Drowsy Driving vs Drunk Driving: What's The Difference?

Written by
Purple Staff
Last Updated
July 29, 2022
min read

Everyone knows how dangerous drunk driving is. According to the National Highway Traffic Safety Administration (NHTSA), as many as 28 people die from alcohol-impaired collisions in the US on a daily basis. To put that into perspective, that is one death every 52 minutes. 

However, what a lot of people fail to realize is that it is just as dangerous to drive while fatigued. In 2017 alone, the NHTSA reported 795 deaths caused by drowsy driving accidents. On top of that, there were a reported 50,000 injuries as a result of the 91,000 car crashes just in the span of that one year.

Keep reading to find out more about drowsy driving, why it’s dangerous, and how to stay safe on the road.

What Is Drowsy Driving?

Drowsy driving is when you are too sleepy or tired to properly operate a vehicle. Typically, this happens when the driver doesn’t get enough hours of sleep or is exhausted to the point of driver fatigue. While these are the more common causes of drowsy driving crashes, other causes could also be an untreated sleep disorder, medication, or shift work.

Drowsy driving is actually more common than you think. In the last year alone, as many as 20% of people have fallen asleep at the wheel, according to the CDC – that’s 1 in 25 drivers.

Why Is It Dangerous To Drive When You're Tired?

A lack of sleep can drastically affect reaction times, attention span, coordination, and judgment. These abilities are all absolutely crucial when operating a motor vehicle. 

Much like drunk drivers, fatigued drivers may have trouble steering in a straight line causing the vehicle to weave between lanes. This, of course, puts you at risk of crashing into something, or worse, another vehicle.

Risk Factors For Drowsy Driving

Below are several risk factors that will make you more likely to drive drowsy. Having more than one compounds the risk even further:

  • You did not get enough sleep.
  • You’ve taken a sedative.
  • You have an untreated sleeping disorder.
  • You have a particularly long shift and/or work the night shift.

What Is Drunk Driving?

Drunk driving is when a person operates a motor vehicle while under the influence of alcohol. Legally speaking, in the US, you could be found guilty of drunk reckless driving if your blood alcohol level reaches 0.08%. 

The average body weight of a man in the US is about 200lbs, which means that it would only take four beers to reach that blood alcohol level. However, you don’t need to reach that level to already feel the effects of alcohol in your system.

According to the NHTSA, 2017 saw as many as 9,949 alcohol-related car crashes, comprising nearly 30% of all fatal crashes.

Why Is It Dangerous To Drive When You've Drank Alcohol?

Operating a motor vehicle while drunk increases the likelihood of reckless driving and could make you and other vehicles around you a crash risk. 

It only takes about 30 minutes to two hours before alcohol is absorbed into the bloodstream. Once this happens, your cognitive skills will start to slow down and your driving performance will suffer. Your judgment is hindered, so you might drive at an abnormal or sudden speed.

Risk Factors for Drunk Driving

Below are several risk factors that will make you more likely to drive drunk. A combination of them increases the risk even further:

  • How much alcohol you have drunk relative to age, body weight, and gender
  • Having been previously convicted of driving while impaired
  • Mixing alcohol with certain types of medication
  • Having a substance abuse problem

Drowsy Driving vs Drunk Driving

The main difference between drowsy driving and drunk driving is what is impairing your skills as a driver. Drowsy driving happens when you haven’t gotten enough sleep, while drunk driving happens when you’ve had too much to drink. However, regardless of the cause, its effects on your body and the potential resulting consequences are almost identical.

While there is more stigma surrounding drunk driving, drowsy driving is just as dangerous. There is quite a huge overlap between the effects of the two.

What Are The Similarities Between Drowsy Driving And Drunk Driving?

Both drunk and drowsy driving can greatly hamper your cognitive and motor skills, resulting in reckless driving. According to the CDC, if you have been awake for 18 hours straight, your driving abilities will be similar to someone with a blood alcohol content (BAC) of 0.05%. 

For context, you can get arrested for a DUI if you drive with a blood-alcohol level of 0.08%. If you’ve been awake for a whole 24 hours, it is equal to having a BAC of 0.10% which is well over the legal limit. Additionally, consuming even a small amount of alcohol can have a stronger effect on you if you’re already drowsy.

If you have a substance abuse problem, you are also likely not getting enough sleep. Studies have shown that people who struggle with substance abuse are also more likely to have a sleep disorder. This drastically increases the risk of combining drowsy and drunk driving. 

It’s important to seek help to manage addiction and avoid the consequences of sleep deprivation.

How To Stay Safe On The Road

There are many ways to prevent driving drunk or drowsy. The more mindful you are of these measures, the more you reduce your risk of getting into a road accident.

Ways To Prevent Drowsy Driving

  • Get adequate sleep: The American Academy of Sleep Medicine says that adults require about seven to eight hours of sleep every night to feel well-rested. Practice good sleep hygiene to meet these hours and avoid suffering from sleep deprivation.
  • Be conscious of your energy levels while driving: Ideally, you should avoid driving altogether if you’re feeling tired. However, the feeling of fatigue may come suddenly, especially if you’re in the middle of a long drive. Suddenly feeling heavy eyelids is one of the easiest effects of fatigue to spot while driving. If this happens, consider pulling over to a safe spot and sleeping for 20-30 minutes.
  • Plan your drives accordingly: Avoid making plans that require you to start your journey tired or during sleepiness periods. For example, if you have long night shifts or know you’re going to be jet-lagged, have a reasonable period of rest between your activities and ride.

Ways To Prevent Drunk Driving

  • Assign a designated driver when out drinking: Designate a responsible driver who won’t be drinking while you are out. It’s important to nominate this person ahead of time instead of assuming someone will pick up the role later, when the levels of alcohol intoxication within your group are already high.
  • Get a taxi or rideshare instead: Even if you own your own vehicle, consider paying for a taxi or rideshare instead, especially if you know you’re going to be out drinking.
  • Hold your friends and family accountable: Be mindful of your friends and family’s level of intoxication. Discourage them from drinking too much, and take away their keys if they insist on driving while drunk.
  • Host responsibly: When hosting a gathering, make sure your friends or family don’t drive when they’ve had too many drinks. Offer a non-alcohol drink option, like juice or a caffeinated beverage, so there is an alternative to alcohol.

Frequently Asked Questions On Drowsy Driving vs Drunk Driving

Is being tired like being drunk?

The number of road accidents caused by tired drivers is comparable to drunk drivers. This is because the way your brain operates on alcohol is highly similar to how it does when it is fatigued.

Is driving drowsy impaired driving?

Driving drowsy counts as impaired driving. If you’ve had poor sleep, your cognitive and motor abilities become impaired and you risk causing a road accident.

What type of driver is most likely to be at risk of drowsy driving?

People at risk of drowsy driving are those who have an irregular sleep schedule. This can be caused by voluntary behavior encouraged by unhealthy sleep hygiene, medication, medical conditions, untreated sleeping disorders, or even something as simple as working long shifts.