Fatigue is a major road-safety concern. Driving while sleepy can impair attention, reaction time, and decision-making, increasing the likelihood of a crash.
When you notice persistent yawning, heavy eyelids, difficulty concentrating, or drifting between lanes, stop driving as soon as you can do so safely.
Choose a designated rest area, a staffed facility, or another appropriate location where you can stop without obstructing traffic. If you need substantial rest, consider sleeping in suitable accommodation rather than relying on a parked vehicle.
If you are resting in a car, avoid enclosed garages and other confined spaces where exhaust gases may accumulate. Never run a fuel-burning engine in an enclosed area, even if a door or window is open.
Keep children and vulnerable passengers supervised, and do not leave anyone in a parked vehicle when temperatures could become unsafe.
If your vehicle has an exhaust-system fault, do not use the engine to provide heating or cooling until the problem has been assessed. Consider arranging professional assistance rather than risking exposure.
It is also worth remembering that carbon monoxide exposure can occur without warning signs that are easy to recognize. A carbon monoxide detector designed for vehicle use may provide an additional layer of protection in appropriate circumstances, but it does not replace vehicle maintenance or safe operating practices.
If you suspect carbon monoxide poisoning, leave the vehicle and move into fresh air immediately. Call emergency services, and do not re-enter until the area has been declared safe. Anyone experiencing symptoms should receive urgent medical evaluation.
Final Thoughts
Sleeping in a parked car is not automatically fatal, and running air conditioning does not itself cause carbon monoxide poisoning. The danger depends on the vehicle, exhaust conditions, parking environment, temperature, and other circumstances.
The most important precautions are to avoid running a fuel-burning engine in enclosed spaces, maintain the exhaust system, never leave children unattended in a vehicle, and respond immediately to symptoms that could indicate poisoning or heat-related illness.
A cool cabin may feel comfortable, but comfort alone cannot establish that an environment is safe. When fatigue makes driving dangerous, stop somewhere appropriate and prioritize a safe, adequate rest.