What's the Difference Between a Swaddle and a Sleep Sack?

You have almost everything you think you'll need for your new baby. There are diapers stacked to the ceiling of your nursery closet and bottles lined along the desk where you've already set up your pump. Neatly folded newborn-size onesies and tiny socks line your baby's dresser drawers.

A bassinet is assembled next to your bed with a fresh fitted sheet pulled taut over the mattress. As you imagine your baby asleep, you start to wonder what you'll use to keep them warm and snug at night. You know that blankets and top sheets are a no-no for baby's first year, but you're trying to remember whether newborns need a swaddle or a sleep sack, and what the difference is between the two.

With so many products on the market, it's easy (and understandable) to get confused or overwhelmed. In a nutshell, swaddles are blankets that you use to wrap up your baby like a snug little burrito. On the other hand, sleep sacks are wearable blankets that zip up the front, usually allowing your baby's arms to remain free.

Both sleep sacks and swaddles keep soft fabric away from your baby's face, where it could block their breathing or become tangled. They are both considered safe sleep options, but there are a few key differences between the two. Ahead, we outline the pros and cons of sleep sacks and swaddles so you can decide which is right for your baby.

What Is a Swaddle?

A swaddle is a small, lightweight blanket fastened around your baby when you lay them down to sleep. Babies who are swaddled often feel secure when they are wrapped snuggly. Swaddling also helps to prevent the Moro reflex (the startle reflex), which causes babies' arms to flail upwards, periodically waking them.

"Swaddling is typically done by placing the baby on their back, folding each side of the blanket over their chest, and tucking it under both arms to secure the fabric snugly around the body," says Leah Alexander, M.D. FAAP, a board-certified pediatrician in New Jersey and the medical consultant of Amy Baby Review. "This gives the baby a sense of comfort."

To swaddle your baby, begin by folding the blanket into a right triangle and laying it out flat. Place your baby atop the blanket, with their shoulders resting just below the triangle's long side and their feet pointed down toward the right-angle corner.

Pull one corner down over the shoulder and across the body, tucking it behind the opposite hip. Then, take the bottom corner and pull it up over the other shoulder. Last, pull the remaining corner straight across your baby's body and tuck it behind.

Pros and Cons of a Swaddle

There are many reasons to swaddle your baby, as well as a few reasons why swaddles might not be the right fit for you. Let's dig into the pros and cons of swaddling.

Pros of Swaddling

Babies who are swaddled often sleep better. "Using a swaddle mimics both the snug womb and the mother’s warm embrace, allowing the newborn to relax and slip into sleep," says Heather Wallace, a certified pediatric sleep consultant, postpartum doula, and owner of BraveHeart Sleep Consulting and Postpartum Doula Care.

Unlike blankets or loose sheets, swaddles won't accidentally cover your little ones mouth and nose, and newborns won't become dangerously entangled in fabric like they might with loose bedding.

Cons of Swaddling

Swaddling works great—until it doesn't. Some parents find that no matter how hard they try, they can't get the swaddle on right, or their baby just seems to hate it. While some babies feel safer with their arms wrapped up, others prefer to keep their hands free for sucking. "Around 8 weeks old, your baby finds his fist and uses the fist to self-soothe," says Wallace. "However, if your baby is still swaddled, he does not have access to his fist, and sleep may become more difficult."

There is also a bit of learning curve when it comes to swaddling a baby. It can take a while to get it right. "It can be difficult to get the swaddle nice and secure, meaning it may loosen and come undone throughout the night," says Dr. Alexander. "For this reason, some parents prefer using more secure alternatives that are easier and faster to put on."

What Is a Sleep Sack and Who Is It Good For?

A sleep sack is a wearable blanket that zips up the front, and some contain holes for your baby's arms. Sleep sacks are a good alternative for babies who dislike being swaddled or have begun to self soothe by sucking on their hands.

You may feel more confident putting a sleep sack on your baby because there's really no room for error. You just put it on and zip it up. Parents concerned about a swaddle coming loose and blocking their baby's breathing might also feel more comfortable with a sleep sack.

If your baby is older than 8 weeks, or they are showing signs that of trying to roll from back to front, you need stop swaddling them for safety reasons. Babies who roll over can become trapped and their breathing may be compromised. A sleep sack is a safe product that can make it easier for little ones to transition away from the swaddle.

Types of Sleep Sacks

There are many varieties of sleep sacks on the market. "There are sleep sacks with zippers for easy diaper changes, as well as zip-up onesies that offer full body coverage for extra warmth and protection," notes Dr. Alexander. "Some even feature integrated foot pockets so you can keep your baby's toes warm without compromising their leg movement."

In general, simple is probably best. "I find that expensive sleep sacks are unnecessary, unless you live in a colder environment where you need a thicker sack to keep your baby warm," notes Wallace.

Wallace recommends the Zipadee Zip as a first sleep sack. "This is a unique and safe option to help babies transition from the swaddle to a sleep sack," she says. "The design of the Zipadee Zip provides a bit of resistance when the baby startles, yet it is loose enough to roll safely in."

Other sleep sacks that get a thumbs up from Wallace include the Woolino and the Kyte Baby. "The Woolino is a sleep sack that is helpful in colder climates, as it can regulate your baby's temperature as they sleep, while The Kyte Baby is extremely soft and made of bamboo rayon.

A Word From Verywell

Swaddles and sleep sacks are both safe options to keep your baby warm and comfy while they sleep. Swaddles offer a secure sense of comfort and can help babies sleep for longer stretches, but they can also be more difficult to figure out.

Sleep sacks are easier to use and they are the only safe option for babies who have started to roll or who are older than 8 weeks. Transitioning away from the swaddle can be hard for some babies, but it is worth it for their safety. There is no limit for how long you can you can use a sleep sack other than the length of your child's legs. If you have any questions or concerns about your child's sleeping habits, be sure to reach out to their pediatrician or healthcare provider.