-misses).

"Little attention has been given to sleepy near-miss driving accidents up to now despite their likely relationship with actual driving accidents," said Nelson B. Powell, DDS, MD, of Stanford University, one of the authors of the study.

"Although there have been investigations that included near-miss accidents and/or sleepy near-misses, these data were limited and not used to predict a sleepy accident.

This study indicates that near-miss sleepy accidents are common and dangerous.

"The near-miss sleepy accidents occur in 14 times more people than actual sleepy accidents, and the near-misses appear to predict who is at risk for any type of actual accidents in a dose-response fashion."

Bibliography - Sources

1. BMJ-British Medical Journal
2. American Academy of Sleep Medicine (AASM)
3. National Highway Traffic Safety Administration