I am often asked how to transition a baby from being swaddled to having their arms free and sleeping with a sleep sack, and why use a sleep sack and not just regular thick pajamas?

In my opinion the best time to transition your baby out of the swaddle is at 4months old. This is when your baby’s nervous system has matured enough and now he won’t be constantly waking himself with jerky hand movements from the moro reflex. You need to transition your baby gradually. I recommend swaddling your baby with one arm out first. Let him sleep like this at night time and during the day for 5 days. Bear in mind, that the first night or two your baby is going to be a little restless as he gets used to the feeling of having his arm free. Then 5 days later, swaddle your baby with both arms out.  Again your baby will probably take a couple of nights to transition. Having both arms out will be quite strange for him and often you will see he will wake himself with the movement of his arms. To help make this a little easier, I like to offer a transitional object. A great transitional object is a baby blankie or lovey. if you place the blankie, in one of your baby’s hands this will allow your baby to feel it as he goes to sleep. Being swaddled, your baby has gotten used to feeling of the swaddle blanket, so this gives your baby something to replace that blanket feeling. After five days of swaddling with both arms out you can switch to using a sleep sack. This should be an easier transition for your baby as he is already used to sleeping with both arms free.

I prefer to use a sleep sack instead of warm pajamas because it will resemble a blanket a little more than pajamas will. Not to mention if you have an active baby, it will take him a little longer to be able to move as freely in the sleep sack as he could do in pajamas. I’ve known a few little ones who, when they are bigger like to swing their legs up and over the side of the crib, this is less easy to do in a sleep sack! It is absolutely fine to use a sleep sack until your baby moves into a big bed. As long as he is in a bed by about two and a half years old.