Drowsy Driving

Drowsiness.

Drowsiness while driving is a condition that affects everyone at one time or another. As drivers become tired, their ability to drive becomes impaired, and the risk of a collision rises. Driving while drowsy is dangerous because your senses and abilities become impaired. You may not see objects clearly, or in a timely manner. You may miss critical information — signs, lights, and sounds. It may also take you longer to process the information you take in or to make decisions in potential high-risk situations. You may misjudge speed and distances. In sum, drowsiness can affect every process involved in safe driving.

The risks.

Drowsy driving is one of the leading causes of traffic collisions. In 2020, NHTSA estimates that 100,000 police-reported crashes each year are the direct result of drowsy driving. This results in an estimated 800 deaths, 50,000 injuries. Unfortunately, driving while drowsy is not rare. In fact, according to the National Sleep Foundation’s Sleep in America poll, 60 percent of adult drivers say they have driven a vehicle while feeling drowsy in the past year. 1 in 25 drivers have admitted to falling asleep while driving. More than one in five fatal collisions involve a drowsy driver. Drivers may experience short bursts of sleep lasting only a few seconds (microsleeps) or fall asleep for a longer period of time. Either way, the chance of a collision increases dramatically.

Who is at risk?

Many drivers are at increased risk of becoming drowsy behind the wheel, including:

Drivers on long trips. Drivers could become fatigued while driving on long trips. Some drivers attempt to drive longer than they should on any given day.
Drivers lacking sleep. Drivers who are sleep deprived are more likely to fall asleep behind the wheel. According to the AAA Foundation for Traffic Safety, drivers may underestimate their drowsiness, leading them to stay behind the wheel instead of stopping for a 15–20-minute rest. Driving while drowsy is a dangerous form of impairment and does not improve with continued driving.
Drivers with undiagnosed or untreated sleep disorders. Drivers with sleep disorders are more likely to fall asleep while driving. Untreated disorders such as sleep apnea (stoppage of breathing due to soft-tissue blockage of the airway), narcolepsy (the inability to remain awake) and others can cause serious sleep disruption and uncontrolled nodding or falling asleep at the wheel. If you experience frequent daytime drowsiness, often have difficulty sleeping at night, and/or snore every night, consult your physician.
Drivers on the road during the body’s natural “low” times. Each person’s alertness, energy and sleep likelihood rise and falls throughout the day. This is referred to as the body’s “circadian rhythm,” the pattern of energy throughout a 24-hour period. Most people experience “lows” between midnight and 6 a.m. and again between approximately 2 p.m. to 5 p.m.
Drivers on the road after extended wakefulness. Remaining awake for extended periods of time can significantly increase drowsiness and its impact on driving ability. Research shows that being awake for 20 hours produces impairment equal to a blood alcohol concentration (BAC) of .05 percent. After 24 hours awake, the impairment rises to equal to a BAC of .10 percent.
Young drivers. Drivers under age 30 are involved in over two-thirds of all fall-asleep crashes. Additionally, these drivers are four times more likely to experience a sleep related crash than drivers aged 30 and older.
Shift workers. Drivers who work late-night or early-morning shifts are more likely to fall asleep while driving. Working the night shift increases collision risk by nearly six times. Rotating-shift workers and people working more than 60 hours a week need to be particularly careful.

Other causes of drowsiness.

Emotional stress, illness or boredom can cause drowsiness. Sun glare, a major factor in eyestrain, can also contribute to fatigue. Overeating, drinking alcoholic beverages, drug use or riding in a warm passenger compartment can all affect the likelihood of becoming drowsy.

Monotony, related to Fatigue.

Driving on an empty, straight road with no signals or billboards may seem like a simple task. Yet there is often not enough stimulation in the environment to keep you mentally alert. Compound this with the engine’s constant purr, the hum of the tires, the tendency to fix your eyes on a single point ahead and the general monotony of easy vehicle operation, and mental alertness drops. Under such circumstances, a driver is much more likely to doze off than when on a more difficult and demanding road.

How can you tell if you are at risk of drowsy driving?

There is no guarantee that you will recognize when you are at risk of driving fatigued behind the wheel. One half of drivers who crashed after falling asleep did not detect any signs of drowsiness before the crash. Be aware that there may be no warning before falling asleep, but recognize any warning signs that you may detect, including:

Difficulty focusing, frequent blinking or heavy eyelids.
Yawning repeatedly or rubbing your eyes.
Daydreaming; wandering/disconnected thoughts.
Trouble remembering the last few miles driven; missing exits or traffic signs.
Trouble keeping your head up.
Drifting from your lane, following too closely, or hitting a shoulder rumble strip.
Feeling restless and irritable.

Preventing drowsy driving.

To help prevent becoming drowsy, take the following steps before driving:

Get adequate sleep daily. While this varies from individual to individual, sleep experts recommend between 7 to 9 hours of sleep per night for adults and 8 to 10 hours for teens.
Prepare your route carefully to identify total distance, stopping points and other logistic considerations.
Plan to drive long trips with a companion driver. Passengers can help look for early warning signs of fatigue or take over driving when needed. At least one passenger should stay awake to talk to the driver.
Avoid medications (over the counter and prescribed) that cause drowsiness or otherwise impair performance.

Once you are on the road.

To help maintain your alertness while driving:

Protect yourself from glare and eyestrain with sunglasses.
Avoid heavy foods.
Be aware of your physiological down time during the day (circadian rhythm).
Have another companion driver (take out person) person ride with you and take turns driving.
Take periodic breaks. A good rule of thumb is to stop every 100 miles or every two hours.

On long trips, stopping periodically can temporarily offset fatigue. You should be able to drive a reasonable distance without difficulty if you stop for at least 10 minutes every two hours or every 100 miles and make regular stops for fuel, food, and restrooms. The concern with long-distance driving is that many people do not know, or choose to ignore, how much driving is too much. There is no rule to say how far you should drive at any given time, but no destination is worth the risk and consequences of drowsy driving. Do not overextend yourself. Determine a reasonable distance in advance and stop driving when you reach it.

Ineffective actions.

The following actions will not help prevent drowsiness longer than just a few minutes:

Trying to tough it out.
Playing music at high volume.
Driving at a faster or slower speed.
Chewing gum or eating.
Opening the windows/sunroof.
Products with caffeine
Smoking products
Turning up the AC

Rest is the key.

Remember, resting is by far the most effective way, and the only recovery strategy to counter drowsiness. It is not safe to sleep in a vehicle at the side of the road. Yet there may be times when it is better to pull off than continue driving. If you must stop along the roadway to rest, follow these practices:

Stop at a roadside area where security is present. If no such facility is available, make sure that you are as far off the highway as possible.
After dark, find a populated, lighted area.
Give yourself a little outside air but be sure that the windows are closed enough to prevent entry from outside.
Lock all doors and turn off your engine.
Turn on parking lights and turn off other electrical equipment.
After you rest, if safe to do so, get out of the vehicle and walk a few minutes to be sure that you are completely awake before you begin to drive again. Keep in mind that sleeping for more than 20 minutes can make you groggy for at least five minutes after awakening.

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