The Ultimate Sleep Sack Guide


Jul 6, 2023

If you are new to the baby world, you may be wondering why the heck babies need all this stuff for sleep!! Can’t they just lay on a mattress and go to sleep? (Yes and no!)

Today we’re talking all about sleep sacks! Consider this your ultimate sleep sack guide to understanding what they are, how to pick the right one, and if your baby can sleep without one! Over on the Little Z’s Sleep podcast we’re covering this as well! Click here to listen in!

So perhaps you are holding a newborn and they’re swaddled so perfectly, or you have a baby and they are in a sleep sack, but you’re wondering, “Do they really need this thing?

I want to be perfectly honest with you that I am a minimalist when it comes to baby products and baby gear. In fact, when I was pregnant with my first daughter, Ellie, I literally Googled minimalist baby registry, because I was certain that I was not going to have a daycare in my living room. 

And now while that did kind of happen, you do somehow end up with the paraphernalia all over your living room. The thing is, your baby doesn’t need ALL the things out there. 

In fact, I am a super traditionalist when it comes to setting your baby’s room up. That’s a completely different topic, and we can talk about nursery setup, but I love a good white noise machine. I love a good safe crib setup, and having a dark sleep space with a sleep sack. It’s all you need!! 

Sleep sacks honestly were one of those things that I didn’t ever hear about until I had a baby. Now I don’t know why you would hear about it unless you had kids. But sleep sacks were one of those mysterious products that I kept thinking, “do I really need this?!

I’ll also set the stage for you. At the time when I had my first daughter, we lived in Louisiana. So it was pretty much warm or hot all year long. And I thought, “There’s no way that my kid needs a wearable blanket in our house!!”

Obviously, we had air conditioning. But my daughter’s room had a gigantic window – I’m talking a floor to ceiling window – that was beautiful when we bought the house. I never thought about the fact that when I had a kid it would be harder to keep control of the air conditioning, or the lightness and the brightness of the room. But here we are. 🤣

So here I am with my first baby. She is living in a very warm climate and there’s a very large window that just bakes her room all day long. 

So did I really need a sleep sack? 

The answer is yes. 

But what I found out was that I needed a sleep sack that had a thinner, lighter fabric based on the weather where we lived.



First, you will need to figure out the TOG (Thermal Overall Grade) that you need. When you are looking at a TOG chart, the lower the rating (the lower the number), the lighter the fabric is. The higher the number, the higher the TOG – meaning the more insulated, the more padded it is. 

So lower number = lighter fabric. Higher number = thicker, insulated padded fabric. 

So when it comes to understanding what TOG you need, a lot of the time, it depends on what environment you live in. You could live in a climate or your home could be a cool 70 degrees each night, but if your home is drafty, and the windows leak a little bit, or the house doesn’t hold the temperature as well, you need to understand if it is warmer or cooler. 

So if you’re wondering what kind of sleep sack or TOG your baby needs, I really can’t give you a standard suggestion. This does depend on your climate. 

For my girls, I typically used muslin or light cotton sleep sacks because we live in a warmer climate, and to be perfectly honest, I did not use sleep sacks for very long. That’s because, like I said, I’m kind of a minimalist. I stopped buying sleep sacks at 6 months old, but a lot of people keep them up into the toddler years. Which is perfectly okay, too!!



When you’re looking at the wild world of sleep sacks, there are some brands out there like Woolino. These are expensive… they’re about $100 per sleep sack. 

However, they are sleep sacks that grow with the child. So you can have them from four months old all the way up till over a year old and that way you don’t have to keep buying the next size and the next size as your baby grows. 

If you are looking for a specific brand, like the Halo Sleep Sack, for example, then some of these will be based on the age and the size of your child.. I actually really liked the options where the sleep sack was built into the swaddle so when you transition to arms out, it gives you two products in one.



When you look at a sleep sack, you may be wondering why you can’t just give them a blanket. This is because it’s not safe for babies under 12 months old to have any loose items in their crib. So we offer a sleep sack (or a wearable blanket) because it is a blanket, but it’s not unsafe. 

It is not something that you need to worry about covering their face, it’s not possible. It keeps them warm, comfortable and cozy in their crib, but you do not need to worry about a loose item coming on top of their face and obstructing their breathing. 

Around 12 months old you can introduce a lovey or a stuffed animal for your baby. But still, they can’t really use a blanket to manipulate it and use it to cover their body. You could offer them a small blanket especially if they like to suck on it, as that can be soothing for some kids. 

But even for toddlers, the reason that you will see extra large sleep sacks and the reason that I have a whole blog dedicated to toddler sized sleep sacks is because your toddler cannot keep a blanket on them. 

When you move your child to a big kid bed at age 3, this is an opportune time to get out of the sleep sack and use blankets.



So for the first 3 years of your baby’s life, this is how long you could use a sleep sack.  

For the first 2 months, they’ll be swaddled and then beyond that, they can use a sleep sack to keep them comfortable and to keep them cozy in their crib, but it isn’t necessary to use them forever. When it’s time to move to a big kid bed at 3 years old, you may want to go ahead and transition out of the sleep sack and use sheets, blankets, quilts or whatever you want to use.



One of the reasons I also love sleep sacks is for kids who nap at daycare or at someone else’s home where it’s not their nursery environment during the day. A sleep sack is an amazing cue for sleep. 

Now this can really be for anywhere, even at home, but if your child is napping at daycare, you can ask the daycare teachers if you can bring a sleep sack and have them zip your baby up in a sleep sack for their nap. 

You can also ask if they’re a toddler. Sometimes they will, sometimes they won’t, especially if they’re on a cot, but there’s no reason you can’t simply ask – the worst they could say is no and then you can have them bring a little lovey. 

However, for many daycare babies, their naps are short and it’s often because of the environment, right? It’s bright, it’s loud, everyone naps at different times. So it’s not the ideal environment for sleep. But babies are smart and they do adapt. 

But that little leg zip when you’re zipping up the sleep sack is such a powerful cue. So many families have told me that as they’re zipping their baby up, they start to yawn or rub their eyes. 

You’ve heard of Pavlov’s theory, right? Like you hear the sound or something happens and you know, we’re about to go to bed. So having a sleep sack for a baby who is in daycare, I like this opportunity to create a routine and to create a cue for them that once you’re zipped up, now it’s time for sleep. 

For a daycare family who is struggling with having their baby nap, a sleep sack can be a game changer for you. If you’ve ditched it, and if you’re a daycare family struggling with short naps, you may want to consider bringing it back and using one for daycare and one for the house so that your baby can understand that motion of being zipped up means that it’s sleepy time.



Another reason I love sleep sacks is that it can help prevent your child from climbing out of the crib. I can’t guarantee this, but if you have a child wearing a sleep sack, sometimes they cannot lift their legs up and over the crib rails and it may help them to stay in the crib. 

If they are getting smart and clever and they’re unzipping themselves, maybe taking their diaper off, it’s becoming a whole thing, all you need to do is put the sleep sack on backwards. Now they can’t unzip themselves because the zippers are in the back. 

Hopefully this sleep sack guide gives you a little more clarity on what they are and which ones are right for you and your family so you can keep your baby happy, healthy, and well rested by keeping sleep a thing!!



Let's talk about sleep sacks! Here I give you a full sleep sack guide for your baby!

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