The Babyzen YOYO is approved for use from 6 months to 48.5 pounds. So if your child is 6 months or older they can definitely sleep in the stroller with the seat reclined. However, if you are wanting the stroller for a baby younger than 6 months, you will need to purchase either the Bassinet or the Newborn Pack. While these bassinets are not approved for overnight sleeping, they create a cozy safe place for baby to rest and nap during a walk, at a restaurant or when visiting friends. You also have the option to purchase car seat adapters to connect a compatible car seat to the YOYO. Please note it is not recommended to have your baby in their car seat for long periods of time.