How to Sleep in a Car

How to Sleep in a Car

By Glenn Campbell

Note: This article is about how to sleep in a car. See separate article for Where to Sleep in a Car 

If you can sleep in a car, you've gained an enormously valuable life skill. Think about it: You can sleep in places where you can't otherwise afford to stay; you're protected from the elements, and the rent is free (provided the car is already paid for). Even if you don't actually sleep in a car, knowing that you can do it means that you can arrive in a new city without a hotel reservation, just a car rental reservation. If you can't find affordable lodging, you know you'll get by. [Text in red are new revisions as on 8/51/13, after I have been sleeping in cars off and on for years.] 

Sleeping in a car is a form of "car camping," where you sleep in or near your vehicle (as distinct from backpacking—See Wikipedia). In terms of protection from the elements, a car is about halfway between a hotel room and camping in a tent, and if you just need some sleep it's probably easier than both. (There's no tent to set up and no check-in process to go through.) For example, if you are on a long road trip and just need a few hours of shuteye, checking into a motel may be unnecessarily complicated and rob you of still more sleep during the process of finding a room and moving in. Sleeping in the car may be just the thing!

Sleeping in a car may seem uncomfortable, but mostly it is a problem of perception and adaptation—i.e. the barriers are mainly in your head. Around the world, people sleep in all sorts of odd arrangements, and a car is among the most convenient and comfortable. Security? It's not a major issue as long as you are discreet and choose your location carefully. I will cover site selection in a separate entry, but in general, you can sleep in your car almost anyplace you would feel comfortable parking it overnight. If your car doesn't attract attention, you won't either.

But how, physically, do you sleep in a car? Basically, you just obtain a sleeping bag or other covering appropriate to the weather, find something to use as a pillow and lie down in the back seat. If you're tired, you will sleep, and once you get used to it, you can probably sleep there as comfortably as in a bed.

Sleeping in a car is an acquired skill, however, and it takes some experience to do it elegantly. Below are some considerations for the first-time car sleeper. (Again, these rules tell you how to sleep in a car. In a separate entry, I will discuss where to sleep.)

1) You MUST crack one of the windows so you can breathe. [Wrong! As long as there is just one person in the car, nothing else using oxygen and the temperature is cool, you can leave the windows completely closed all night. I wouldn't think it possible, but it works! Apparently there's enough air to keep you alive. On cold nights, keeping the windows closed definitely keeps the car warmer, but it can make it much too hot on warm nights.] It doesn't have to be much, though: For one person, a quarter-inch opening in one window is sufficient. (It doesn't seem like enough, but I have learned from experience that it is.) If you fail to open a window, you might sleep okay for a couple of hours, but you'll eventually wake up gasping for breath. (It's not like you'll die in your sleep; your body will give you plenty of warning!) A quarter-inch to an inch is a good balance between air circulation, heat retention and security (so someone can't reach in the window). In mosquito-prone areas, you might even make the opening so thin that the mosquitoes can't get in. Same thing when it's especially cold outside: Experiment with how thin you can make the opening. You need some sort of opening in the car, but it is remarkable how little it can be. (Don't worry: Your body will tell you when you need more air!)

2) In warm weather in humid areas, mosquitoes may be an issue. Even one or two in the car can ruin your sleep. You deal with this by draping some sort of light cloth over the window opening. Camping stores or Evil Mega-Mart™ may sell mosquito netting designed specifically for this purpose, but any light, thin cloth or piece of clothing will do. (You may have to open your window a little more for adequate circulation.) Mosquitoes only become active in temperatures above 50°F, and they don't usually become a significant irritant until about 60°F, so you don't have to worry about them in cold weather. Mosquitoes need stagnant water to breed in, so you won't find many of them in the desert. They are also slow fliers and are easily blown away by the wind. I find the mosquitoes are really only an issue in humid, still areas in the summer. You can't really tell whether an area is going to be mosquito-prone until you go there, but you should always be prepared. If you find yourself in a situation where you can't protect yourself with netting, mosquito repellent may get you by, but that's yucky stuff I prefer to avoid. [Hot weather and/or mosquitoes are the one situation where car camping just doesn't work, especially in the Southeastern USA. Cold is no problem because you can always add bedding, but heat and humidity can force you into a motel.]

3) You can sleep in a car even when it is very cold outside, provided you have enough bedding. I have done it in temperatures as low as 0°F/-18°C. (by sleeping in three sleeping bags: one inside the other and a third one on top of me). The car protects you from rain and wind, which are very significant elements in keeping warm. The enclosed space is also warmed by your body heat, so the temperature inside is significantly warmer that the air outside. (That's one reason to keep the window opening small.) One consideration when sleeping in sub-freezing temperatures: In the morning you may have to scrape frost off the INSIDE of the windshield. One nice thing about sleeping in a car is that you can reach over, turn on the car's engine and warm the place up before you get out of bed!

4) Whenever possible, you should consult on-line sources to find out what the weather is expected to do overnight. The key statistic is the overnight low temperature. With experience, you'll learn what kind of bedding you need for various temperatures.

5) The best kind of bedding is a sleeping bag, since you can zip it up around you and eliminate drafts. Basic models at Walmart start at $15 (but I usually get the $20 model). You'll probably get more insulation value by buying two cheap sleeping bags, one inside the other, than one expensive one. The temperature ratings labeled on the sleeping bag are pretty much a fantasy; you'll have to experiment to see what works at various temperatures. In the 80s and above (°F), you may need no sleeping bag at all, maybe just a thin blanket. Between 50s and the 70s, a standard sleeping bag might do. Much below that, you'll probably need multiple sleeping bags. In my experience, there is no degree of cold that can't be addressed passively by adding more layers, but I've never tried to camp in Alaska. [Now I have slept in Alaska in the winter at -10°F, and it worked. See my winter pix from the Alaska Highway. I had two Walmart sleeping bags, one inside the other, covered with a third draped over me. I also wore two layers of thermal underwear and all my clothing. Slept like a baby. Conclusion: Cold is never a problem with enough bedding.]

6) A simple and extremely useful device is a single standard safety pin. A sleeping bag zips up around you, but it can easily become unzipped at night. The safety pin can be used to fix the zipper at the top.

7) Vans, mini-vans and large SUVs may give you more opportunity to stretch out, but they are colder than regular cars because your body has more space to heat. When renting a car, I usually go for a full-size or mid-size sedan as a good balance between space, warmth and cost.

8) In rainy or snowy weather, water is going to come in the window opening. You can prevent this by draping a sheet of plastic over the opening. (In rainy and mosquitoey conditions, you might need both the plastic and the thin cloth.) Alternatively, you might be able to make the gap in the window so small that the rain can't get in. [Not necessary, just close all the windows! The only problem is when the weather is both rainy and hot. Then you're screwed.]

9) Snow is usually no problem! A layer of snow can actually warm the car by providing more insulation. Snow usually happens when the outside temperature is hovering around freezing, so snowy nights are usually warmer than clear nights at the same time of year.

10) If you are forced to sleep in a car in cold weather without sufficient bedding, you can consider leaving the car running and the heater on. I am concerned with unnecessary wear on the engine, so I would be more likely to do it with a rental car than my own. I am not too concerned, however, about carbon monoxide poisoning. Modern cars are well-sealed, and if the heater is blowing air into the car and one window is cracked open, I feel safe. As an added protection, I might gauge the wind direction and park the car pointing into the wind. (People do occasionally die from carbon monoxide poisoning in running cars parked in enclosed spaces like garages—but it is usually intentional. You have to work at it.) Don't use anything like a gas heater in the car. That's just asking for trouble. It is safer (and probably more effective) to simply keep the windows rolled up. A lack of oxygen and excess of carbon dioxide will wake you up, whereas carbon monoxide kills you quietly.)

11) Very hot weather is the only time car sleeping might not work. You may have to fully open all of the cars windows to be cool enough, which makes you vulnerable to mosquito attack in humid areas. This is when you may be forced to move to a tent or even a motel room. In the desert where there aren't any mosquitoes, you don't even need a tent: You just sleep on an air mattress in the open. (Even when the daytime temp approaches 120°F, desert nights are always pleasant. Heat retention, however, can make the car unusable.)

NOTE: We in the industrial world are so accustomed to air conditioning that we may think we need it to sleep. In fact, nighttime temperatures are usually much cooler than daytime ones, and we need air conditioning only to remove the heat that builds up in buildings during the day. If you are directly exposed to the outside air, you rarely need the A/C. [Summer in the Southeastern USA and similar parts of the world can be a total bitch where your only option is an air-conditioned motel room. I'm tough, but not that tough.]

12) Unless you are very short, you won't be able to stretch out full-length in the back seat. You'll have to bend your knees. Sleeping like this is an acquired skill, and it may take several nights to get used to. I can sleep comfortably in the back seat of ANY car, even tiny ones in Europe. In small cars, you are almost sleeping in the fetal position. You don't have to lie flat to sleep; the important thing is that your whole body is at about the same level.

13) Several times during the night, you'll have to turn over. Your body wants to do this to prevent bed sores on one side, and if you can't turn, you'll wake up. During the day, you can practice how you are going to turn in this tight space. As long as you have two different positions to sleep in (Side A and Side B), you'll do okay. Handles above the doorframe are a nice little comfort feature because you can reach up to them at night to help reposition yourself.

14) While the back seat is usually best, you can sometimes sleep in the front seat. It depends on whether there is a console between the seats and what materials you have to mitigate it. Sometimes, in a car with bucket seats, you can build up both seats with suitcases or some form of padding so you can sleep comfortably across the console.

15) If you have no choice, you can try sleeping in the sitting position (say, if you are in a car full of people or cargo). This is never very comfortable, but it's no worse than sleeping in an airplane. You usually have more reclining space available to you than an airline flier does, so it's more like a First Class seat than Coach. Sleeping for a few hours upright might get you by, but you can never get truly healthy and restful sleep unless your whole body is at the same horizontal level. [I am finding it a lot easier to sleep in the sitting position with the practice of many overseas flights. Today, I can sleep in the driver's seat just fine.]

16) Obviously, you ought to pee before you attempt to sleep. Otherwise, you'll be waking up at night with the urge and possibly nowhere to relieve it. If you need to pee throughout the night, it is usually the result of a caffeine addiction. (See Things You Don't Need: Caffeine.) If you drink less, you'll pee less. If young children can last the night, you should be able to also. [At least you can stop drinking caffeine a few hours before you go to bed.] Before you go to sleep, you want to plan where you are going to relieve yourself in the morning. If you awake before dawn, there may be more options available to you than waking during the day. A pee bottle (or proverbial "pot to pee in") could be helpful, so be sure you have something to use for this. As for—ahem!—solid waste, you should know when in the day it usually happens and plan for it. (An actual restroom is best. Walmart, gas stations or fast food joints are good.) Again, excessive production of solid waste is usually a result of excessive intake.

17) Brush your teeth before you go to bed! Free sleeping is no excuse to ignore dental hygiene. Contrary to popular belief, you don't need water to brush your teeth, just a toothbrush and toothpaste. (I use a battery operated SonicCare™ from Walmart.)

18) You should probably sleep in your regular street clothes (or loose-fitting clothing that looks like street clothes). For one thing, this adds an extra layer of warmth, but you also want to be fully clothed in case you are woken at night by a police officer or security guard. (I'll discuss these potential interruptions in the entry on siting. It's usually benign. The worst they can do is ask you to move elsewhere.) Where possible, your clothing should be loose-fitting and comfortable. Ladies will probably want to de-bra, and gentlemen will want to loosen up "down below" (due to nighttime expansion). To the Free Sleeper, special night clothes or pajamas are an unnecessary vanity.

19) Some kind of sleeping hat is important to curb heat loss through your head. Your body places a high priority on keeping your head warm, so even if you are inside a warm sleeping bag, you could still be cold if your head is fully exposed. A knit winter cap does the trick, but if you don't have one, you can use a spare t-shirt: Just turn it upside down, stick your head halfway through the neck opening, and—Voila!—you have a sleeping cap. It makes you look a bit like an Arabian sheik, but it may be warmer and more likely to stay on your head than a knit cap.

20) Whenever I am sleeping in a position that I regard as unusual or uncomfortable to me, I usually take an aspirin tablet or two before going to sleep. This is specifically for my back (see my blog entry on it), but it also might address other muscular aches and pains before they happen.

21) If you need to get moving at a certain time, be sure you have some kind of alarm clock to wake you. A cellphone alarm will do, but it is very important to know your alarm clock. (Many times, I thought I set my alarm only to discover too late that I had done something wrong.) Greater than the risk of sleeping too little is the chance of oversleeping. Some parking locations that are very secure and discreet at night can be too exposed during the day, so you should consider whether you want to wake up and move on before dawn.

22) Unless you are in a very remote location with little chance of human interaction, when you wake up you probably want to get in the driver's seat and drive away as soon as possible. This gives you the warmth of the car's heater, but it may also address a security issue: When you are awake, sitting up and moving, it is easier for others to detect you. As with urban camping, I don't like to mix venues: The place where I camp is used only for sleeping, not for anything else, like eating or working on the computer. As soon as the sleeping function is complete, I move elsewhere.


Have I forgotten anything? We have yet to get into the social aspects of car sleeping—namely where to do it without attracting attention, but the above should cover the physical issues.

See separate article: WHERE to Sleep in a Car