The ability of babies and toddlers to fall asleep in the car is one of the hidden weapons of parenthood. I know plenty of parents who have taken an impromptu trip around the block – ten or eleven times – in an attempt to get a little one to fall asleep for a nap or even for the night.

It makes sense; after all, the rocking motion of the car is close to that of a parent’s arms, and how many of us, as adults, haven’t fallen prey to the soporific effects of a long drive late at night?

Unfortunately, while car seat safety has come a long way and car seats provide a range of head rest types in order to make napping in the car more comfortable, research finds that the position of an infant’s body in a car seat isn’t ideal for long-term sleeping. A study put out by Pediatrics indicates that car seats can reduce oxygen levels in infants, thanks to the upright positioning of the body, which compresses the chest wall and makes the airway passage more constricted. Extended time in this position can contribute to a reduced level of oxygen reaching an infant’s vital organs.

Of course, this doesn’t mean that car seats aren’t safe. Babies and toddlers with full control of their necks don’t fall in the same risk categories, and car seats remain the federal standard in child transportation, saving lives every single day. What the study might indicate, however, is that extended car seat use can contribute to a higher risk for your infant.

It’s difficult to know just what to take away from this type of study. On the one hand, anecdotal evidence suggests that putting baby to sleep in the car seat is a great way for parents – especially of newborn infants – to retain their much-needed sanity. On the other hand, any situation that increases the potential for health risks is one we all want to avoid.

If you do use a car seat to lull your child to sleep, it’s probably best to move him or her as soon as you’ve reached home again. Although there’s always the risk that the nap will be brought to a sudden and loud end, it’s worth it just to know that your baby is resting in the most comfortable and most healthy position possible.