Drowsy Driving

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Drowsy driving can be a risk to anyone who gets behind the wheel of a car. It is the cause of at least 100,000 auto crashes each year. There are easy steps you can take to prevent and detect drowsy driving. Be alert. Be safe. Be aware of drowsy driving.

Drowsy Driving Prevention Resource Center

Videos: "Almost Home" and "Recognizing the Drowsy Driver" by National Road Safety Foundation.

Education Materials in English

Materiales de Educación en Español

I. Introduction

Blurry photo of person driving moped

Drowsy driving. It doesn't sound too serious, does it? But like a sleeping giant who wakes up to find an intruder, drowsy driving can be deadly. In fact, it can be just as dangerous as drunk driving. The results in terms of damage, injury, and death can be just as permanent. The risk is obvious when someone falls asleep at the wheel. But the danger begins long before that. Drivers who are tired and sleepy have delayed reactions and make bad decisions. Not only are they putting themselves in danger, but they are a risk to everyone else on the road.

II. What is Drowsiness?

Everyone needs food, water, and sleep to survive. You can choose not to drink water or eat any food. If you do this for a long enough period of time, you can die. This is impossible when it comes to sleep. Your body has such a strong need to sleep that at some point your brain will make you do it. It doesn't matter how hard you resist. It doesn't even matter what you are doing at the time. You must go to sleep.

Several factors can cause you to be drowsy. These include the following:

Your body clock

Your body has an internal clock that tells it when it is time to be asleep and when it is time to be awake. This clock is located in the brain just above an area where the nerves travel to the eyes. This area is called the SCN. Your clock controls the "circadian rhythms" in your body. These rhythms include body temperature, alertness and the daily cycle of many hormones. The word "circadian" means to occur in a cycle of about 24 hours. Circadian rhythms make you feel sleepy or alert at regular times every day. You become sleepy in the evening at bedtime. You also become sleepy again at mid-day. This is when some people like to take a "siesta" nap.

How long you've been awake

Your body needs sleep on a daily basis. The longer you stay awake, the more your body needs to go to sleep. Each person has their own pattern and need for sleep. On average, most adults need seven to eight hours of sleep each night in order to feel well rested. If you are not getting enough sleep, then your body has a sleep debt. This debt continues to grow as you "add on" more and more hours of missed sleep. As you miss more hours of sleep, you will find it harder to think and perform as well as you would like.

When you don't get enough sleep, you lower your level of alertness and performance. You react slower and have added trouble when you try to make decisions. It is much harder to pay attention to what you are doing. Your memory and coordination are also weaker when you are sleepy. People who are drowsy often don't even realize it. This makes being drowsy that much more dangerous. The effects of being drowsy are very much like the effects of drinking alcohol. Studies have shown that losing just a few hours of sleep each night can impair your ability to drive in the same way as drinking too much alcohol.

This fact is made even more disturbing by data showing how much sleep people get on a regular basis. Sleep surveys show that many adults do not get enough sleep to feel well rested. This can cause some people to be drowsy almost every time they get behind the wheel of a car. Others may drive drowsy only at certain times. In both cases, the results can be fatal.

III. How Widespread Is Drowsy Driving?

The U. S. National Highway Traffic Safety Administration (NHTSA) conducts research on driver behavior and traffic safety. They say that drowsy driving is a cause of at least 100,000 auto crashes each year. These crashes hurt an average of 40,000 people and result in over 1,500 deaths. The NHTSA suggests that the actual numbers are much higher. Their figures do not include wrecks that occur during the day. They also do not count crashes that involve more than one vehicle. If these and other factors were added in, the deadly toll of drowsy driving would be far greater. Public surveys have also shown that drowsy driving is a very common danger. In one survey, 55% of those polled said they had driven while drowsy in the past year.

Many of the wrecks that are caused by drowsy driving are not properly counted. This is because it is hard to know for sure when someone is too tired to drive. Drowsy driving is much more difficult to identify than drunk driving. A simple breath test will show if someone has had too much alcohol. There is not a test that clearly shows when someone is too sleepy. Traffic officials are often not trained to look for sleep-related causes at the scene of a crash.

This means that a crash caused by drowsy driving might be said to have been caused by something else. After all, the scene of the crash can look the same as one caused by reckless driving or drunk driving. Many states do not even have a code on their crash report forms to show when a driver fell asleep. They also do not have a central database to track these causes.

There is usually no one who sees a driver falling asleep prior to a crash. Drivers are often alone, or others in the car are already asleep. The drivers themselves don't always realize they are drowsy before they doze off. In fact, drowsy drivers are often more alert after a crash or other mistake. Their body gives them a rush of adrenaline that jolts them awake. This can cause an observer to think that the driver was also alert before the wreck.

When a driver is both drowsy and drunk, the alcohol is often listed as the only cause of a crash. After a wreck, many drivers do not want to tell the police that they were drowsy. All of these factors show why the numbers for drowsy driving are too low. It is clear that drowsy driving is not just a risk. It is a danger that is all too common on the road.

All drivers should learn more about both drowsy driving and their need for sleep. If you can identify the signs of drowsy driving, you will be able to keep from making a critical mistake on the road. Learning more about good sleep habits will also be a big help. You will be able to get the kind of sleep that your body needs. This will make you more alert in the car and everywhere else you go.

IV. What Are The Common Characteristics In Drowsy Driving Accidents?

Late night and mid-day

Data shows that most crashes caused by drowsy driving occur from midnight to 8:00 a.m. It is most natural for your body to go to sleep when it is dark outside. This is why it is so hard for drivers to fight off sleep at night. Your body clock also makes you sleepy in the middle of the day. This is why drowsy driving is a cause of many wrecks from1:00 p.m. to 3:00 p.m. At both of these times of day, your body gets sleepy even when you are well rested. If you must drive during these times, make sure that you get plenty of sleep beforehand.

Single driver

In one study, 82% of drowsy-driving crashes involved someone driving alone. A single driver has no one to talk to who can help keep him alert. Other people in a car will often notice when the driver is getting sleepy. Driving by yourself also means that you must do all the driving. Driving with others allows you to take turns behind the wheel.

No attempt to avoid a crash

In most crashes caused by drowsy driving, the driver does not try to avoid the accident. A lack of skid marks at the scene shows that the driver never hit the brakes. People who see the crash notice that the brake lights did not come on. They also observe that the car did not try to swerve out of the way. A sleepy driver does not react to danger in time. His eyes may even be closed, keeping him from seeing what is about to happen. This often leads to a very brutal wreck. A high rate of drowsy-driving crashes results in death.

V. Who Is Most At Risk?

Young male drivers

Drivers who fall asleep at the wheel are often young men. A person is likely to be sleepy due to his lifestyle or behavior choices. Young men are often more likely to make choices that cause them to be sleepy. These choices include staying up late, working long hours and drinking alcohol. It has also been shown that sleepy people are more likely to engage in high-risk behavior. Young men are also likely to have increased amounts of risk-taking behavior.

Shift workers and business travelers

Those who work at night or on rotating shifts can have a very hard time sleeping. They have to work at night when their bodies want to sleep. Then they have to try to sleep during the day when their bodies want to be awake. This throws their internal body clocks into confusion. Their sleep patterns go against the body's natural pattern of sleeping and waking. This problem can become a circadian rhythm sleep disorder.

Travelers who cross many time zones during a flight have a hard time sleeping in their new locations. Their internal clocks are set to the time of day in a different place. This can become a big sleep problem for pilots and business travelers who must fly long distances all the time.

All of these people can suffer from a lack of sleep, or poor quality of sleep. This can cause them to be severely sleepy and less alert when they need to drive at any time of day.

Drivers who regularly don't get enough sleep

Many people get less than the amount of sleep at night that their bodies need to feel well rested. Their sleep debt grows larger and larger over time. As the debt becomes greater, so does their need to sleep. They become severely sleepy, which hinders their attention and performance in a variety of tasks. They report a high risk of dozing off in many different situations. This is called cumulative partial sleep deprivation. This has a drastic effect on their ability to drive well. They can be in great danger of causing a crash on the road.

Drivers who have been awake for a long period of time

People often have to stay awake for a very long period of time. Students may stay up all night studying for a test. Doctors who are on-call may have to work two shifts in a row. A parent may stay up all night with a sick child. These are all examples of acute sleep deprivation. Your body is not wired to go for such a long time without sleep. This has a serious impact on your ability to pay attention and react while driving. Studies have shown that drivers who have been awake for more than 15 hours are much more likely to cause a crash.

Drivers who have untreated sleep disorders

A sleep disorder that is not treated is likely to keep you from getting enough good sleep. This can cause you to be very tired during the day. Common sleep disorders that cause you to be tired during the day are insomnia, obstructive sleep apnea (OSA), and narcolepsy. More than 12 million people in the U.S. have OSA. Studies show that it creates a large increase in the rate of crashes caused by drowsy driving.

Drivers who use medications that make you drowsy

Many medications found in stores or bought with a prescription can cause you to be very drowsy. These medications have warning labels that describe this side effect. These drugs can greatly hinder even a well-rested driver as he sits behind the wheel.

Examples of the medications that cause drowsiness are:

  • Sleeping pills
  • Narcotic pain pills
  • Some antidepressants
  • Tranquilizers
  • Some high blood-pressure pills
  • Cold or cough tablets/liquids
  • Some anti-histamines (used for allergies)
  • Muscle relaxants

Drivers who have been drinking alcohol

The use of alcohol alone can be enough to cause a car crash. It naturally makes you sleepy and slows your reaction time. When alcohol is combined with severe drowsiness, the dangers are multiplied. Alcohol combined with sleepiness has far worse effects then either of them does alone. They greatly lower mental and physical alertness. This creates more swerving and drifting off the road. One study looked at how well tired people could drive after light drinking. They were given levels of alcohol to drink that were within the legal driving limit. They were then put in a driving simulator. Those with only four hours of sleep made more mistakes than those with eight hours of sleep. The study also found that one beer had the same impact on a person with four hours of sleep as six beers had on a well-rested person.

VI. What Are The Signs Of Drowsy Driving?

Below are a few of the most common signs that a driver is too tired to sit behind the wheel. If you experience any or all of these signs, you may be at risk of causing a car accident.

  • You yawn frequently.
  • You are unable to keep your eyes open.
  • You catch yourself "nodding off" and have trouble keeping your head up.
  • Your thoughts wander and take your focus off the road.
  • You can't remember driving the last few miles.
  • You are impatient, in a hurry, and grouchy.
  • You end up too close to cars in front of you.
  • You miss road signs or drive past your turn.
  • You drift into the other lane or onto the shoulder of the road.

VII. How Do We Prevent Drowsy Driving?


The three best ways to prevent drowsy driving involve behavior choices. First, make sure you get a good night's sleep before driving. Sadly, most people don't think about the effects of failing to get enough sleep until it is too late. Getting up extra early in the morning to start a long driving trip is not a good strategy. Neither is driving overnight when your body would usually be sleeping. Prevention is the best way to avoid drowsy driving. For that, there is no substitute for sleep. Making it a habit to get a good night's sleep is the best protection against drowsy driving.

The second way to prevent drowsy driving is to pull off the road and get some sleep when you are feeling tired. You should do this even if you think your driving ability is not being affected. Many people think they can overcome being drowsy as they are driving. They don't always realize how much less alert they are. They can have no idea how close they really are to causing a crash. Even if you are only starting to feel sleepy while driving, be safe and pull over. At the very least, take a short nap to rest your eyes. This will go a long way toward keeping you safe.

Third, it is also wise for drivers to avoid alcohol and medications that can make them tired. Be very careful. Never get behind the wheel of a car after you have had any alcohol to drink. Also be aware that a medicine can still affect you even hours after you have taken it. Talk to your doctor about any medications you take. Make sure that you know for certain if they can hurt your ability to drive.


The use of caffeine can give a short-term boost to help you be more alert. It is a good idea to take a short nap after drinking some coffee or cola. The nap gives you some rest, and it also gives the caffeine time to get in your system. While caffeine helps, it does not overcome the effects of being drowsy. The boost that it gives you also wears off. Caffeine should not be seen as a way to replace sleep.

Alerting devices

One of the best devices to help alert drivers when they are getting sleepy is the "rumble strip" on the side of many roads. This road border is made up of a pattern of deep grooves. A car that drifts onto the rumble strip begins to vibrate and make a loud groaning noise. This is meant to wake up a driver who does not realize that he is losing control of the car. Although rumble strips are helpful, they do not solve the problem of drowsy driving. Many drivers are just as likely to drift into another lane of traffic as they are to go off the road.

Some auto makers have been working on devices that would be put inside cars to keep drivers alert. These devices would keep track of how sleepy a driver is. Some models would use an alarm to wake the driver. There is still not enough data, however, to prove that these devices really work. Also, an alarm only reveals a problem. It does not solve the problem. Alerting devices do not help drowsy drivers get more sleep. These devices could even give drowsy drivers a false sense of security. They may think that it is safe to drive while drowsy, trusting these devices to keep them awake.

Shift work & jet lag

Many employers have plans to help their shift workers stay better rested. The goal is to lessen the effects of shift work on the workers' body clocks. This keeps them healthier overall, as well as safer on the job and on the road. Some of the techniques used by employers include the following:

  • Reducing the number of times a worker changes shifts
  • Changing shifts forward in time instead of backward
  • Giving the workers regular rest periods
  • Offering employees the option of exercise breaks
  • Using bright light to imitate sunlight

Travelers who are trying to avoid jet lag should plan ahead. They can slowly adjust the times that they go to sleep and wake up before they go on the trip. When the time for their trip comes, their schedule of sleeping and waking should be close to what it will be in their new location. Rest periods, exercise, and the use of bright light can also help you overcome the effects of jet lag.

Awareness of medical disorders

Some drowsy drivers may actually suffer from untreated sleep disorders. The most common are insomnia, obstructive sleep apnea (OSA) and narcolepsy. People with insomnia can rarely get a good night's sleep. They tend to feel tired and grumpy on a daily basis.

People who have OSA usually snore loudly, gasp for air while they sleep, and have brief pauses in their breathing. When they stop breathing, their bodies wake up. It happens so quickly, they aren't even aware of it. This disrupts their sleep process and keeps them from feeling refreshed from their sleep. They can stop breathing hundreds of times in one night. This will make them feel very tired the next day.

Narcolepsy can cause someone to fall asleep suddenly in almost any situation at any time throughout the day. If you think that you have any of these disorders, you should see a sleep specialist for proper treatment.

VIII. Good Sleep Habits

Avoiding drowsy driving begins with the practice of good sleep hygiene. Sleep hygiene consists of basic habits and tips that help you develop a pattern of healthy sleep. See the Resources section of this site to find out how you can start down the path to better sleep.

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