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- Nursery Articles -

Sleep Sack vs. Swaddle: Which Is Best for Baby?

Whether you’ve just brought home a new bundle of joy or you’re preparing for that delivery date, there are many blanket alternatives for keeping them safe and warm in their crib. If you can’t decide between a sleep sack vs. swaddle, we’ve got you covered with guides, tips and the answers to common questions!

What Is a Sleep Sack?

As the name suggests, a baby sleep sack is essentially a blanket your growing baby can wear, almost like a self-contained robe. Usually made of super soft materials like jersey or muslin, this is a safe, simple alternative to individual crib sheets. Your baby simply slips right in, and then you typically either button or zip the sleep sack up to keep baby tucked in all through the night.

Here are a few key features of a sleep sack:

  • Sleep sacks replace swaddles once (or before) baby starts showing signs of wanting to turn over on their own.
  • All your baby’s limbs should be free to “move about the cabin” inside a sleep sack.
  • Sleep sacks can be worn until your baby is old enough to safely transition to loose sheets.


When using a sleep sack, baby stays securely covered from chin to toe (and beyond). There’s plenty of room inside for them to move their little arms and legs, but unlike with a loose crib sheet, they can’t get tangled up or pull it off in their sleep.

What Is a Swaddle Blanket?

Swaddle blankets are used to wrap newborns up tight into what are affectionately known as “baby burritos.” New parents are usually taught swaddling techniques at their hospital or birthing center. The feeling of being bundled up is comforting for newborns because it reminds them of being in the womb—which might explain why curling up with a soft blanket and binging TV never gets old.

Here are a few considerations for swaddles:

  • They should be snug, but not excessively tight.
  • Every corner of the blanket should be tucked and secured so no piece can work itself loose.
  • Extra swaddle or blanket
  • Babies should sleep on their backs at all times, including when swaddled.
  • Swaddles are meant for newborns, typically up to 2-4 months old.
  • Swaddles should wrap around the arms and torso and stay loose around the legs.


The main benefit of baby swaddle blankets is that they stop babies from moving their arms. In addition to being soothing for newborns, they also ensure they don’t wake themselves up with their startle reflex—that sudden involuntary movement of an arm or leg.

Sleep Sack vs. Swaddle: What’s the Difference?

In essence, the main difference between a sleep sack and a swaddle is that a sleep sack is a loose-fitting blanket-like garment while a swaddle is a blanket wrapped snugly around a baby. Here are a few more key differences.

  • Mobility. Sleep sacks allow a baby’s limbs to move freely, while a swaddle keeps their movements restricted.
  • Arms. A baby’s arms are fully exposed in a sleep sack. A swaddle keeps them wrapped up.
  • Warmth. Swaddles hold in more warmth than sleep sacks.
  • Length of use. Babies may only sleep in swaddles for a couple months and could sleep in sleep sacks for up to two years—or longer.
  • Fastening method. Depending on the design, sleep sacks can be fastened by button, zipper or Velcro. Swaddles are wrapped and tucked.


Sleep sacks and swaddles aren’t meant to be used together. At a certain point in your baby’s development, swaddles will become dangerous for them to wear. Below, we’ll go over how to know when to make the transition.

How Long Should Babies Be Swaddled For?

According to the American Academy of Pediatrics (AAP), once a baby starts showing signs of trying to roll over on their own, it’s time to make the switch to a loose, non-swaddling infant sleep sack—if not sooner. This varies from baby to baby but tends to happen around two to four months. Once they start moving freely, there’ll be no stopping them!

The choice mostly comes down to your baby’s age and sleeping habits. When wrapped appropriately, your newborn will love sleeping in a swaddle while they adjust to sleeping on a flat surface. But a tight swaddle may not be the best choice as they get bigger and a little more mobile. Eventually you’ll need to switch to a transitional sleep sack or, later, a breathable baby blanket.

How to Choose the Right Piece for Your Baby

Now that you know when to dress your baby in each sleeping option, you’ll have a few more considerations for material, size, style and fastening type.

Material

While you want your baby to be warm and toasty in their swaddle or sleep sack, you also don’t want them to spend all night in a sauna. The material should be breathable, soft and lightweight, but still warm enough to keep them comfortable in your particular home.

Size

Both swaddles and sleep sacks come in sizes based on babies’ height and weight. It’s important to keep up with your growing baby to make sure they sleep safe and sound every night. Keep an eye out for them trying to break free while they’re asleep!

Style

Do you love a whimsical animal print, or do you prefer a classic pattern? Does your nursery have a fun theme or a perfectly curated color scheme? Can you already tell red is their color? Whatever your style preference, you can find a swaddle or wearable blanket to match!

Fastening Type

With enough practice, you’ll be able to swaddle like a pro. In the meantime, you may want to look for options that include helpful fastening options. Once your baby graduates to a sleep sack, you’ll have a wide range of fastening options to help you secure your little one with both hands tied behind your back—or at least with one hand tied up with a dirty diaper.

How Long Do Babies Use Sleep Sacks?

In short, parents can continue using sleep sacks for babies for as long as their sleeping beauties are comfortable in them. That could be as long as toddlerhood. Like so many other things at this age, it’s up to the baby, though the AAP doesn’t recommend less than a year.

Once they become mobile enough to start trying to crawl and roll around their sleeping space, they may start getting fussy about being confined. When in doubt, always consult your pediatrician about safe sleeping practices.

Transitioning from a Swaddle to a Sleep Sack

Once you start noticing your baby putting up a fight against the swaddle, it may be time to start planning the transition to sleep sacks or wearable blankets. Babies’ arms can seemingly have a mind of their own, so you can start by leaving their more active (or dominant) arm out.

Once they get used to this, you can release the second arm from the baby swaddle wrap. After a few more nights, your baby-rito may be ready to leave their “tortilla” in the drawer and start sleeping in a wearable blanket.

Common Concerns About Sleep Sacks & Swaddles

Still have questions about using a sleep sack vs. a swaddle? Here are a few more considerations to ensure you’ve got peace of mind and your little one sleeps peacefully.

Are Sleep Sacks Safe?

Researchers from Royal United Hospitals Bath concluded that sleep sacks are at least as safe—or safer—than other forms of bedding. As long as the construction, fit, quality and condition are in good shape, when used appropriately, sleep sacks are a doctor-approved option.

Are Sleep Sacks Better Than Swaddles?

The short answer is: It depends on how old, big and mobile the baby is. Once your baby starts trying to turn over on their own, sleep sacks are considered safer than swaddles.

Can Newborns Sleep in Sleep Sacks?

In general, yes! A newborn sleep sack is a safe alternative (when used appropriately) to a swaddle or loose bedding. Swaddles may be recommended for newborns, but you should always default to your doctor or birthing professional’s recommendation.

Do You Use a Sleep Sack & Swaddle Together?

Sleep sacks and swaddles are two separate sleepers with two different uses. Once your baby has graduated to a sleep sack, it’s not advisable to add a swaddle.

Hopefully this helps you decide which side of the sleep sack vs. swaddle debate to land on. Whichever choice you make when you get ready to dress baby for sleep, remember to consult your doctor, nurse, doula or midwife with questions or concerns about your baby. They’ll help you rest assured that your baby will sleep tight all through the night—or at least some of it!

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