Swaddling is a great technique that helps newborns and small infants feel warm and secure in their crib — but once they begin to move with more independence, it’s usually time for mama to retire her signature move.
Enter the sleep sack!
Sleep sacks are specifically designed to keep babies safe and warm and replace loose blankets that may be sleeping hazards.
We’ve rounded up the best baby sleep sacks to help baby experience the benefits of swaddling without the complicated wrapping.
- Sleeveless to prevent baby overheating
- Designed for baby’s comfort
- Available in variety of colors
- Designed to allow healthy hip movement
- Comes in cute unisex prints
- Sizes allow for baby’s growth
- Micro-fleece fabric
- Features a “back is best” embroidery
- Available in 26 colors
- Unzips from the bottom
- With 4 sizes and 42 colors
- Generous size
- Sleeveless to prevent overheating
- Great for cold climates and winter
- Sleeves are wide for ventilation
- Dual zippers for diaper changes
- Made of 100% cotton
- Comes with double zippers
- Adjustable straps
What Is a Sleep Sack?
A sleep sack is a one-piece wearable blanket designed to keep your baby warm and safe in their crib. It’s a special garment that looks like any sleeper at the top, but fans out into a closed sack at the bottom — think of it as a tiny sleeping bag your baby can wear.
Sleep sacks are designed to replace loose blankets that may be sleeping hazards in bassinets and cribs.
They come in many different styles and fabrics for every season and occasion. Many also have different fasteners, such as snaps or zippers to make putting one on your tired, fussy baby as easy as possible.
They’re also a great sleeping solution for newborn babies, when swaddling seems too daunting or when you want to allow your little one some mobility with their arms and legs.
Benefits of Sleep Sacks
There are many reasons parents choose sleep sacks when laying their little ones down for the evening.
These one-of-a-kind sleeping solutions have a variety of major pros that parents love and babies can benefit from.
Letting babies sleep with loose blankets, pillows, and even stuffed animals have been linked to Sudden Infant Death Syndrome — often known as SIDS. SIDS is what happens when an otherwise healthy baby passes away before the age of one with no apparent cause (1).
SIDS most often occurs during sleep, which is why ensuring babies have the safest sleep environment possible is so crucial. Sleep sacks are designed to eliminate the danger of a loose blanket smothering your little one and keep their crib free of clutter that might cause SIDS.
Additionally, when babies begin to turn over onto their backs in a swaddle, it’s impossible for them to turn back over. This is a suffocation risk that sleep sacks can take care of.
Sleep sacks offer more mobility for baby’s arms and legs, negating some of that risk. They offer a little more freedom to move, and when babies have the strength to do so, they can more easily right themselves in a sleep sack.
Even when they can’t, there’s less risk of a blanket being in the way to impede their breathing.
Sleep Sack Fact
Before they’re born, babies become accustomed to the warm, secure environment of the womb — which is why they enjoy being swaddled once they’re out in the world.
Swaddling allows them to experience some of those same sensations, ultimately putting them more at ease. However, when babies begin to grow and gain the ability to move around more, swaddling tends to become too restrictive for them.
A sleep sack is a great alternative to a swaddle because it provides the warmth and softness of swaddling blankets with more allowance for movement. Sleep sacks are also a great tool to help transition babies away from swaddling.
We all know that raising children can teach us many lessons — one of those lessons just happens to be a new meaning for the word “exhaustion.” Swaddling a baby takes energy and time.
If you need a solution for getting your baby ready for bed quickly, a sleep sack is the perfect one. Many models are designed to be streamlined and easy to use. They’re a quick snap or zip inside and your little one is ready for bed!
That way you get to the dishes, or the laundry — or taking a moment of rest for yourself.
How to Choose the Best Sleep Sack
First, are you shopping for a baby or a toddler?
- Baby sleep sack: These are typically designed for use with babies from newborn up to about 36 months depending on size.
- Toddler sleep sack: Once your little one has grown up some and can stand on their own, it’s time to switch to one of these. Toddler sleep sacks have holes for feet, so they won’t trip and hurt themselves the way they might in a regular sleep sack when standing.
Both baby and toddler sleep sacks come in a wide variety of materials, for summer, winter, or all-seasons.
An added bonus to toddler sleep sacks — they can keep your little one from climbing out of their crib!
Editor's Note:Mary Sweeney, BSN, RN, CEN
Sleep Sack Features
Apart from the type of sleep sack, there are some features you can look for when shopping to ensure you’re getting the best product possible for your baby’s needs:
- Sturdy zippers, especially with protectors.
- Zippers that run from top-to-bottom.
- Removable sleeves.
- Shoulder straps featuring snaps.
- Natural breathable materials.
The Best Sleep Sack Reviews of 2021
Here are our favorite sleep sacks on the market.
1. Baby Deedee Fleece Sleep Sack
This cozy sleep sack is made from polar fleece, a warm but breathable material that can keep your little one snug as a bug throughout the winter season. This is the perfect sleep sack for anyone who lives in a colder climate or has an aggressive air conditioner.
Not only does this one have an inverted zipper for baby’s safety, but it also features unique shoulder straps that open and close with snaps, making putting it on and taking it off a breeze. This is a great choice for mamas who want to streamline their bedtime routine without sacrificing comfort.
- It is sleeveless to prevent baby overheating.
- Its unique cocoon shape is designed for baby’s comfort.
- It’s available in a variety of colors.
- Some mothers found the zipper did not stand up to their washing machines.
- Polar fleece is polyester, which means it is a synthetic fabric.
2. Burt’s Bees Wearable Blanket Sleep Sack
The Burt’s Bees Baby Beekeeper Wearable Blanket — try saying that five times fast — is made of 100 percent organic cotton, and nothing else. This means it’s gentle on your baby’s skin and made of high-quality material. From a laundry standpoint, that means it’s easy to wash!
It also has a built-in zipper guard to keep your baby’s skin safe — which also comes with a lifetime guarantee. We like the fact that they’ve been worn and tested with care, and the security that comes with buying from a unique established brand like Burt’s.
- Designed to allow healthy hip movement for baby.
- It comes in cute unisex prints.
- The sizes are roomy to allow for baby’s growth.
- Some moms felt the sizing was too large.
3. HALO Micro-fleece Wearable Blanket
This sleep sack runs from small all the way up to extra-large, which is designed for babies who weigh 26 to 36 pounds. The design is specially engineered to ensure baby has enough leg room for healthy hip development.
We love the soft embroidery details, the quality of the fabric, and the reassurance that can come from investing in an established brand like HALO.
- Its micro-fleece fabric is soft on baby’s skin.
- It features a “back is best” embroidery, reminding caretakers to lay baby on their back.
- It’s available in 26 colors.
- Some mothers found the zipper to be easily breakable.
4. HALO SleepSack 100% Cotton
This versatile sleep sack is made from 100% soft and breathable cotton that may help regulate baby’s body temperature.
The TOG rating of 0.5 coupled with the spacious sizing, makes it versatile for different temperatures It’s cool enough for summer, but roomy enough to be layered with warmer sleepwear in winter.
It’s perfect for parents who only want to purchase one sleep sack and use it the entire year round in any location.
- It is machine-washable for easy cleanup.
- It unzips from the bottom for easy diaper changes.
- It comes in 4 sizes and 42 different colors.
- Some mothers found the neck hole was too large.
- Some mothers feel that the zipper is low-quality.
5. HALO Early Walker Sleep Sack
Change can come on fast once your baby turns into a toddler, and this sleep sack is ready to keep up. It comes in a cute variety of patterns that makes it perfect for growing girls and boys alike. We love that it’s sized to allow children to tuck their feet inside or keep them out.
This sleepsack is sized to be worn over regular pajamas, and another great feature is that it unzips from the bottom, which allows for easy diaper changes.
- Generous size allows kids to tuck their feet while sleeping.
- Sleeveless to prevent overheating.
- Great for cold climates and winter.
- Some mothers found the sizing too large for their babies.
6. OuYun Baby Organic Sleep Sack
Our favorite part of this particular item? With this sleep sack, you get the best of both worlds — sleeved and unsleeved.
This is because the sleeves are actually removable, allowing you to adjust your baby’s sleeping conditions before they go to sleep or even during the night if you feel they’re becoming overheated.
Zip them on or off depending on your nursery conditions, and your little one is good for a night’s rest.
- Its sleeves are wide for warmth and ventilation.
- It features dual zippers for ventilation and diaper changes.
- It’s made of 100 percent cotton.
- Some mothers found the fit to be too large.
7. Nested Bean Zen Premier Sleep Sack
This unique sleep sack is made with lightweight rayon from bamboo, making it super breathable for those hot summer nights and daytime naps. We love that the design is practical and well-thought-out, while still being adorable.
It also comes with a unique feature — a lightweight sewn into the chest to mimic the gentle weight of your palm on their chest while they sleep. If your baby is a fussy sleeper, this sleep sack may be a must-try.
- It comes with double zippers to ease diaper changes.
- It has adjustable straps so your baby can grow with it.
- It is sleeveless to ensure your baby maintains a healthy temperature.
- It’s only available in sizes up to 15 months.
- It costs more than other sleep sacks.
- The chest weight is ineffective once baby can turn over to its stomach.
Sleep Sack Safety
As with all products out on the market, sleep sacks are not without their potential safety hazards. They have to be purchased carefully and used properly to minimize the risks.
There are two main concerns when it comes to using sleep sacks.
Similar to swaddling, it’s important to check on your baby when you’ve put them in a sleep sack — especially in the summertime. Keep an eye on their temperature, and if they seem too warm, change them into some cooler clothing.
Some signs your baby is overheated include (2):
- Warm to the touch.
- Red skin.
- A rapid heartbeat.
- A fever.
- Vomiting — in extreme cases.
To avoid overheating, it’s key to put your baby in a sleep sack that is appropriate for the time of year and their immediate environment. If you believe your baby is overheated, switch them to a lighter sleep sack or remove some layers.
Lay them down in a cool area, and try putting a cool washcloth against their skin. If your baby doesn’t show signs of improvement, or their condition worsens, it may be time to go to the ER.
Some sleep sacks are made of material such as wool, which is breathable and great for all seasons. Some sleep sacks are made of thicker materials like fleece, which should be used for winter use only.
2. Choking Hazards
Another danger when it comes to sleep sacks? Some of them have fancy embellishments or less-than-ideal zippers. If those zippers break, they can become a choking hazard. Those cute little details might detach and also become dangerous.
It’s key to ensure you get trusted, safety-tested brands when purchasing sleep sacks. It doesn’t hurt to check in on your baby semi-frequently while they’re in dreamland — just to ensure everything is okay.
The Bottom Line
Our pick as the best sleep sack is the Burt’s Bees Wearable Blanket, not only because it’s made of 100 percent soft organic cotton, but because of its thoughtful design. The grey-and-white rugby stripe design is particularly appealing and can work for little boys and girls alike!
Choosing the right sleep sack for your little one is all about personal preference, and considering what you need the sack for. Is it for travel? Winter? Do you want something for all seasons?
Asking these critical questions will help you decide on the best, most comfortable, and safest sleep sack for your baby.