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Driving While Sleepy

Driving While Sleepy

It’s been a long, difficult shift at work, and your eyelids are heavy as you get in your car and get ready to drive home. Yawning, you set the air conditioning to “cool” and turn on the radio for noise. Like 60% of Americans you’ll be driving home while battling the urge to fall asleep.

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.

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. If you snore or suspect sleep apnea you now have a viable alternative to traditional sleep labs! Thanks to advances in micro-technology and pulse oximetry you can consider home sleep testing as an alternative to a traditional overnight sleep study.

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.

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.

Driving while sleepy can be very dangerous. Approximately 100,000 accidents and 1,500 deaths a year are attributed to drowsy driving or falling asleep behind the wheel.

When polled, about 20% of Americans reported dozing off for short periods of time while driving and 10% reportedly fell asleep entirely while driving.

Research has shown that, for many people, not sleeping for 18 hours can impair driving as much as being legally intoxicated. Falling asleep at the wheel or dozing even for just a few seconds can seriously harm you or others around you. When traveling at 70 mph, if a person dozes for only 2.5 seconds he has traveled the length of a football field.

Those at highest risk for drowsy driving include young people between the ages of 16 and 29, shift workers, and those with undiagnosed sleep apnea and narcolepsy. Younger people, especially males, have been reported to have a higher risk of accidents due to lack of sleep. This can partly be due to increased activity late in the evenings and not maintaining a stable sleep-wake cycle. Shift workers, especially third-shift workers, are at risk because their sleep-wake cycle is frequently altered. These workers also tend to get poor sleep and have increased interruptions in their sleep due to their work schedule. People with undiagnosed sleep apnea and narcolepsy are also at a high risk for incidences of drowsy driving. Sleep apnea and narcolepsy can cause severe fatigue and increased daytime sleepiness. People with these disorders are often sleep-deprived and have difficulty staying awake even during the daytime.

Signs You Are Too Drowsy to Drive:

Heavy eyelids

Impaired concentration

Missing off-ramps and traffic signals

Frequent yawning

Drifting into other lanes

Jumpiness and irritability

Main Causes of Drowsy Driving:

Long-term and short-term sleep loss

Medications that increase drowsiness or cause fatigue


Sleep disorders that are untreated

Driving patterns (those that involve driving mostly after midnight and before 6am)

Fragmented sleep

Breathing interruptions during sleep

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