Many parents know that babies often like to sleep in the car. The hum of the engine reminds your child that they are in the womb and may help them fall asleep. The shaking motion seems to stimulate the baby enough to breathe. The truth is, according to the American Academy of Pediatrics (AAP), sleeping in a car seat for long periods of time is actually unsafe. The danger stems from your child napping in an upright, seated, or reclined position.
When your baby sits down, their heavy head may tilt forward, causing it to be difficult to breathe…Even suffocation, which is why it is not safe for car seats (other than moving cars) to take a nap or stay overnight in the first year of life. The same risk exists for babies who sleep for long periods of time in upright strollers and baby swings.
That said, don’t panic if your baby dozes off in the car! AAP recommends that you move your child to a flat, firm sleeping surface as soon as you leave the vehicle.