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Is it safe to sleep in a car?

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Sometimes you may need to spend a night in your vehicle. This decision should not be taken lightly and if you have any concerns you should always book a room in a hotel. This article will answer all the questions you have so that you can make a reasoned decision.

Is it safe to sleep in a car?

It is generally safe to sleep in your car overnight, provided the engine is turned off and you’re parked in a secure location. Cars are not airtight, meaning oxygen can enter the vehicle during the night to allow comfortable breathing, even when the windows and doors are closed. Turn off the AC while sleeping due to risks relating to leaky exhaust systems.

It is not dangerous to sleep in your car if you ensure that the engine is turned off, you’re parked in a safe location, and you’ve brought adequate warm bedding. Do not use the AC while sleeping and ensure you have a fully charged mobile phone in case of emergencies. Opening the window slightly is OK, but not required for fresh air to circulate.

If you need to, use the AC to cool down your car first, ensuring you turn it off before sleeping. You can also heat up your car prior to sleeping, provided you turn off the engine afterwards. Cracking a window open to allow fresh air in is OK, but not required for safe breathing as outlined above.

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Is it safe to sleep in a car with the engine running?

No, it’s not safe to sleep in your car with the engine running. Leaving your car engine turned on while sleeping could lead to dangerous exhaust fumes containing carbon monoxide entering the vehicle. Carbon monoxide is an odourless and colourless poisonous, gas emitted from the exhaust system, which can build up dangerously quickly in enclosed spaces.

Is it safe to sleep in a car with the windows up?

It is safe to sleep in the car with the windows up because fresh oxygen will continue to enter the vehicle. It’s also safer to sleep at night with the windows up to alleviate security concerns. If sleeping in hotter climates, you may want to open a window slightly to all cooler air to circulate. Never open the windows more than a crack.

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Can you sleep in your car with the AC running?

No, you should not sleep in the car with the AC running.  Sleeping with the AC on, even for a short period of time, can be dangerous due to the risk of a leaky exhaust system. This could result in poisonous carbon monoxide gas entering the vehicle. This gas could easily build up without you knowing with dangerous consequences for your health.

Can you sleep in your car with the engine off?

Yes, you can sleep in the car with your engine off. Air can be exchanged through a car’s chassis, so you will have fresh air available to breathe. Unlike when the engine is switched on, carbon monoxide poisoning is not a risk when the engine is switched off. Make sure you take precautions to ensure you are situated in a safe parking location.

Will I suffocate if I sleep in a car?

Cars are not airtight, therefore you will not suffocate if you sleep in your car. A car’s chassis enables air to permeate through, meaning Carbon Dioxide can escape and fresh Oxygen can enter. This transfer of air means you will not suffocate, but you must make sure the engine is off. This remains true even if all windows and doors are closed.

Can you run out of oxygen while sleeping in a car?

You will not run out of oxygen sleeping in a car with the windows closed and the engine turned off. This is because cars are not airtight. Research has also shown that air refreshes naturally in a car every 1-3 hours. A car would have to be full of around 8-9 people before oxygen levels could become compromised.

Do you have to crack a window when sleeping in your car?

No, you don’t need to crack a window open when sleeping in your car.  Air can flow through a car’s body even when doors and windows are closed. This means that fresh oxygen can continue to enter throughout the night. If you’re sleeping in warmer temperatures then you may open a window slightly to allow cooler air in, but never open it more than a crack.

Is it safe to sleep in a car in the garage?

It is safe to sleep in a car in the garage provided the engine is turned off and fresh air can enter easily. Ensure your garage is not airtight before choosing to sleep inside. Take extra care when getting in and out of your vehicle to avoid hazards such as sharp objects or harmful materials. Insulate your car to stay warm overnight.

Where is it safe to sleep in your car?

Finding a safe place to sleep in your car involves using your judgement to carefully access your surroundings. Look for well-lit areas away from moving traffic. Before sleeping, make sure your car is locked and windows are only open a crack at most. Make sure to check you are sleeping in a legal location too by paying attention to street signs. We have a full article outlining 19 Places You Can Sleep In Your Car, which may be of benefit to you.

We also recommend using the Ioverlander app to find safe and legal spots to sleep, as suggested by fellow car campers.

How To Stay Safe While Sleeping In Your Car

We’ve pulled together some top tips and handy sleeping hacks to help you achieve restful sleep. We hope you’ll feel recharged and ready for the rest of your road trip adventures.

1. Find a safe parking location

Is it a safe spot? Are you parked out of the way of moving vehicles? Is it a well-lit area? Are you on level ground and is your vehicle locked?  Where are the nearest restrooms? These are the key questions you need to ask yourself before choosing an overnight parking location.

2. Use an app to find secure parking spots

We recommend using the Ioverlander app to find the best free recommended spots to park up and camp. It’s the best way to avoid any nasty fines and will help you find the safest spots. Some locations can be breathtaking!

3. Park at Walmart

If you’re stuck finding a place to sleep overnight, (and in the US or Canada) find a Walmart. Most (but not all) Walmarts let you park overnight free of charge, with easy access to food and facilities in the morning. If RVs are parked up then it’s a fairly sure sign you can sleep there free and legally.

Check out our article to discover what stores allow overnight parking! If you can’t find a store to park out, check out our article to see whether you can park at a Hospital overnight.

4. Ensure the exterior of your vehicle is as discreet as possible

If you have a rack with a bike or other equipment attached to the exterior of your vehicle then place it inside if you can. You don’t want anything that looks too tempting for thieves to be visible.

5. Use privacy curtains and a car windshield sunshade

Want to keep the morning light or reduce the impact of any street lights? Consider buying a car windshield sunshade and some privacy curtains. They’re a low-cost option to keep light out and importantly give you some privacy too. For a makeshift alternative, bungee cords and a cut-up bed sheet can work too.

6. Insulate your vehicle and take a sleeping bag to keep warm

If you’re sleeping through the night during colder seasons, a good sleeping bag is an essential piece of equipment. Consider gloves and a hat to keep your extremities covered. It’s really important to stay warm overnight while sleeping in a car.

7. Make sure your phone is charged in case of emergencies

Make sure your electronics are charged. You might feel like sending a quick message to a friend or family member before falling asleep. Have your portable battery charging pack too.

8. Tell someone where you are

It’s important to tell a family member or friend where you are and what you’re planning to do. Schedule a time in the morning when you will text or call to let them know you are OK.

9. Use earplugs for uninterrupted sleep

Ear plugs and eye masks could be handy purchases if you want the best chance of having uninterrupted sleep.

10. Be prepared with the correct gear

Keep a bag of toiletries handy; wet wipes can be a useful way to get a quick refresh in the morning before you head on your way.

11. Start the morning with a fresh cup of coffee

If you’re anything like me and in need of a fresh coffee from the minute you wake up. An AeroPress is your go-to option for the tastiest coffee on the road.

Disclosure: Some of the links in this article may be affiliate links. This means I earn a commission if you make a qualifying purchase, but this is at no additional cost to you. Thank you for supporting The Road Trip Expert.

Image of Iain The Founder Of The Road Trip Expert

Iain Salter

Founder & Editor of The Road Trip Expert

Iain founded The Road Trip Expert in 2019 and continues to manage the website to this day. The inspiration to start the blog came during an extensive road trip around Europe with two friends that spanned several months and involved over 25,000km of driving. He first developed a passion for backpacking in 2014 and has had the pleasure of exploring over 60 countries.