Sleep Care

The Consequences of Driving While Sleepy

We’re in the middle of the holiday season and a majority of Americans will be driving across the country to be with family and friends. Like 60% of Americans you might be battling the urge to fall asleep while at the wheel.  If you happen to have sleep apnea—a condition that causes severe daytime sleepiness and fatigue—then you’re three to five times more likely than normal to get into a serious crash involving personal injury.  Such an occurrence is fairly common:  according to the National Highway Traffic Safety Administration, crashes because of drowsy driving claim at least 1,550 lives, produce 71,000 injuries, and cost $12.5 billion each year.

The Facts About Drowsy Driving

Drowsy driving crashes typically occur during two time periods:  from midnight to six in the morning, when the body’s need for sleep is very high, and in the mid-afternoon, during the “circadian dip”—a period where the body’s changing internal rhythms cause naturally lower energy levels and a tired feeling.  Drivers involved in crashes due to drowsiness tend to be male, driving alone.  They also tend to be young: one estimate is that 55% of all crashes where a driver fell asleep involved drivers twenty-five years old or younger.  Jobs with workers most at risk for sleep-related crashes include any kind of shift work and commercial drivers—although with enough sleep deprivation, or a long and boring trip with no rest breaks, any driver can be at risk.

Poor Sleep = Poor Driving

Driving is very complex activity utilizing extremely heavy and powerful equipment that requires high levels of alertness, decision-making and quick reactions.  Studies investigating the effects of poor sleep leading to daytime drowsiness have found that participants experienced slower reaction times, impaired judgment and vision, problems with short-term memory and the information processing necessary to make quick decisions, and decreased alertness.  Additionally, fatigue can lead to increased moodiness and aggressive behavior—which for drivers may translate into “road rage” and further place themselves and those around them at greater risk for a crash.  Microsleeps—brief episodes of sleep during conscious wake—are also common, and can contribute to a driver feeling like they’re on “autopilot” and not maintaining awareness of road conditions.

Legal Consequences of Drowsy Driving

Currently, only the state of New Jersey has a law that makes it a crime to drive while “knowingly fatigued”, which is defined as being awake for more than twenty-four consecutive hours.  The law went into effect in 2003, although similar bills are pending in Illinois, Kentucky, and Massachusetts.  If found guilty, offenders may be punished by up to ten years and prison and a $100,000 fine. 

Enforcement of the law typically relies on drivers’ responses to questioning if stopped, although drivers cannot be stopped merely because they were tired.  However, in studies comparing the two, tired drivers perform as poorly or worse as drivers who are intoxicated.  For example, after twenty-four hours of sustained wakefulness, driving performance is equivalent to having a blood alcohol content of 0.10%–which is 0.02% higher that what is considered legally drunk in every state.

Sleeping Soundly, Driving Safely

There are several practical steps that can be taken to prevent drowsy driving from becoming a problem.  An important starting place is to ensure that you’re getting enough sleep—the recommended amount for adults is between seven to nine hours a night, and for teens eight to nine hours a night. Those with sleep apnea may be sleeping for eight to nine hours, however sleep apnea sufferers are often unaware of the unconscious interruptions in sleep that take place hundreds of times each night, preventing restful sleep and causing dangerous levels of daytime fatigue. If you suspect you may be suffering from sleep apnea talk to your physician and investigate treatment options if needed.

When driving, make sure to take breaks on long trips—a good guideline to follow is to stop every 100 miles or two hours.  If possible, have someone in the car with you who can talk (to avoid daydreaming or mind-wandering) or take over the driving if needed.  Do not drink alcohol or take sedating medications before driving.  If you’re driving alone and feel tired, pull over on the side of the road or at a rest stop and take a short, fifteen to twenty minute nap—sleeping for longer periods of time typically leads to a groggy feeling that takes a while to pass.

Caffeine can be used in small doses to help improve awareness.  For example, two cups of coffee usually need about thirty minutes to take effect, and will generally provide increased levels of alertness for several hours.  Be careful of consuming too much caffeine, as a “crash effect” can occur when it wears off that will make the concentration and focus needed for driving much more difficult.

If none of the above provide sufficient or effective alertness, car pooling with others or riding the bus can be considered as way to get to where you need to go safely without having to worry about the dangers of driving while being drowsy behind the wheel.