swaddle blanket or swaddle blanket

What is the Difference Between a Swaddle and a Sleep Sack?

Apr 1, 2020

swaddle blanket or swaddle blanket

What is the Difference Between a Swaddle and a Sleep Sack?

Apr 1, 2020

All parents and caregivers need to understand the difference between a swaddle and a sleep sack.

This post will explain the important differences between a swaddle and a sleep sack as well as when you should stop swaddling and why (hint: SIDS).

If you’d like to jump ahead and read the FAQs about swaddling and sleep sacks, click on your question below!

All evidence-based sources are linked to throughout the post for further reading.

I want to give a major shout out to Safe Sleep and Baby Care — Evidence Based Support for enlightening me about all of this! Check them out.

There may be affiliate links in this post. Read this disclosure policy to learn more.

Overview: What is the difference between a swaddle and a sleep sack?


Restricts arm movement

Tight around the chest

No longer safe when baby shows signs of rolling (usually by 8 weeks)


Does NOT restrict arm movement at all

Loose around the chest

Safe for all ages (including newborns and toddlers)

Now let’s tackle some frequently asked questions about swaddles vs. sleep sacks…

What is a swaddle?

A swaddle is a ‘blanket’ used to wrap newborns in a manner that snugly contains their arms and/or compresses their chests.

There are 2 general categories of swaddles:

1 – Swaddle Blankets

This is the traditional way of swaddling that’s kind of like turning your newborn into a burrito.

The hospital uses receiving blankets to swaddle newborn babies. At home, many parents use muslin blankets because the material is lightweight.

There are several ways to swaddle. This video below teaches one of the more popular methods.

Here are two cute examples of swaddle blankets:

(Note: Muslin swaddle blankets are great to have because they have lots of other uses when it’s no longer safe to swaddle).

2 – Swaddle Sacks / Pods

This alternative way to swaddle is often preferred by new parents because it’s easier and has less room for error.

swaddle sack newborn baby

Swaddle sacks and swaddle pods come in all different forms. Here are a few:

You might want to get a couple of different styles and see which your baby likes best.

What are the benefits of swaddling?

The only actual benefit of swaddling is that babies tend to sleep better when swaddled (and as a result, parents get more sleep).

Babies enjoy being tightly wrapped because it feels like being in mom’s womb.

Swaddling prevents flailing arms (Moro Reflex) that often wake baby from sleep.

Swaddling does not decrease the risk of SIDS.

Do I have to swaddle my newborn?

No, you do not have to swaddle your baby.

Swaddling isn’t for safety, it just provides comfort.

How do I know if my baby is swaddled correctly / if the swaddle sack fits correctly?

If you are using a blanket to swaddle, make sure that it’s snug on the upper body and can’t easily come undone.

Take care to ensure that the fabric can’t ride up over baby’s mouth.

Unlike the top, the lower portion of the swaddle should be loose to encourage healthy hip development.

The same advice goes for checking the fit of a swaddle sack. Start with the manufacturer’s size guidelines for height and weight. Make sure the fabric can’t ride up over baby’s mouth. Ensure that baby’s hip region isn’t compressed.

When do we need to STOP swaddling?

The following is an excerpt from the current 2020 AAP guidelines:

“Parents should stop swaddling as soon as their baby shows any signs of trying to roll over. Many babies start working on rolling at around 2 months of age.”

Many safe sleep experts err on the side of caution, directing parents to stop swaddling at 8 weeks or first signs of rolling, whichever comes first.

My baby just rolled — what should I do?

You must stop swaddling cold turkey if your baby is rolling or showing signs of rolling.

No transition.


Because if a swaddled infant rolls onto his stomach, the risk of death is high.

You should expect a few rough nights while baby gets used to having his arms free. Everyone will sleep poorly during this time. As lousy as that is, the alternative is putting your baby’s life in danger.

As long as you’re wide awake, one thing you can try is using your hands to apply light pressure on baby’s arms for a few minutes after you put him in his crib/bassinet. This will help with the Moro Reflex as he’s falling asleep. Ultimately, time and consistency are the only things that will work.

Read all about what to do when your baby starts rolling.

What should we use when we can no longer swaddle our baby?

Once your baby is exhibiting signs of rolling and you need to stop swaddling, you can switch to a sleep sack.

Related post: How to Keep a Baby Warm at Night (Evidence-Based Guide)

What is a sleep sack and why use one?

A sleep sack is a wearable blanket.


The purpose of a sleep sack is to keep your baby warm without the risk of loose bedding.

Actual blankets are unsafe for babies until they are at least 12 months old as loose bedding significantly increases the risk of SIDS.

Sometimes you’ll see sleep sacks advertised as the following and they are all the same thing:

  • Sleep bag / sleepbag / sleeping bag
  • Sleepsack / sleeping sack / sleep sac / sleepsac
  • Wearable blanket

How do I know if my baby's sleep sack fits properly?

Typically, manufacturers provide size guidelines based on age, length, and weight. This is where you should start.

Different from a swaddle, a sleep sack should not limit baby’s range of motion or compress the chest.

You should also check that the neck hole is small enough so that the fabric can’t ride up over baby’s mouth.

Can newborns sleep in sleep sacks?

Absolutely! Sleep sacks are safe for all ages, as long as they fit correctly.

In fact, if you can get your baby to sleep without being swaddled by using a sleep sack instead, you will save yourself a potentially tough transition.

Is the Zipadee-Zip safe?

The Zipadee-Zip is a popular swaddle transition product falls into a gray area of safety.

It contains baby’s arms (which would make it a “swaddle”), but it’s very loose. It allows baby’s arms to move freely and there’s zero compression around the chest.

If you decide you want to use a Zipadee-Zip, make sure to follow all manufacturer guidelines, which include the following:

* Baby can roll over
* Baby is at least 3 months old
* Baby weighs at least 12 lbs

This is Aden wearing a Zipadee-Zip sleeping safely on his back in an empty Pack N Play. (Pacifiers are fine).

Is the Nested Bean 'Zen Swaddle' safe?

In short, probably not.

Read my in-depth article here: Are Nested Bean Sleep Sacks Safe?

Is Baby Merlin's Magic Sleepsuit safe?

Baby Merlin’s Magic Sleepsuit, a “swaddle transition” product, falls into a gray area of safety.

Given what we know about safe sleep and developmental milestones (all addressed above), the Magic Merlin doesn’t make sense to buy if you are planning on using it safely.

Here’s why:

The company tells you not to use it when baby is able to roll:

“The Magic Sleepsuit is designed for back sleeping in the crib. It is not to be used for tummy sleeping.

So, if it’s unsafe for babies to sleep on their bellies in this product, then it would ONLY be safe for babies who are showing zero signs of rolling.

This product *might* make sense for a parent wanting to get a jump start on transitioning their not-showing-signs-of-rolling-newborn out of a swaddle…

…except the company says the following:

“The Magic Sleepsuit is designed to be used after the swaddle, not with a newborn as a swaddle alternative.

(Insert shoulder shrug emoji, right?)

The next concern to note is that due to its weight and thickness, the Magic Sleepsuit poses a risk for overheating. (Overheating is a risk factor for SIDS).

Now I’d like to point out a few red flags.

Red flag #1: This absurd statement from Baby Merlin’s website:

“We suggest that you begin using the Magic Sleepsuit with naps and check on your baby frequently the first few days to monitor your baby while in the suit.”

Say what? This sentence alone is enough for me to never want to use this product with my own baby.

Red flag #2: They sell this product for babies 6-9 months and 18-21 pounds.

Most babies are already actively rolling by the time they are 18 pounds.

Rolling is considered a 6-month milestone by the CDC. And as we’ve already discussed in this post, rolling can happen much earlier. The AAP wants parents to plan for rolling at 2 months. This is quite a bit earlier than 6-9 months!

Anecdotally, Aden rolled at 4 months and was among the later ones to do so in my due date group.

Do you think all parents are aware that a product like this reduces a baby’s ability to wake himself up if he’s not getting enough oxygen — which is incredibly dangerous if the infant rolls onto his stomach? Absolutely not.

This means that well-meaning parents are potentially buying this product for their older babies who are already rolling, not realizing that they’re putting their lives at risk.


As with many products, due to lack of regulation, the Baby Merlin’s Magic Sleepsuit is up to parental discretion.

If you choose to use this product, be sure to follow all manufacturer guidelines regarding proper fit and when to start/stop using it.

What are the best and safest sleep sacks?

There are no official “best sleep sacks” as far as safety goes. That said, a sleep sack without any gimmicks is your best bet.

Sleep sacks aren’t regulated, so it’s most important to go by fit and to approach shopping for sleep sacks with a basic understanding of everything we have discussed in this post.

Make sure that it doesn’t say “swaddle transition” (or anything with the word “swaddle”) if you’re looking for an actual sleep sack.

Tons of brands make sleep sacks. Here are two of my personal favorites:

How many sleep sacks should I buy in each size?

There is certainly no hard and fast rule about how many sleep sacks to buy in each size.

At a minimum, you’ll probably want to have 2 sleep sacks in each size in case one gets dirty.

If you’re anything like me and don’t end up doing laundry every day, you’ll be much happier having 4 or more per size.

I also like to have a mix of lighter weight sleep sacks and warmer ones.

Help me normalize safe sleep!

My goal: Make safe sleep instagrammable and pin-worthy.

By making science and safety pretty, I’m hoping to attract the attention of parents and caretakers who might have otherwise remained in the dark.

If you’d be willing to share this post on your own social media or pin any of my graphics on Pinterest, that would be so awesome.

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Correct me if I'm wrong!

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I have no ego in this. If you think I got something wrong and want to tell me, I'm happy to be corrected with evidence from a reputable source. Contact me here.