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2022-05-20 02:45:57 By : Ms. Sunny Chen

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Baby sleep may seem like the most natural thing in the world. But that doesn't mean it always comes easily — to the baby or the caregivers. 

You may find yourself wondering: Is my baby too cold at night or too warm? Will they get tangled up in any extra material at night? How can I keep them safe and comfortable?  It is important for an infant to have their arms free once they are close to rolling over or to their side (usually around 3 to 4 months), and a "sleep sack," also called a "wearable blanket," just might be your golden ticket to long nights of safe, cozy sleep for your little one. 

For this guide, I spoke to a pediatrician, a dermatologist, and a baby sleep consultant about what makes a great sleep sack and tested a variety of options with my 1-year-old daughter. I considered several fabric weights or "TOGs," short for "Thermal Overall Grade," to fit different climates and seasons, so baby can stay warm enough on cold nights and avoid heat rash on hot ones. Whether you're looking for a newborn sleep sack, one for an older baby or toddler, or options for winter and summer, read on for our top picks.

The Baby Deedee Sleep Nest Lite is made of gentle cotton fabric and has an easy on-off design that helped push the soft but durable sleep sack to the top of the heap.

Pros: 100% jersey cotton, roomy, easy to use snaps at the shoulders, zipper doesn't touch baby's skin

Cons: Lower pouch design means you have to pull baby's legs out of the sack to change a diaper

Sizes: 0 to 6 months, 6 to 18 months, 18 to 36 months

Our experts say jersey cotton is a good material for sensitive skin and unlikely to cause irritation. The Baby Deedee Sleep Nest Lite is a jersey cotton sleep sack that is so soft you'll feel confident placing it on your baby's bare skin, though the double layer sack is meant to be worn over your baby's sleepwear. 

Two large metal snaps at the shoulders make it easy to get a sleeping baby strapped in without having to wiggle their arms through holes or sleeves. Even better, the snaps don't touch the baby's skin. A large reverse center zipper means you can easily access the bottom for midnight diaper changes. A perimeter zipper design would be slightly easier, since you wouldn't have to scoop baby's bottom all the way out of the sack to change the diaper. But unless your baby is a Houdini and a half, they won't be able to work this zipper on their own.

When I get home late from work and my baby is already falling asleep, it's easy to gently wrap this sack around her, snap the shoulders, and zip it down the middle. The sack can be worn over a onesie or a similar pajama layer for ultimate climate comfort throughout the year. On cold nights, I paired the Sleep Nest Lite with a long cotton PJ set, and on hot nights, with just a short-sleeve onesie.

The sleep sack stood up to our washing and drying tests with no visible signs of wear and tear.

The extra gentle fabric and fastener materials used in this sleep sack from Burt's Bees prevent irritation in babies with extra sensitive skin.

Pros: 100% organic cotton, zipper guard, breathable

Cons: Lighter weight, center zipper design offers slightly awkward diaper access

Sizes: 0 to 6 months, 6 to 12 months, 12 to 18 months

The Burt's Bees Beekeeper Organic Wearable Blanket is made of organic cotton and comes in two weights. For sensitive skin, the lighter-weight .5 TOG sack is best since it's breathable and does not have the polyester fill and extra layers of the 1.5 TOG version.

My baby's skin is so sensitive that she gets red welts from almost any irritant, but she never had a reaction to this soft, breathable sack. It has a large, easy-to-use reverse metal zipper. While metal shouldn't touch a baby's sensitive skin, the sack has an interior zipper guard and snap tab zipper pull cover, which ensure baby's skin never comes into contact with the fasteners.

The sack's center zipper design is safer for skin that might react to metal, unlike a perimeter zipper. The inverted zipper makes for easy diaper access, though I felt like I was pulling my baby's whole bottom out of the sack for diaper changes.

I put it through a few wash and dry cycles and found only a little pilling. It should be dried on the gentle setting.

The Love to Dream Swaddle Up Transition Bag helps move your baby from a tightly wrapped burrito to a snuggly but safe roller by allowing them access to different arm positions.

Pros: Roomy healthy hip design, multiple arm positions, babies can self-soothe with their hands up

Cons: Neck hole is a bit narrow for some babies, material around hands stays wet if baby sucks hands through cloth

Sizes: Medium (13 to 19 pounds), large (19 to 24 pounds), extra-large (24 to 31 pounds)

Many newborns love being tightly swaddled at night because it mimics the feeling of being in the womb, so it's sometimes difficult to put them in a roomier sleep sack. The cotton muslin Love to Dream Swaddle Up Transition Bag helps with the switch because lots of babies discover their hands right around this time and the different arm positions of the sack help them find their self-soothing sweet spot.

My children are a bit too old to test swaddle transition gear, so I consulted our experts for this category, tested samples for materials quality, and took a not-too-distant walk down memory lane to when I was buying and trying this stuff with my babies.

In a traditional swaddle position, hands and arms swaddled down by the waist. The zip-off "wings" on this sleep sack allow a baby to keep their arms up by their face where many babies like to have access at this stage. With the adjustable wings, you can choose to have both arms up, both arms down, or one arm up and the other down. This is also crucial for use when babies get close to rolling to their sides, and having their hands and arms free is a must to prevent suffocation. 

If your baby likes to suck or gnaw on their hands through the cloth, it will stay damp for a bit but is fairly quick-drying. And the zipper position combined with the stretchy material allow for easy midnight diaper changes, which is a must for younger babies. The stitching began to come loose in a few places after a couple of machine wash and drying cycles.

The Kyte Baby Sleep Bag Walker had the softest material my baby and I tested, plus the unique walker design let her move and stretch in all directions.

Pros: Super soft, stretchy fabric; heavier weight but not suffocating; babies on the move will have the freedom to stretch out

Cons: Polyester fill, no footies, hang-dry only

Sizes: 6 to 18 months, 18 to 36 months, 4T

Fabric: 97% bamboo rayon and 3% spandex (outer shell), 100% polyester (fill)

My baby loved petting the extra soft bamboo rayon fabric of the Kyte Sleep Bag Walker and both doctors I spoke with said bamboo is a good material choice. The other 3% of the exterior material is spandex for a bit of stretch.

The Kyte is a moderately thick 1.0 TOG sleep sack with a polyester fill. Although polyester is a synthetic material that is not recommended for sensitive skin, it shouldn't be a problem in this case since the material does not make contact with a baby's skin.

My daughter wasn't walking when we tested this sack, but I loved how she could crawl without getting tripped up since the Sleep Bag Walker has a functional footless design. I put socks on her feet, but they always came off by morning, so that might be a drawback if you're in a cold climate.

The care instructions say hang-dry only, which is a big inconvenience if you only have one sack

At .2 TOG, the Love to Dream Light Sleeveless Sleep Bag makes parents secure in the knowledge that baby is covered and secure, but not smothered in too much material, even on the hottest nights.

Pros: Super lightweight, breathable, 100% cotton, two-way zipper

Cons: Baby couldn't crawl without tripping, neck tag is itchy and may need to be removed

I couldn't have been happier with the delicately crafted long and thin but roomy-in-the-leg design of the Love to Dream Light Sleeveless Sleep Bag. The .2 TOG cotton sack is designed for warmer temperatures and can be worn over just a diaper or a simple cotton onesie. It's super important that my baby has some coverage overnight, but nothing that will make her sweat and develop heat rash. This sleeveless bag did the trick.

A lightweight two-way zipper with plastic teeth and two coated zipper pulls ensure that no metal ever touches the baby's skin. I also loved that the zipper pulls are a bright color — different from the cloth or the zipper itself, which made for easier low-light bottom-access diaper changes in the middle of the night.

There were a couple downsides: The long, narrow fit tripped my daughter up a bit while crawling. There's also an itchy paper tag inside the neck, but it can be removed.

Since this sack is extra thin, I thought it might not be durable, but I was wrong. I followed instructions to wash and dry on the gentle, cold, low settings and saw no major signs of wear and tear.

The Gunamuna Sleep Bag Premium is extra thick and cozy at 2.6 TOG and feels almost as soft — and just as comforting — as velvet.

Pros: Super soft and cozy, 360-degree access with four zipper pulls and a shoulder snap

Cons: Polyester fill, zippers and pulls that match the fabric color make it hard to see them in low light

The extra-soft bamboo rayon shell of the Gunamuna Sleep Bag Premium feels cozy and comfortable enough for an extra-long winter's nap. The thick interior fill is polyester, which, as a synthetic, may not seem ideal, but received the go-ahead from our experts since the filling never touches the baby's skin.

The near-360-degree perimeter design zippers with four reversible zipper pulls offered the best bottom access for diaper changes out of all the sleep sacks we tried.

There's also an asymmetrical zipper access point on the left tank top side, and a two-snap entry point on the other side. I loved just lying my sleepy baby down and wrapping it around her. She could crawl a little bit wearing it, but thickness of the sack made her fall over.

And after a couple of washer and dryer cycles, there were no major signs of wear and tear. Although it's machine washable, you do need to use the low/gentle cycles. Major plus, though, you can use a machine dryer.

Baby Deedee Sleep Nest Travel: This little number didn't make the cut primarily because its outer shell is 100% polyester, and our experts advised against synthetic materials.

Halo Sleepsack Cotton Muslin Wearable Blanket: The original "sleepsack," this is a good, classic option, but the stitching started to fray more quickly than some of the others, so it didn't

Halo Sleepsack Swaddle Cotton Muslin: Again, the concept is great, but the fabric is prone to bunching up, and the stitching showed signs of breakage first thing out of the packaging.

Nested Bean Zen Sack Classic: I bought several of these myself and liked them with my second daughter, but I found out from the experts that it's best to stay away from sacks with weighted elements that can interfere with a baby's ability to breathe and move.

Each sleep sack had to stand up to four testing. We tested each sack for a week or more with my 1-year-old baby.

Material: Following advice from our experts, we looked for natural materials like cotton and bamboo over synthetics that could irritate sensitive skin. Dr. Susan Bard, a board-certified dermatologist at Vive Dermatology in Brooklyn, New York, recommends staying away from wool. Even though it's a natural material and there are many popular merino wool options, the fibers can be irritating to sensitive skin or eczema. We also looked for designs where fasteners like metal snaps or zippers won't touch the baby's skin.

Fit: We looked for a safe fit that allowed a healthy range of motion. Making sure we had our test baby wearing her correct size, we checked to see if she could roll over and even crawl a little bit without getting tangled in any extra cloth. We wanted to make sure each design allowed for enough hip freedom. According to the International Hip Dysplasia Institute, baby sleep products can be considered "hip-healthy" when they "allow the infant to actively flex the hips without excessive restraint while also allowing moderate to full hip abduction and external rotation." 

We checked to see if the baby could undo any of the fasteners herself. For this test, we gave the baby floor time in each sack and watched her behavior. We also checked to see if each sack had any weighted components. Dr. Rashmi Jain, a pediatrician with BabiesMD in Irvine, California, said that weighted sleep sacks are problematic if they inhibit the baby's ability to breathe easily. Also, while a baby is rolling, she said weighted components might make it difficult for them to adjust their position. Babies over 2 months old and close to rolling over, or already rolling over, must have use of their arms for safe sleep.

Everyday use test: We looked for ease of use in real-life conditions. We tested how easy or difficult it was to put the sleep sack on the baby in low light while she was wriggling or even crying and fussing, like whether I needed to fit her arms through holes, or if there were snaps that went around the shoulders. It mattered if the zipper was large and easy to use or tiny and the same color as the cloth. And it definitely made a difference if there was a reverse zipper design that allowed for an easy diaper change in the middle of the night without taking the entire sack off.

Durability and lasting softness: For this test, I checked for softness and how the material and stitching held up after a few uses. I also put each sleep sack through two machine washes and machine dryer cycles, except when the care instructions indicated hang-dry only.

The Academy of American Pediatrics (AAP) recommends a few essential conditions for giving your baby a safe sleep environment and reducing the risk of Sudden Infant Death Syndrome (SIDS).

Jain recommends making sure your baby is wearing the correct size sleep sack, since one that's too large or too small can "create unintentional entrapment of [the baby's] arms or neck."

There are more recommendations from the AAP about safe baby sleep, some concerning issues where personal choice comes in, like breastfeeding and bedsharing. You can check the AAP's safe sleep online resources and talk to your pediatrician to learn more.

Sleep sacks, also called wearable blankets, help your baby or toddler stay warm during sleep without exposing them to loose bedding that's known to increase the risk of SIDS. Plus, sleep sacks stay put, and keep baby covered all night.

There are no strict medical recommendations about when to use sleep sacks. Jain recommends swaddling until a baby shows readiness to roll and then transitioning to a sleep sack. For some babies, this can begin as early as 2 months of age. Riley Children's Health recommends sleep sacks for children under 1 year of age, but there's no harm in going longer. According to Jain, "If a baby is comfortable in a sleep sack and likes that snug feeling, they can stay until 2 years of age, or until they can't fit in the largest size available."

Some brands have sizing up to 36 months. A good rule of thumb would be to stop using a sleep sack by the time a toddler is in a big kid bed or is potty training and needs physical independence at night.

Yes! While a swaddle should never be used with an infant who is close to or already rolling over, a sleep sack is a safe options that allows a baby to use their hands and arms to reposition themselves when they roll over.

Picking the right sleep sack for the temperature is part of the AAP's safe sleep recommendations. Bard told me that choosing a natural, breathable material like cotton or bamboo "prevents overheating and absorbs any sweat which can lead to heat rash (miliaria)."

You can figure out the right one for your baby using our reviews and the TOG system. The Thermal Overall Grade or "TOG" is a unit of measurement that calculates how much heat a material holds.  Most sleep sack brands (all the ones we've recommended) come in varying levels of TOG for you to choose from according to the season, your home's temperature, and your baby's preferences. The higher the TOG, the warmer the sleep sack and vice versa. The lightest sleep sack we considered was 0.2 TOG and the heaviest was 2.6 TOG, though the scale technically goes up to 13.5 in the fabric manufacturing industry.

Dr. Susan Bard, a dermatologist with a fellowship in pediatric dermatology. Email interview March 9, 2021.

Dr. Rashmi Jain, a pediatrician in Irvine, California. Email interview March 12, 2017.

Natalie Willes, a certified baby sleep consultant and author. Phone interview February 23, 2021.

Safe Sleep Recommendations, American Academy of Pediatrics. Accessed March 2, 2021.

Baby Weighted Blankets: Are they safe? What You Need to Know, Healthline. Accessed March 5, 2021.

Sleep Safety, Riley Children's Health of Indiana University. Accessed March 11, 2021.

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