Is It Safe To Sleep in a Car With the Engine Off?

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When thinking about sleeping in your car, one of the biggest concerns that you should have is carbon monoxide poisoning. Carbon monoxide is a deadly gas that’s produced by your car’s engine, and the easiest way to prevent carbon monoxide poisoning from occurring is by turning your car’s engine off before you go to sleep. However, is it safe to sleep in a car with the engine off?

If you take the proper precautions, sleeping in a car with the engine off is safe. It’s crucial to ensure that you’re in a safe, monitored area, designated rest areas being the preferred option, and that the weather is safe before you do so.

The rest of this article will go over all the ways that you can make sure you’re keeping yourself safe while you’re sleeping in a car with the engine off.

Engine-On vs Engine-Off to Sleep in your Car

It’s always best to sleep with the engine off when it comes to sleeping in your car. Sleeping with the engine on could result in carbon monoxide poisoning, which can be fatal.

Of course, there are some situations where it might be impossible to sleep with your car engine off. If it’s very cold or hot, you may need to use your air conditioning and heating system. However, if possible, it’s best to turn the engine off before you go to sleep.

Carbon monoxide can get into the car because of a faulty exhaust system or other cars nearby in an enclosed space. This is why there have been fatal cases of carbon monoxide poisoning in people’s garages. 

If the fumes have nowhere to go, they can build up and kill you. If they build up in your car while you’re sleeping in it, then chances are you won’t notice any symptoms, and the incident will prove fatal. 

The symptoms of carbon monoxide poisoning are apparent while you’re awake, they include:

  • Vomiting
  • Dizziness
  • Headache
  • Weakness

But if you fall asleep, you may not notice them. 

One of the effects of carbon monoxide is that it almost acts as a sort of sedative, and if you breathe enough in, you’ll pass out. If you’re already asleep, then chances are you won’t notice the symptoms and will end up breathing in enough that it becomes fatal.

Related Articles:
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Is There Enough Air In a Parked Car?

There is enough air in a parked car with the engine off. Cars aren’t airtight vehicles, and the same vents that pump your air conditioning will also be open to the outside air. Although running out of air is a common concern, there’s no real risk of this happening.

There are thousands of liters of air in your car, and when we breathe, we only use about a quarter of the oxygen in the air. 

Even if your vehicle was airtight, this would leave you with enough air to breathe for several hours. Plus, as I previously stated, cars aren’t airtight, so you’ll always have some fresh air coming in and out of your car, making running out of oxygen virtually impossible.

Park in a Safe Area to spend the night

If you’re choosing to sleep in a car, with the engine on or off, one of the biggest things you should be considering is your safety. 

Sleeping in your vehicle with the engine turned off can make you seem like more of a target to those who may want to rob your car. In these cases, one of the best things you can do is choose to park in a designated rest area or DRA. 

Designated rest areas are located all along most major highways. They’re monitored by cameras and security and typically have lots of drivers sleeping there for the night, which might help to deter criminals. 

In addition to sleeping in a DRA, there are a few other things you can do to keep yourself safer. You’ll need to make sure you park in a well-lit area, which will deter criminals because it’s harder to escape the view of any camera if there’s a lot of light. 

You’ll also want to try to park your car up against a tree, wall, light pole, or other strong structure. This will make it so that any potential robbers have a more difficult time opening your door.

Related Article:
How To Sleep in a Car Without the Alarm Going Off

Temperature Concerns when sleeping in your car

One of the main reasons people want to keep their car engine on is temperature concerns. Of course, you always hear that you shouldn’t leave your dog in a parked car without air conditioning, so you shouldn’t leave yourself in one either, right?

If the climate is particularly hot or cold, sleeping in your car may not be a good option. 

For safety reasons, you need to have some way to control the temperature in the vehicle. You’ll either have to leave the windows down or keep the car running, neither of which are good options.

Cars can very quickly heat up to high temperatures or drop to below freezing very quickly. That makes sleeping in your car a dangerous option if you’re dealing with any sort of extreme weather. To keep yourself safe, you’ll either have to leave your windows down, if it’s hot, or keep your car running.

Keeping your car’s engine on has its own set of risks that we’ve already discussed. By doing so, you’re making yourself vulnerable to carbon monoxide poisoning, which can be fatal. 

If you choose to leave your windows down, you’ll also run into issues. First of all, if you’re in direct sunlight, then leaving the windows down may not do much to help you cool down. Even more importantly, leaving your windows down leaves you vulnerable to being assaulted or robbed. 

If you choose to do this, make sure you’re in a well-lit, protected area.

Related Article: Is It Safe to Sleep in Your Car in the Winter?


If you want to sleep in your car with the engine off, it can be a perfectly safe option if you take the proper precautions. These include parking in a well-lit, monitored area, keeping your windows closed, and parking by an object that’ll help prevent your door from being forced open.

Remember, there’s no risk of you running out of oxygen as cars aren’t air-tight. 

The biggest thing that you’ll have to worry about is avoiding crime and maintaining safe temperatures, both of which can be done easily with enough planning.

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