A damaged exhaust system can also create problems in situations where a driver assumes the outdoor environment is sufficient protection.
A safer approach: Avoid using a running vehicle as a sleeping space. If you are too tired to continue driving, stop in a safe, designated location and arrange to rest somewhere appropriate, such as a hotel, staffed rest facility, or other accommodation.
If you need to remain in your vehicle temporarily, turn the engine off when conditions allow and prioritize a safe, ventilated location. Never sleep in a running vehicle inside a garage or other enclosed space.
If extreme temperatures make turning off the engine unsafe, seek a suitable indoor location instead of relying on the vehicle for prolonged rest.
2. Parking in an Enclosed or Poorly Ventilated Area
The second dangerous habit is assuming that a garage or covered parking space is safe simply because it protects the vehicle from sunlight and rain.
Garages and enclosed parking structures can allow exhaust gases to accumulate. Even relatively short periods of engine operation may create hazardous conditions depending on the space, ventilation, vehicle, and exhaust output.
The danger is not limited to the driver. Other people inside the building, including family members and neighbors, may also be exposed.
Carbon monoxide can move through connected spaces, meaning that an engine running in one area may create a risk beyond the immediate vehicle.
This is why vehicles should never be left running inside enclosed garages, even when the garage door is partially open.
A covered outdoor parking area may offer better airflow than a closed garage, but the label "covered" does not establish that a location is safe. Enclosed walls, restricted airflow, and the position of the exhaust outlet can all influence exposure.
A safer approach: Never run a vehicle's engine in an enclosed garage or similarly confined area. Move the vehicle completely into an open outdoor location before starting the engine, and avoid sleeping in it while it runs.
Homes and workplaces with attached garages should also have functioning carbon monoxide alarms installed according to the manufacturer's instructions and applicable safety guidance.
A carbon monoxide alarm provides an additional layer of protection, but it is not permission to sleep in a running car or to ignore an unsafe parking environment.
3. Ignoring Exhaust Leaks and Vehicle Maintenance
A vehicle may look perfectly normal on the outside while developing an exhaust-system problem underneath.
Exhaust pipes, joints, seals, and other components can deteriorate because of corrosion, physical damage, road debris, or ordinary wear. A damaged exhaust system may allow gases to escape from locations where they should remain contained.
If fumes enter the passenger compartment, occupants may be exposed without realizing it.
Some drivers ignore warning signs because the vehicle still starts, accelerates, and operates normally. However, a car's ability to run does not prove that its exhaust system is safe.
Potential warning signs include an unusual exhaust smell, a louder-than-normal exhaust, visible damage beneath the vehicle, or symptoms such as headaches and dizziness that appear when the engine is running and improve after leaving the car.
An exhaust smell should not be treated as a reliable indicator of carbon monoxide. Carbon monoxide itself is odorless, and dangerous exposure may occur without any recognizable smell.
A safer approach: Have suspected exhaust leaks inspected by a qualified mechanic. Follow the manufacturer's maintenance recommendations and address unusual engine or exhaust behavior promptly.
If occupants repeatedly develop headaches, nausea, dizziness, or confusion inside a particular vehicle, leave the vehicle and seek professional assessment rather than assuming the symptoms are caused by fatigue.
Never use the absence of an unpleasant odor as evidence that the cabin air is safe.
4. Sleeping for Long Periods Without Recognizing Heat-Related Risks
Another dangerous habit is treating a parked vehicle as a convenient place to sleep during hot weather.
Although air conditioning can reduce cabin temperature while it operates, the protection depends on the system functioning correctly and, in many vehicles, on the engine or another power source continuing to run.
If the engine stops, the air conditioner fails, or the vehicle loses power, the cabin may become uncomfortable or dangerously hot.
Vehicle interiors can heat rapidly when exposed to sunlight. The exact rate depends on outdoor temperature, sunlight, window area, vehicle design, and ventilation. Opening a window slightly does not reliably prevent dangerous heat buildup.
Heat-related illness can develop when the body can no longer regulate its temperature effectively.
Early symptoms may include excessive sweating, weakness, dizziness, headache, nausea, and muscle cramps. Severe heat illness can cause confusion, seizures, loss of consciousness, and organ damage.
Older adults, young children, pregnant individuals, and people with certain medical conditions may be particularly vulnerable. Some medications can also affect the body's ability to regulate temperature or respond to dehydration.
The absence of intense discomfort at the beginning of a nap does not guarantee that conditions will remain safe.
A safer approach: Choose a shaded, designated rest location and avoid relying on a parked car to maintain a safe temperature during extended sleep. When possible, rest indoors in a properly cooled environment.
Drink water regularly, particularly after exercise or prolonged exposure to heat. If symptoms suggest heatstroke, including confusion, collapse, or an extremely elevated body temperature, seek emergency medical assistance immediately.
Do not leave children, dependent adults, or pets unattended in a parked vehicle.
5. Treating Extreme Fatigue as Something a Short Nap Can Always Fix
The fifth dangerous habit is ignoring the underlying reason for feeling exhausted.
A short nap can improve alertness temporarily, but it cannot reliably compensate for severe sleep deprivation, untreated sleep disorders, medication effects, or certain medical conditions.
Driving while sleepy is a major safety concern because fatigue can impair attention, reaction time, judgment, and the ability to maintain a vehicle's position within a lane.
In some circumstances, a person experiencing severe sleep deprivation may have microsleeps, which are brief periods of involuntary sleep. These episodes can occur without the individual fully realizing what happened.
A driver who experiences heavy eyelids, repeated yawning, difficulty remembering the last few miles, drifting across lane markings, or missing road signs should not attempt to push through the symptoms.
Caffeine, loud music, opening a window, or turning up the air conditioning cannot guarantee that a dangerously sleepy driver will remain alert.
A safer approach: If you become sleepy while driving, pull over at a safe location as soon as possible. Arrange an alternative driver, use suitable accommodation, or take a brief nap in a safe place where doing so does not expose you to vehicle exhaust or extreme temperatures.