It depends where you are if it’s OK to sleep in a car overnight. According to the California State Department of Transportation, it is legal to sleep in your car at a rest stop for up to eight hours. However, this isn’t the case for all cities and states across the country.
Additionally, it is important to keep the engine off in order to prevent harmful exhaust fumes from entering the vehicle. If you’re sleeping in your car in winter conditions, it’s important to have a warm sleeping bag or other insulation to stay warm. Also, keep a charged phone on you in case of emergencies.