The Ultimate Sleep Sack Guide

  • By: The DIG for Kids
  • Time to read: 7 min.
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Are you confused about what a sleep sack is for? Check out this guide to learn more about why they are a must-have for your baby and how to choose the best one!

Have you ever seen a picture of a baby sleeping in a zippered cloth bag with arm holes and wondered what it is? A sleep sack is a wearable blanket for babies. It is used in place of loose blankets and sheets as a safer option for young babies and toddlers. 

In this article, we will help you understand what a sleep sack is, how to choose the right one, and why they are a great thing to have as a new parent.

What is a sleep sack? 

A sleep sack is a wearable blanket often worn by babies and toddlers to sleep in. It is usually made of soft, loose cloth and features a full zipper front and arm holes so that your baby can wear it over pajamas or other clothing. 

Does my baby need a sleep sack? 

While a sleep sack is not an absolute must, it is a great thing to have. It adds an extra layer for warmth and comfort while they are sleeping while still keeping them safe. 

The American Academy of Pediatrics recommends that babies do not sleep with any loose blankets until they are over the age of 1 because of the risk of SIDs. Anything loose in your child’s crib while they are sleeping is a suffocation risk at this age. 

That means that sheets and comforters are not an option for your baby for quite a while, so that is where a sleep sack is a great way to bridge the gap. 

Can babies wear sleep sacks when they roll over?

You don’t need to worry about taking away a sleep sack once your baby is rolling. The generous, roomy fit of a sleep sack allows your baby to have plenty of room to move around in the night. 

Whether your baby is rolling, crawling, sitting up, or standing, a sleep sack that fits properly won’t hinder their movement and is perfectly safe. 

How should a sleep sack fit? 

There are many types of sleep sacks on the market. Dozens of different brands make different styles with all kinds of materials and weights to meet any need. 

For younger babies who may be moving less or just transitioning from being swaddled for sleep, a tight-fitting sleep sack or sleep pod is a great option. This allows them to feel the comfort of being snug in something while still having the freedom to move their arms.  

When you decide it’s time for your child to wear a regular sleep sack, the fit is generally oversized and long. This is because it is replacing blankets and bedding, so a generous fit is ideal. Just make sure that it fits comfortably at the top and can’t slip over their head.

Most companies offer various sizes in their sleep sacks and provide height and weight minimums and maximums for each size. This should help you choose the right sleep sack for your baby. 

Do I need more than one sleep sack?

It’s best to have at least two sleep sacks that are in your baby’s current size. This is because you want to make sure you always have one clean in case you have to wash one unexpectedly due to spit-up or an accident. 

Another reason it’s helpful to have more than one sleep sack is if you live somewhere that it gets cold at night. If you do, you may want to invest in a sleep sack that is a heavier weight for the cold weather season and a lighter one for warmer temperatures too.

Do babies like sleep sacks? 

Most babies like sleeping in a sleep sack because they are soft and comfortable. It can be a great sleep association to introduce early on that helps your baby realize that it’s time to wind down for a nap or bedtime and it provides comfort and warmth. 

If your child is not a fan of layers or runs very warm, a sleep sack may not be the best option for them. You can try a few different types to see if you can find a style that is the right weight for them or you may choose to let your baby sleep without a sleep sack if you wish.

What should my baby wear under a sleep sack?

How you dress your baby for sleep under a sleep sack will vary greatly based on a couple of things. Important things to consider are the temperature in the baby’s room and whether your baby runs warm or cold. 

On a warm night, a baby could sleep in just a onesie in their sleep sack. On a more moderate or cool night, they would likely be comfortable in long-sleeve footed pajamas under their sleep sack. If it’s especially cool where you are, you could add another layer under their pajamas too.

Most major sleep sack manufacturers use a TOG (Thermal Overall Grade) rating system to rate the weight of their sleep sacks. This rating describes how much the material of the sleep sack insulates.

The universal TOG system is helpful when selecting the right sleep sack depending on what the ambient temperature will be in the baby’s room. It also lists recommendations of what layers to dress the baby in underneath the sleep sack depending on temperature.

How long do babies wear sleep sacks?

The length of time that your baby wears a sleep sack to bed is largely about preference and what works for your family. Some brands make sleep sacks in sizes that will fit up to a 3-year-old. 

Once your baby reaches age 1, you can make the choice to continue putting them in a sleep sack or transition to traditional blankets and bedding. It is generally considered safe to do so anytime after the first birthday depending on your preference and what your child likes. 


Sleep sacks have become more and more popular over the years, I know I used one for my little boy until he was about 3 as he was always kicking of his sheets. Here is a run down of our top sleep sacks.

HALO Sleepsack 100% Cotton

HALO SleepSack, 100% Cotton Wearable Blanket, Swaddle Transition Sleeping Bag, TOG 0.5, Huggy Bears, Small, 0-6 Months

These Halo sleep sacks come in a HUGE amount of different patterns and a range of sizes. They are 100% cotton so super soft and should last for many washes. They claim to be many hospitals swaddle of choice. This one is 0.5 TOG so perfect for warmer weather and big enough to put cosy thick PJS under for colder nights.

100% CottonWe couldn’t find anything wrong with this product
Double zipper for diaper change
No sleeves so won’t overheat
Huge range of patterns
HALO SleepSack, 100% Cotton Wearable Blanket, Swaddle Transition Sleeping Bag, TOG 0.5, Huggy Bears, Small, 0-6 Months
  • Use over regular sleepwear to take the place of loose blankets.
  • 100% Cotton. TOG: 0.5. Size preemie fits birth-5 lbs.; size small fits 10-18 lbs.; size medium fits...
  • Unzips from the bottom for easy diaper changes. Generous sack design allows room for kicking, but...

Baby Deedee Polar Fleece Sleep Sack Bag

Sleep nest Fleece Baby Sleeping Bag, Mocha Heather, Medium (6-18 Months)

These Baby Deedee sleep sacks come in a really cosy fleece material and comes in a range of colours and sizes. They can be tumble dried on a low heat too which is handy and have a quick release shoulder strap design so very easy to get and off quickly if needed and you don’t have to battle to get your littles ones arms through a hole. This one is a mid weight design at 1.2 TOG. Very roomy inside. They also have a wide reverse zipper.

Shoulder Studs for easy openingSome people have found them too long
Cosy fleece material
Range of colors
Camp tumble dry on low
Sleep nest Fleece Baby Sleeping Bag, Mocha Heather, Medium (6-18 Months)
  • COZY BABY SLEEPING SACK: Comforting cocoon shape, promotes sleep for the whole family. Great...
  • UNIQUE SLEEPING BAG: Exclusive shoulder straps make placing a sleeping or standing baby in the sleep...
  • HIGH QUALITY BABY SLEEPER: Give your baby or toddler ultimate comfort. 100% soft premium Polar...

HALO Micro-Fleece Sleepsack Swaddle

Halo Sleepsack Micro-fleece Swaddle, Soft Pink, Xx Small, Size: Preemie

We love these sleepsacks as they have a 3 way adjustable swaddle system where you can have babay arms in, hands to face or one or both arms out. This is really handy if you find baby scratching there face in the night or you want to encourage them to self soothe with their hands. A 3.0 TOG sleep sack so might be more suitable for smaller babies or colder climates. Comes in a range of sizes and colors

3 way adjustable swaddle strapLining up the velcro in the dark might be tricky
Choice of sizes including preemie
Range of colors
Up zipper access
Great for newborns
Halo Sleepsack Micro-fleece Swaddle, Soft Pink, Xx Small, Size: Preemie
  • 2-in-1 adjustable swaddle that allows for swaddling arms in or arms out for baby's comfort; 100%...
  • Used by over 1,000 hospitals nationwide as their product of choice for teaching parents safe sleep...

Woolino 4 Season Baby Sleeping Sack with feet

Woolino Baby Sleep Bag With Feet Opening Merino Wool Walker Baby Sleeping Bag 18-36 Months Butterfly

If your little one is up and about you might want to consider something with feet holes so they are not trying to waddle about in a sack! These are great and with an Australian merino wool lining – 100% natural it is designed to regulate the body temperature so is a 4 seasons sack. Has a zipper at the bottom for diaper change without being removed.

Regulates body temperatureMore expensive than others
Feet openings for mobility
Goes upto size 3-4T
Up zipper for easy access
100% Natural Fabrics
Woolino Baby Sleep Bag With Feet Opening Merino Wool Walker Baby Sleeping Bag 18-36 Months Butterfly
  • 100% Natural, made of premium luxuriously-soft hypo-allergenic Australian Merino wool; GOTS...
  • No need to buy different TOGS. Optimal weight Merino lining regulates temperature so it can be used...
  • Foot openings allow for mobility when child is awake. Generous size so child can tuck feet in when...