Choosing to swaddle your little one with their arms in or out depends on how old your baby is. If you’ve got a young baby, arms-in swaddling is a game-changer for quality sleep. The snug arms-in swaddle best replicates the womb experience, helping to activate Baby’s innate calming reflex that quells crying and brings on sleep. That said, some babies start to get ready for arms-out around 3 to 4 months. (Before then, little ones simply don’t have enough motor control over their arms, so they have a tendency to bonk themselves awake a lot.) If your baby wakes themselves up when their arms are free, they’re just not ready to transition yet…and that is okay! You want to make sure you go at your baby’s pace. The BIG caveat: If your baby is rolling, you must stop arms-in swaddling immediately. However, if your rolling baby is in Sleepea, you can be comfortable continuing to use it as long as your bub has BOTH arms out—and weighs 12 kilograms or less.