minimum amount of required sleep before long drive
Sleep Safety

How Much Sleep Do You Need to Drive a Car Safely?

Last Updated on February 12, 2024 by Louise Carter

According to the Foundation for Traffic Safety (FTT), 45% of Americans admitted to driving when tired. Given that drowsiness and drunkenness affect the brain in similar ways, this is a worrying statistic.

Long commutes, irregular shift patterns, and busy social lives may be responsible. Many of us feel under pressure to get from A to B as quickly as possible, no matter how tired we feel.

Sleep Requirements for Safe Driving

According to the U.S. Department of Transportation, the only way to ensure safe driving is to get 7-8 hours of quality sleep each night. If you want to drive safely, you’ll need to be aware of:

  • The signs of drowsiness can be difficult to recognize, so stay vigilant.
  • Certain groups (truck drivers, teenagers, people with sleep disorders, etc.) are more susceptible to falling asleep at the wheel.
  • Tiredness is sometimes unavoidable. If you’re nodding off at the wheel and there’s nowhere safe to stop, there are ways to perk yourself up until you can rest.
  • Drowsy-driving laws vary from state to state. Non-government campaigners play an active role in reducing drowsy-driving crashes, so note their recommendations.

Why Is Sleep Important for Driving?

Here’s how sleep can help us become safer drivers:

  • Reaction times – Studies have shown that sleep-deprived individuals take longer to make decisions. In addition, people with less sleep make poorer judgments when rushed.
  • Concentration – Our attention span lengthens when we’re well-rested. If you’ve been driving for a few hours, concentrate on road signs, traffic signals, and other drivers.
  • Mood – If you’ve had 8 hours of sleep, you’re less likely to lose your temper with fellow road users or backseat drivers. Outward displays of road rage can lead to crashes and collisions.
  • Spatial memory – This is important for learning road routes. Sleeping for 6-8 hours (undisturbed) helps to improve our spatial memory.
  • Procedural memory – This is your memory for ‘tasks.’ If you’re learning to drive or getting used to driving a new vehicle, sleep will help you learn faster. Procedural memories are rehearsed during the REM stages of sleep, and the highest quality REM stages occur after 6 hours of sleep.

Is Drowsy Driving A Big Problem?

According to the NHSTA, 100,000 crashes reported to the U.S. police involved a drowsy driver. 3,000 died, and 76,000 were injured in drowsy driving-related motor crashes.

Unfortunately, many motorists are unaware of the risks of drowsy driving because crashes are sometimes misreported, as drowsiness can be hard to prove.

Thankfully, there are many things you can do to stop yourself from falling asleep at the wheel.

Signs of Falling Asleep At The Wheel

Drowsiness can be hard to recognize, as we can’t predict sleep when we’re tired at the wheel. Fatigue can creep up on us, and we may not realize it until it’s too late.

If you experience the following symptoms when driving, act immediately:

  • Frequent yawning.
  • Heavy and itchy eyes.
  • Blurred vision and an inability to read road signs.
  • Irritability and short temper.
  • Inability to drive in a straight line.
  • Head and neck starting to droop (head nodding).
  • Microsleeps, which involve dozing off for 2-3 seconds.

Symptoms like these should never be ignored.

driving fatigue symptoms

Why Are Microsleeps So Dangerous?

During microsleeps, our brainwaves change from an alpha state to a theta state. In other words, brain activity slows down considerably. During a microsleep, we become unaware of our surroundings.

Imagine traveling along the highway at 70 mph, and you fall asleep for 5 seconds. This means you’d travel 157.5 meters blind. Added to this, microsleeps can last for up to 30 seconds.

Perhaps the most dangerous thing about microsleeps is our inability to recognize them.

Most of the time, you won’t even know you’ve had a microsleep. This is worrying because it stops you from intervening and taking some much-needed rest.

Even if microsleeps don’t immediately lead to a collision, consecutive microsleeps will impair your judgment. Studies have shown that having several microsleeps leads to confusion and distress.

Tasks like giving way, changing lanes, or slowing down are more difficult following microsleeps.

How To Be More Alert While Driving

If you’re feeling weary at the wheel, the ideal thing to do is stop your car and sleep for 8 hours. However, stopping your vehicle may be unsafe on a busy highway.

If you find yourself in this situation, consider the following short short-term solutions:

  • Open the car windows and allow some fresh air to circulate.
  • Turn the radio on and play some upbeat music.
  • Ask a passenger to talk to you.

Of course, for this to work, the passenger must avoid falling asleep.

Napping

According to the NHTSA, you should look for a designated resting place and nap when tired. Naps should last 45 minutes, but a 10-20-minute nap will be beneficial.

Studies have shown that napping can increase alertness for 2-3 hours.

When you wake up from your nap, wait 5-10 minutes before driving off. This will ensure you’re fully awake and ready to face the rest of your journey.

Caffeinated Drinks

According to the Transportation Research Board, caffeine helps sleep-deprived drivers maintain the correct speed and stay in the right lane during a driving simulation.

In this study, the drivers were given 4 x 200 mg of coffee over 24 hours (200 mg is equivalent to one strong cup of coffee).

The NHTSA recommends drivers pull over and drink 1-2 cups of coffee when sleepy. Drivers should rest for 15 minutes before driving off to allow the effects of caffeine to take hold.

Caffeine is a short-term solution. Limit your intake to 4 cups of strong coffee per 24 hours because too much coffee can make it difficult to recognize microsleeps.

How To Prevent Drowsy Driving

Did you know that sleeping for only 4 hours increases the risk of having a crash by 11.5 times?

If you work long night shifts or are used to grabbing sleep whenever you can, you’re likely skeptical about sleeping for 8 hours.

Try some of these tips to see if they make a difference:

Good Sleep Hygiene

Go to bed at the same time each night to establish a healthy sleep routine. Aim for 7-8 hours of sleep per night, so set your bedtime accordingly.

Make your bedroom as dark as possible to encourage melatonin production, and keep electronics out of the bedroom to avoid overstimulating the brain. There are alternatives to watching TV.

Sleep Comfort

Don’t underestimate the importance of comfort when getting a good night’s sleep. Choose a quality mattress and pillows to relax.

Healthy Diet

A study by the FMCSA found that CMV drivers who had crashed due to drowsiness often had poor diets. Indeed, sleep deprivation can lead to overeating because it interferes with appetite regulation.

Eat regular, balanced meals to avoid fluctuating hunger levels. Also, avoid eating heavy meals before bedtime as this can disturb sleep. Certain sleep positions can aid digestion.

Working Hours

Many of us take on regular overtime to pay the bills. Not only truck and taxi drivers suffer drowsiness at the wheel. It can apply to any overworked person who drives as part of their commute.

Manage your workload and ensure you follow the employer’s policy for fatigue prevention.

Hydration

Keep a bottle of water and drink regularly to stay hydrated. That way, it’ll be easier to focus on the road.

Drowsy Meds

The FMCSA found that 17% of drivers involved in crashes had taken over-the-counter drowsy medications in the 12 hours before the crash. OTC cold, flu, and hay fever medicines make you feel drowsy.

Avoid driving when you have the flu, as influenza can slow down your reflexes. If you have a light cold or hay fever, choose non-drowsy medications if you’ll be driving.

Share Driving Responsibilities

If you’re going on a long road trip, share the driving with a friend or family member.

Plan Your Route

Plan your route so you can schedule rest breaks. This will take the stress out of your journey so you can concentrate on driving.

When to Take Extra Care While Driving

Certain factors can make drowsy-driving crashes more likely, including:

Driving on the Freeway

Crashes caused by tired drivers are more likely to occur on the freeway because the driver lacks stimulation and is overly relaxed.

If your journey incorporates long and boring roads, play some of your favorite music or listen to an interesting radio program to keep your mind focused.

Naturally Occurring Lulls

Our sleep/wake cycle operates based on a 24-hour clock (circadian rhythms). At specific points in this cycle, our energy levels plummet.

Our energy levels are known to dip at the following times:

  • 12 AM – 6 AM.
  • 2 PM – 4 PM.

Studies have shown that crashes caused by drowsy drivers are more likely to happen during these hours. If you’re driving a long distance, schedule rest breaks at these times.

If you drive at these times, drink a cup of coffee and be vigilant about the symptoms of drowsiness.

Sleep Inertia

Crashes are more likely to occur during the first hour of driving, which could be because the driver hasn’t allowed themselves sufficient time to wake up from sleep.

Truck drivers who sleep in their berths are most at risk of this phenomenon, as they’re more job-focused and less likely to allow themselves time to wake up slowly.

Truck Drivers And Drowsy Driving

According to the Department of Health and Human Services, truck drivers should get 8-9 hours of sleep.

If you’re a long-distance driver, consider the following tips:

  • Tell friends and family – If friends and family know how crucial your sleep is, they’re less likely to disturb you. We’re likelier to make positive behavioral changes with the support of our family.
  • Stress relief – Being a driver can be stressful and isolating. Find ways to relieve stress during your time off, but avoid stimulants like nicotine and energy drinks.
  • Prevention naps – According to the FMCSA, napping is more effective before you feel tired. If you regularly drive long distances, schedule naps into your journey.
  • Sleeping on the road – Pick a safe spot to park that’s still reasonably quiet. Ensure the temperature of the berth is conducive to sleep, and consider buying a good-quality pillow to feel more comfortable. Also, put a blue filter on your phone if you keep it close to your bed.

Teenagers And Drowsy Driving

Teenagers’ brains are still developing, so their sleep requirements are greater than those of adults. Teenagers should regularly sleep for 7-9.5 hours per night.

At the same time, teenagers often stay up late and pull all-nighters, which makes them particularly susceptible to becoming tired at the wheel.

Teenagers are inexperienced drivers. Sleep will enable them to become better drivers because good quality REM sleep strengthens procedural and spatial memory skills.

They’re more likely to be hesitant drivers if they miss their sleep.

Sleep Disorders And Drowsy Driving

The American Sleep Association estimates that up to 70 million Americans suffer from chronic sleep disorders. The most prevalent sleep disorders that directly affect a person’s ability to drive are sleep apnea, narcolepsy, and insomnia.

Regulations regarding driving with narcolepsy vary from state to state. In most states, a doctor must contact the DMV if you have a condition that may cause a loss of consciousness.

The FMCSA stated that a person might not be qualified to hold a commercial driving license if a condition affects their ability to operate safely.

Drowsy Driving vs. Drunk Driving

Feeling very sleepy can be as dangerous as feeling drunk. The cognitive effects of being drunk (poor coordination, slower judgments) are similar to those of being tired.

According to NCBI, after 17 hours of no sleep, cognitive performance is comparable to having a blood alcohol volume (BAC) of 0.05.

After 24 hours of no sleep, your brain responses indicate a BAC of 0.10. Most U.S. states set their BAC levels at 0.08, so you’re over the legal limit if you drive after being awake for 24 hours.

After 36-48 hours of no sleep, you’ll likely experience hallucinations, severe memory loss, and regular microsleep. It would be risky to drive in these conditions.

is it illegal to drive while sleep-deprived?

Is It Illegal to Drive While Tired?

The law regarding fatigued driving varies from state to state. Arkansas and New Jersey are the only states to legislate against drowsy driving.

Maggie’s Law – New Jersey

Named after Maggie McDonnell, a sleep-deprived driver killed in a 1997 crash, New Jersey’s ‘Maggie’s Law’ (National Driving Act of 2003) was the first U.S. law to target drivers who haven’t slept for 24 hours.

Under Maggie’s Law, drivers found to have caused death due to sleep-deprived driving may be prosecuted for vehicular homicide, carrying a maximum sentence of 10 years imprisonment and up to a $100,000 fine.

The law has been difficult to enforce, with only 2 convictions since its enactment in 2003.

Negligent Homicide – Arkansas

Arkansas made drowsy driving an offense under 2013 negligent homicide laws. The change in law classed fatigued driving as a Class B felony.

If a driver is convicted of causing death due to driving while tired, they could be imprisoned for up to 20 years and be fined up to $15,000.

Just 3 people have been convicted since this law came into effect.

What Is Being Done to Reduce Accidents?

Although laws have been difficult to implement, charities, employers, and local governments are working to reduce the number of drowsy-driving road accidents.

Rumble Strips

Crashes caused by sleep deprivation are often roll-off-the-road crashes. An effective countermeasure to this type of crash is the installation of rumble strips along the edges of roads.

These rumble strips are patterns in the tarmac that, when driven over, cause vibrations, alerting the driver that they’re leaving the highway.

In specific locations in New York, rumble strips reduced roll-off-the-road incidences by 84%.

Drowsy Driving Awareness

Each November, the National Sleep Foundation holds Drowsy Driving Prevention Week to raise awareness of the dangers of driving while insufficiently rested.

The foundation releases facts and figures about drowsy driving and educates people on the risks of driving without sufficient sleep. Also, some states have awareness initiatives.

Alabama and California have drowsy driver awareness days (November 19th and April 6th, respectively), and Florida and Texas promote drowsy driver awareness weeks in September and November.

Employer Responsibility

To reduce sleep-related accidents, employers must play their part.

Driving-related industries like trucking companies, couriers, and taxi firms are responsible for abiding by national legislation regarding working hours.

Uber introduced new policies stipulating drivers must rest at least 6 hours following 12 hours of work.

Individual employers have limited control over people who work multiple jobs, so employees must share some of the responsibility.

For the most part, tiredness is a personal complaint. When you get behind the wheel of a car, your tiredness could affect other road users.

For this reason, you need to take drowsiness as seriously as other cognitive impairments, such as driving under the influence. Concentration, judgment skills, and reflexes are significantly impaired when tired.

To be a safe driver, you must regularly get 6-8 hours of sleep. If you drive as part of your job or are a teenage driver, get 8-9 hours of sleep.

Remember, if you need to fight fatigue, use caffeine, naps, and music to perk you up.