What makes us tired in a car if other passengers are sleeping?

Tips for Sleeping Comfortably as a Passenger in a Moving Car – UnbuckleMe®

Why being sleepy is more dangerous than being drunk behind the wheel - Orange County Attorneys

Falling Asleep While Driving? A Sleep Expert's Advice

Sleep Talking & Parasomnias: 12 Things to Know

Dash cam video shows semitruck driver apparently falling asleep before crash

Why Traveling by Car or Plane Can Make You Sleep

Is Falling Asleep While Driving Gross Negligence?

Why does being a passenger in a car make you so sleepy? - Quora

How to Avoid Falling Asleep While Driving