All About Baby Sleep Sacks

baby sleep sack

A baby sleep sack is also known as a sleep bag or wearable blanket. This is not considered a loose object in the crib so it is safe for keeping your little one cozy during sleep. It also works as a sleep cue to build positive sleep associations and improve sleep your baby!

This blog will address things like:

  • What is a baby sleep sack
  • Why should you use a baby sleep sack
  • When to start using a baby sleep sack
  • When to stop putting baby in a sleep sack
  • What should my baby wear under a sleep sack
  • Best sleep sack to help baby sleep

What is a baby sleep sack?

What is a baby sleep sack?

An important distinction to make is that a baby sleep sack is not the same as a swaddle. A swaddle can be used for the first few months of your infant’s life until they are showing signs of rolling.

You can read more about how to stop swaddling your baby in this blog.

Swaddling is referred to as the restraining of your baby’s arms in a blanket, swaddle pod, etc. Anything that gives their arms freedom (like a sleep sack for baby) is not the same thing as a swaddle! 

Swaddling is great to use to help them sleep while they still have their Moro reflex to keep them from startling themselves awake.

Some swaddles can be converted into sleep sacks though. For example, with velcro swaddles, you can leave their arms out and wrap the “wings” around their chest. This would not be considered swaddling! 

This is a great way to help your baby transition from a swaddle into a sleep sack while still keeping them cozy and using it as a sleep cue.

So what is a baby sleep sack? It is basically a bodysuit that is made out of blanket material that will zip up around your little one. 

It is what you will want to use as a safer alternative to a blanket in the crib while your baby is still at risk for SIDS. Research has shown that babies who sleep with blankets are 5x higher risk of dying from SIDS than those who sleep in a bare crib.

Babies who like to sleep in different positions (and can get themselves into those positions without assistance from parents) would benefit from using a baby sleep sack. They can safely sleep in any position they get themselves into so long as their crib is free of any loose objects.

Safe sleep guidelines as outlined by the AAP suggest that you keep the crib free of any loose objects including blankets, pillows, toys, etc. A tight fitted sheet from Kyte BABY and your baby is all that is needed in the crib!

You should continue to place baby on their back to sleep for their first year of life, and allow them to get into a comfortable position on their own. 

A blanket poses a suffocation and strangulation risk while babies are in their cribs as they can get entrapped in a blanket very easily; they do not have the coordination or strength to properly use a blanket at young ages.

Not to mention that most babies, even toddlers, will not keep a blanket on! So as parents, we have to keep covering them back up, wondering how we will ever keep them warm and comfortable enough to sleep well.

This is not a problem when using a baby sleep sack because it is wearable. They will sleep better and so will you!

Their wearable blanket will move with them instead of getting tossed to the side, will not restrict movement, and will keep them sleeping well all night long.

A baby sleep sack can be used as soon as one fits your child well without being able to pull the neck of the sleep sack up around their face. 

Both a swaddle and sleep bag are great tools for sleep for your little one, they are just used for different stages of their development!

Why should you use a baby sleep sack?

Why should you use a baby sleep sack?

As parents, we want to keep our babies as comfortable as possible! This will keep baby at a comfortable temperature all night long.

Using a baby sleep sack can decrease the risk of SIDS because it decreases the risk of your baby overheating. They are also designed to fit well on your baby so that their face does not get covered and risk suffocation.

They also improve sleep for your baby. Sudden temperature changes can wake them often during the night, so by using a baby sleep sack, their temperature will stay nice and regulated all night long.

There is no risk of kicking off the baby sleep sack like a blanket!

Reducing the risk of your baby getting cold at night will result in fewer wake-ups for them and you.

This ensures baby will sleep safely without the risk of getting tangled up in a blanket, risking suffocation or strangulation. 

A baby sleep sack can reduce the risk of little limbs getting stuck between the crib slats. Since bumpers are not recommended for safe sleep, even mesh ones, this is an added bonus!

WebMD reports over 10,000 crib-related injuries happen each year, mostly from little ones climbing or falling out. A sleep sack or sleep bag walker can make it much more difficult for your baby or toddler to climb out of their crib.

You can read more about safe sleep in this blog.

Using a baby sleep sack as part of your pre-sleep rituals builds positive sleep associations for your baby. When they have a consistent routine with the same steps each time before sleep, they learn to expect sleep is coming which means they will accept it more.

You can lay the sleep sack out in the crib, put your baby in, then zip them up! Essentially just like tucking them in with a blanket, without the worry of unsafe practices.

That means fewer sleep battles! Win-win. If you are transitioning from the bassinet to the crib, and then the crib to a bed, the sleep sack or sleep bag walkers for toddlers will help to ease that transition.

A baby sleep sack will create a safe and familiar sleep environment for your baby. That means when you travel or sleep outside of the home, you can bring their sleep bag as a reminder from home and continue to sleep well even though they are in a less familiar place. 

Kyte BABY sleep bags also help those middle of the night diaper changes! The sleep bags feature a double zipper, so you can unzip from the bottom to disturb baby even less during the night. Then you both can return to sleep a lot faster!

According to Red Nose, research shows that using a baby sleep sack has great benefits such as:

  • Reducing the risk of bedding covering the baby
  • May slow down rolling to belly too early
  • Promotes back sleeping
  • Keep baby’s temperature at a consistent level while sleeping since infants do not regulate their temperature well on their own

Fun fact: baby sleep sacks first appeared in the 1960s in Finland in the Baby Box; this is a box that was designed in the 1930s to give all children an equal start to life. Finland’s infant mortality rate is one of the lowest in the world!

The Baby Box provides a safe, separate sleep surface for infants and the sleep sack ensures no loose objects are in the box with baby!

You can check out this great chart from Statistics Finland to see the rates of SIDS and how dramatically they’ve declined.

This abstract confirms that a sleep sack is a safe/safer alternative to using blankets in the crib.

According to this study, “sleeping bags might provide a more constant temperature profile, while other bedding conditions may lead to significant variations of temperature pattern.”

When to start using a baby sleep sack?

When to start using a baby sleep sack

You could technically use a baby sleep sack from birth so long as it fits well! However, most babies will sleep best when they’re swaddled in those early days which is not the same as  sleep sack.

A swaddle will restrict arm movement to decrease the risk of their Moro reflex from waking them up. A sleep bag does not restrict arm movement.

Most sleep bags are designed to fit babies who are 8-9+lbs, however, you will want to double-check the fit of the sleep bag around their neck to ensure it is not too loose!

When to stop putting baby in a sleep sack?

There is no hard and fast rule for this one. Since a sleep sack can ease all the major transitions in your baby and toddlers life, it is very easy to continue using one until your child asks to sleep without it or they outgrow the largest size!

Kyte BABY’s sleep bag walkers are generously sized, all the way up to 4T. Most kids can wear their walker a lot longer than you’d expect!

Most of the time, a sleep bag will become your child’s comfort item and something they love to sleep with. You do not have to rush the transition out of the baby sleep sack!

Since the AAP recommends keeping the crib bare, regardless of age, it is best to continue using one while your baby is in the crib. You can still use the baby sleep sack or sleep bag walker in a regular bed if your child has difficulty keeping blankets on or prefers to use the cozy sleep bag instead of a blanket!

So is it safe to use a baby sleep sack? Absolutely! As long as you are aware of their body temperature so they are not overheating, the sleep bag is properly sized, and the sleep bag does not have any extra parts that could pose a danger to your little one.

To make sure your sleep sack is properly sized, you will want to make sure that baby cannot wiggle down into the sleep bag, potentially getting trapped or that you cannot lift the sleep bag over their face from the neck.

This study by Dr. Rachel Moon reviewed infant deaths using wearable blankets and concluded that “Reports of sudden unexpected death in swaddled infants are rare. Risks can be reduced by placing infants supine and discontinuing swaddling as soon as an infant’s earliest attempts to roll are observed. 

Risks can be further reduced by removing soft bedding and bumper pads from the sleep environment. When using commercial swaddle wraps, fasteners must be securely attached.”

Therefore a sleep sack is a safe alternative!

What should my baby wear under the sleep sack?

What should my baby wear under the sleep sack?

To decide what your baby should wear under the sleep sack, it’s important to know the ambient room temperature and what TOG or thickness your current sleep sack is. Kyte BABY offers 3 different TOGs: 0.5 (thinnest), 1.0 TOG (more universal for all temperatures), and 2.5 TOG (for colder climates).

To read more about TOG, check out this blog!

  • 0.5 TOG is appropriate for room temperatures of 74-78°F (23-26°C)
  • 1.0 TOG is appropriate for room temperatures of 69-73°F (21-23°C)
  • 2.5 TOG is appropriate for room temperatures of 61-68°F (16-20°C)

Here is another good read on figuring out what TOG sleep sack to use for your baby.

A good rule of thumb is to put your baby in a layers that would be comfortable to you, with maybe one extra layer. So pyjamas and an appropriate TOG sleep bag is the perfect sleep combination for your baby!

Each baby is unique and may prefer to sleep with more or fewer layers. You will want to make sure that your little one is not sweating, does not have damp hair, does not have a heat rash or red cheeks, and is not breathing heavily as those are all signs of overheating.

Babies who are too warm while sleeping will be more restless and wake more often whereas babies who are too cold may become lethargic and harder to rouse. 

Babies have protective factors in place to wake often during the night, but they can return to sleep if they are comfortable or else they will signal to let you know they need something!

If you find your baby is waking more often and it is not because of body temperature, you can check out this blog about baby sleep regressions.

Once you know what the room temperature is where your baby is sleeping, then you can decide on a TOG for your sleep bag and how to dress them under the sleep sack.

It is most common to use a onesie, footie, romper, or two-piece pyjama sets under a baby sleep sack. Usually one layer of clothing under the appropriate TOG of the sleep sack is sufficient!

However, if you have a 1.0 TOG sleep bag and it is colder than 69°F in the room, you can add an extra layer of clothing, like a onesie and a footie if needed instead of purchasing a 2.5 TOG sleep sack.

If you are unsure if your baby is too hot or too cold, check the back of their neck. If their neck is cold, you can add an extra layer of clothing. If their neck is sweating, you can remove a layer of clothing or use a lower TOG sleep bag.

Never judge by their hands or feet as the circulation to those areas is poor and is not indicative of body temperature.

You also never want to put baby in a sleep sack and then use a blanket on top of them as that puts them at major risk for overheating.

This study discusses overheating and it’s relation to SIDS. Furthermore, this study also reported, “Temperature increases were associated with an elevated risk of SIDS in the summer, particularly among infants who were black, 3 months old and older, and living in the Midwest and surrounding northern regions.”

What is the best sleep sack to help baby sleep?

What is the best sleep sack to help baby sleep?

The best sleep sack is one that is appropriate for the room temperature where your baby sleeps, one that is appropriate for their skin (for example, not made of synthetic materials or treated with chemicals), and one that fits well!

Kyte BABY sleep bags are high quality sleep bags made from bamboo material. It is the softest fabric and also 3° cooler than cotton. 

The bamboo material is breathable which is key in preventing baby from overheating. 

The material also absorbs and evaporates humidity better than any other material on the market, keeping your baby as comfortable as possible while they sleep.

By choosing bamboo, you choose a sustainable resource! It is also hypoallergenic so great for sensitive skin.

The difference in Kyte BABY sleep bags versus other similar products on the market is the zipper design; our sleep bags offer a curved, dual zipper design which allows for extra comfort for your baby and ease of use for parents during the middle of the night diaper changes.

The zipper garage is also convenient for keeping the zipper “out of sight, out of mind” for adventurous babies/toddlers who may want to unzip their sleep bag!

Kyte BABY sleep bags are also sleeveless which allows for more circulation, another feature in preventing overheating. 

The sleep bag is also roomy which protects your little one's hips for optimal hip development, but closed on the bottom which protects little limbs from getting stuck in crib slats.

From a mom, “I LOVED the sleep sacks from Kyte BABY over her pjs’ when I thought she needed another layer. They are big and roomy like a blanket but safe for sleeping!” - @katyroseprichard

Because Kyte BABY offers different thickness of sleep bags, there’s an option for every family and climate available. Not to mention all the different baby sleep sack patterns!

By investing in a good quality sleep sack, you will get more than your money’s worth back in good sleep for you and your little one!

What other moms are saying about Kyte BABY sleep bags…

“We were just gifted one of these sleep bags and it was the first time since we stopped swaddling her that she slept as good as she did when swaddled!” - @momomomma.v

“I just wanted to say thank you so much for an amazing product. I am a new follower, but not a new fan. My three-year-old has long since outgrown her sleep sack, but it is her constant companion. We don’t leave the house without it, ever. It has held up perfectly as she drags it through life.” - @ljdw176

How to choose a baby sleep sack?

You will want to choose a size that fits your little one currently. While you can size up for a lot of baby items, a sleep sack is not one of those items. 

The sleep sack may be too long but should fit well around their arms and neck.

You’ll also want to refer to the above section for choosing a sleep bag that is the appropriate thickness. For warmer rooms, you will choose a lower TOG. For cooler rooms, you will choose a higher TOG.

You may even use a different TOG for naptime than you do at bedtime. You may have a different TOG for baby sleep sack winter or baby sleep sack summer.

Should you use a baby sleep sack with sleeves? For circulation, it’s beneficial to choose a sleep back without sleeves as that can pose a risk for overheating. You will also want to make sure the baby sleep sack does not have a hood!

It is helpful to choose a sleep sack that has a double zipper or inverted zipper to make diaper changes easier in the middle of the night.

When it comes to our little ones, safety and comfort are huge priorities for us as parents. If you wish to provide your baby with a good night’s sleep without having to worry if they’re too hot/too cold, or concerned about safety, then a baby sleep sack will meet that need!

AUTHOR: Ashley Olson is a certified paediatric sleep consultant, owner of Heaven Sent Sleep, and passionate about helping new parents, experienced parents, desperate and sleep-deprived parents form healthy sleep habits for their children.

She has over 3 years of experience in working with families and has completed over 150 hours of coursework plus continuing education related to infant and toddler sleep. The focus of her work is on fostering a routine that grows your bond with your child while improving their sleep habits. She specializes in custom sleep plans and one on one support in changing sleep practices!


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