From 15 kilos on, when they are beginning to use a seat from groups II and III, they can sometimes slip from under the shoulder strap while trying to get comfortable when asleep. Although it is a pity to wake them, you must never allow them to travel like this. It is not safe.
The child restraining systems in groups II and III lift the child up so that they reach the required height to use a seatbelt. These devices don’t have a harness or straps; it is simply the seatbelt that holds them in the seat. This is why it is so important for the seatbelts to be correctly adjusted, with the lower strap flat across the pelvis and the shoulder strap placed between the breastbone and the collarbone, without rubbing on the neck.
Both of the straps act together to hold both the upper and lower parts of the body correctly in place in the event of an accident or sudden braking. If the shoulder strap is under the arm, the direct pressure on the abdomen can cause serious internal injuries. If it is behind the back and the seatbelt is too loose, in an accident it could cause a dangerous submarining effect.
When children are asleep in the car, it is important to, every now and again check that the seatbelt is properly located. If you notice that the seatbelt is not correctly placed, you must change their posture until it is. There are no excuses. As our concentration ought to be on the driving, it is a good idea to pull in somewhere safe and readjust the child restraining system to a safe position.
It doesn’t matter if you are almost there or how soon you are going to arrive, you never know when we could find ourselves in a dangerous situation.
From the MAPFRE FOUNDATION we never tire of repeating that it is unacceptable for any child to travel in a vehicle without the corresponding child seat, we can’t allow this to happen, it is too dangerous. http://www.seguridadvialinfantil.org/es/prevencion/habitos-que-se-deben-corregir/habitos-de-educacion-vial/
A child’s sleep is important but not as important as their safety and their future - always act responsibly.