Your Guide to Infant Sleep Sacks: Styles, TOG Ratings, and Sizing

Your Guide to Infant Sleep Sacks: Styles, TOG Ratings, and Sizing

No matter the season, cold weather always calls for some hot cocoa and a cozy, plush blanket. Whether it’s for snuggling up inside while your kids jump in the gorgeous fall leaves, sitting on the sidelines while they play spring soccer, or as you all cozy up together watching the snow drift to the ground in winter, blankets provide warmth and a level of comfort to us all. So when I had my first baby, it was hard for me to lay her down to bed without the one thing we all need to sleep soundly at night. I quickly learned, however, that infant sleep sacks provide all the advantages that blankets do and more, keeping our infants safe from injury and harm as they sleep. So let's dive into the world of sleep sacks--from styles and brands to TOG ratings and proper sizing so that you know just which sleep bag is right for your baby!

Why Should I Use a Sleep Sack?

Blankets may seem harmless, but they can pose immense threat to young toddlers and infants. Due to a baby’s immature brain and inability to coordinate their hand movements, blankets can easily get pushed up and over their face and lead to suffocation.

In the past, it was very common to let babies sleep with blankets. Many older adults will even claim that parents today are overly cautious. I’m sure we’ve all heard the following argument: “Well you survived sleeping with blankets and you were fine.” But we know now, from years and years of research and heartbreaking infant deaths, that it’s vital that we follow safe sleep guidelines, which includes not using loose bedding. 

That’s why sleep sacks are one of the greatest inventions for parents today, allowing us to keep our babies snuggly and cozy at night while also keeping the material right where it should be--on your baby's body keeping them warm and not over their face. In turn, the risk of suffocation or infant injury is reduced drastically.

For toddlers and younger children, sleep sacks are still a great choice even when the fear of SIDS or suffocation isn't as big of a concern! This is because the sleep sack will always remain on their body, so you don’t have to worry about going in several times a night to reposition the blanket back over them when they inevitably kick it off again, then wake up and complain that they're cold. (Been there, done that!)

Blanket Alternatives

Swaddle Wrap/Swaddle Bag

Swaddle wraps (or swaddle bags) are one of the best blanket alternatives for newborns. They allow you to wrap your infants arms in place and provide them with the same secure feeling they had when in the womb. These often come with Velcro pieces that fold across the infant's chest to provide a tight and secure fit without the use of a traditional swaddle or blanket that could potentially come loose or unbound during the night.

For infants who don't like their hands to be bound to their side, some swaddle wraps, like the Love to Dream swaddle, have pouches for their arms that allow them to keep their hands by their face. These also have a zipper design, making it easier (and quieter) to change baby during the night!

Swaddle Up Love to Dream Swaddle

Swaddle bags are best for newborns and should not be used once your baby can roll over. Swaddle wraps/bags are designed to keep their arms, legs, and body secure, creating a womb-like environment and preventing the Moro reflex from waking them up as they sleep. If their arms are pinned down to their body and they roll over, they will be unable to push their face up and away from the mattress in order to breathe. So once they can roll, it's time to transition to another sleep bag style!

If you'd still like to provide your baby with the snug swaddle fit but your child has started to roll, you may want to try the Love to Dream transitional swaddle. This allows one or both arms to be out depending on preference while still providing that same swaddle feel.

Love to Dream Swaddle Up Transition Bag

Infant Sleep Sacks/Bags

Once your baby can roll, it's time to transition to a sleep sack! Sleep bags often have a looser fit than the swaddle wraps, giving a more "blanket-like" feel. They also allow for full arm movement and freedom, making them the safest option for babies once they can roll over and crawl! 

Let's check out some of the most popular sleep sack styles!

  • Long sleeve sleep bags: Long sleeve sleep bags are great for children that tend to run more cold and need extra warmth. They normally work best over a simple bodysuit, or you can place them over an infant sleeper as well for added warmth.

  • Sleeveless sleep bags: Sleeveless sleep bags are one of the most common styles you can find. They offer great versatility and can be used over any type of clothing. This allows you to use them for all seasons more easily than with a long sleeve sleep bag.

  • Weighted sleep bags: Weighted blankets are very popular because they provide deep pressure stimulation that can help improve sleep and reduce stress. In an attempt to provide these same benefits to infants, weighted sleep bags were created. These provide a slight weight to help encourage sleep and help your baby feel more relaxed. However, the AAP recently released a statement saying that they could possibly pose a hazard by preventing infants from being able to breathe effectively. So be aware of that and read thoroughly about the weighted sleep sack you're considering before purchasing it for your baby. 

  • Romper sleep bags: Romper-style sleep bags are perfect for older babies and toddlers. They have leg holes that allow them to walk or stand up, eliminating the frustration that comes when an older baby tries to get up and move in a traditional sleep bag. These are perfect for toddlers that may not be ready quite yet for a traditional blanket.

Kyte Baby Sleep Walker

Photo Credit: Kyte Baby

TOG Ratings

One of the main reasons we purchase sleep bags for our babies is to keep them warm. But how warm do we need to keep them? This is when TOG ratings come in handy! 

What is a TOG rating/score?

A TOG score is a value indicating a product’s ability to insulate and help retain heat. Parents can use this value to help them decide what sleep sacks will be best for keeping their child warm.

Infant sleep products normally range from a 0.2 TOG to about a 2.5 TOG. The higher the number, the better the product can insulate and help a baby retain their body temperature NOT taking into account the other clothing your child may be wearing underneath.

Paying attention to the TOG score when selecting a sleep sack for your baby is very important. Since infants struggle to maintain and regulate body temperature, babies can get too hot or too cold quickly. A sleep sack with too high of a TOG for your baby could result in overheating, which can actually increase SIDS risk. And of course, we don't want our babies to be too cold either!

It’s important to note that the TOG ratings are calculated under perfect conditions in a lab/factory setting. But there are variables that come into play as soon as you start using the product. As soon as you start using a sleep sack, its ability to insulate may go down with how much you use it or wash it (because the material or structure is no longer brand new, and things break down with use.) This is why it’s so important to buy really high quality products because not all brands are built to last. That’s why it's also essential that you look at the tag and follow manufacturer recommendations for how to wash AND dry the product so that the TOG rating remains accurate.

Camel Sleep Bag Copper Pearl

Copper Pearl Sleep Sack in Camel

Which TOG rating should I get?

Although it can be tempting to say that lower TOGs are for summer and higher TOGS are for winter, this is not accurate. If you keep your nursery at a consistent 70 degrees regardless of if it's winter or summer outside, you can use the same sleep bag all year round.

Here are some questions to ask yourself when picking out a sleep sack:

  • What temperature will the nursery be kept at regularly? (Look at the recommended ambient room temperature ranges provided by the company of the product you’re considering and make sure your nursery temperature falls within that range. Each company will differ slightly.)

  • Does my baby normally run hot or cold? (My son is always hot and sweaty during naps, while my niece tends to sleep much colder even though both of our homes have very similar ambient room temperatures. Therefore, I'd likely go with a lower TOG sleep sack.)

  • What is the baby going to be wearing underneath the sleep sack? (What a child wears underneath will matter. Long sleeve pjs underneath will automatically keep the child warmer.)

In general, a 1.0-1.25 TOG sleep bag will be sufficient for MOST people. A lot of research recommends that a safe ambient nursery temperature for babies is between 68 and 72 degrees, and most 1.0 TOG sleep sacks will recommend this range for this TOG.

Parents can adjust the child's clothing underneath accordingly depending on if the child is running hot or cold. In general, a baby will need one additional layer than you need to be comfortable in the environment. Parents should check on an infant's temperature when they’re sleeping by touching their neck, chest, or back to make sure it doesn’t feel too hot or too cold.

Sleep Sack Brands and their TOGS

Some brands only carry a single sleep sack while other brands will offer it in a few different TOG values. When deciding, make sure to pay attention to the suggested ambient room temperature for each brand. Although some brands may have the same TOG values for their products, the room temperature range to use it in may vary from brand to brand. This is because, although TOG testing is standard, some brands will do private research to determine more precisely the ambient room temperature recommendation for their particular product. This range will vary depending on the materials used for their product.

Whether you're looking for a lightweight, medium weight, or heavy weight sleep sack, here are some of the brands that carry each!

Lightweight/Low TOG Sleep Sacks

Nanit Sleeping Bag

Medium Weight/Average TOG Sleep Sacks

Woolino Organic Sleep Bag Dandelions

Heavy Weight/High TOG Sleep Sacks

  • Kyte Baby Sleep Sack: 2.5 TOG, 61 to 68 degrees F

Kyte Baby 2.5 Tog

*Note: This is NOT an all-inclusive list of infant sleep sacks. But these are some of the most highly recommended sleep bags currently on the market. You can shop all of our sleep sacks and swaddles online at

What if I still don't know which TOG rating will work best for my baby?

If you don't know which TOG to go with, consider going with the Woolino 4 Season Merino Wool Sleep Bag! Sleep sacks made with 100% Merino wool will not have a TOG score and are ideal for any and every ambient nursery temperature and work well for any baby, whether they run hot or cold! 

According to Woolino, the is because "Merino wool absorbs and releases moisture which creates a micro-climate around your baby when they wear our sleep bag. As wool absorbs moisture from the atmosphere a natural chemical process in the wool releases heat, which in turn warms the wearer. In cold weather the natural crimp in wool fibers creates tiny pockets of trapped warm air that act as insulators, holding in heat next to the body. This same process has a cooling effect in warm weather, as wool releases moisture it absorbs heat from the wearer and the tiny pockets of air created by the crimp in the fiber trap cool air and insulate you from warmer outside temperatures. As wool draws moisture away from the skin to evaporate, you feel cool and dry even in warm weather."

This makes the Woolino 4 Seasons sleep sack an excellent choice if you're not sure which TOG rating is best for your baby!

4 Season Baby Sleep Bag in Merino Wool Earth Woolino

Sleep Sack Sizing

Sleep sacks will normally range in size from small to large. Use the size chart for the sleep sack brand you've selected to determine which size will work best for your baby. In general though, watch for these things when you put your sleep sack on your baby. These things will normally indicate that the sizing is safe for your child.

  • The sleep bag is long and wide enough to give ample space for legs and hips.
  • Baby's head can not fit through the neck hole when the sleep sack is fully zipped.
  • Baby's arms cannot be pulled in through the arm holes voluntarily, where they could potentially get stuck and pose a hazard.

Here's an amazing fit test from Kyte Baby. Although this fit test is specific to Kyte Baby sleep sacks, it's a great guideline for sleep sacks in general.

Kyte Baby Sleep Sack Fit Test

Photo Credit: KYTE Baby

As parents, all we want is to provide our children with comfort and security as they grow. At the same time, we must do all we can to keep them safe from harm. When it comes to infant sleep in particular, it can be extremely stressful to know how to ensure this safety! Although it's easier said than done, try not to worry too much. Follow that momma instinct and know that all of us at The Baby Cubby are here for you! 

For more infant safety tips and guides, check out our blog at!

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