What Should A Baby Wear Under A Sleep Sack?

what should a baby wear under a sleep sack

Table of Contents

As a first-time parent, the question of what your baby should wear under the sleep sack can be a bit daunting. After all, you want to ensure that your little one is comfortably and warmly dressed. But what should a baby wear under a sleep sack? Let’s find out!

In this blog post, we’ll explore the different clothing options available for babies under their sleep sacks.

Why Do Babies Need Sleep Sack?

what should a baby wear under a sleep sack

Sleep sacks are babies wear, designed to keep your baby warm while they sleep comfortably. Typically made from a soft, breathable material like cotton or flannel, sleep sacks also provide some protection against Sudden Infant Death Syndrome (SIDS). Sleep sacks can be used in both cribs and bassinets.

When it comes to what a baby should wear underneath their sleep sack, the most important thing is comfort. It’s best to choose lightweight fabrics that will keep your baby cozy without making them too hot. Cotton onesies with no feet make great base layers for babies to sleep in cooler climates. If you’re looking for something warmer, opt for footed pajamas or fleece jumpsuits instead. Sleep bags and Bassinets are also great options for keeping your baby’s sleep time warm.

Read More: 4 Month Sleep Regression Or Teething

What Should A Baby Wear Under A Sleep Sack?

Sleep sacks are great because they’re designed to keep your baby warm dress your baby for sleep properly, to secure without having the worry of them becoming tangled or too hot. But what should you put under your baby’s sleep sack for extra warmth and comfort? Let’s take a look.

Layering Up

When it comes to dressing babies for bedtime, layering up is key. The layering process starts with a onesie (also known as an undershirt). A onesie is a perfect foundation for pajamas because it’s not too thick or too thin and provides just enough coverage.

You can choose from long sleeves or short sleeves depending on the temperature in your home. Some babies are comfortable in short sleeve onesies and footed pajamas or a cotton sleep sack, while others may need some additional warmth.

Adding A Sleep Gown

The next layer to consider is a sleep gown. Sleep gowns are great for newborns who tend to kick off their blankets during the night—the snug fit of the sleep gown prevents them from getting uncovered during sleep time.

Plus, they make diaper changes easier since you don’t have to completely undress your baby every time they need to be changed! It’s also important to note that some babies may find long sleeves uncomfortable at night, so choosing a sleeveless option can help prevent them from getting overheated.

Read More: What Time Should My Baby Wake Up In The Morning?

 Putting On The Sleep Sack

Once you’ve layered up correctly with both undershirts and sleep gowns (if necessary), it’s time to put on the sleep sack itself! Sleep sacks come in various sizes and materials, such as merino wool or muslin cotton blends.

Be sure to select a size that fits snugly but still allows freedom of movement—too loose could lead to your baby getting tangled up in it during their slumber! Finally, add an extra blanket over the top if needed; this will provide additional warmth without risking suffocation or overheating due to layers of fabric around their neck and face area.

For Colder Months

If the temperature drops during colder months, you may need an extra layer of protection for your baby while they sleep. In this case, consider adding a lightweight long-sleeve shirt or fleece sleeper underneath their sleep sack. Be sure not to go overboard with heavy materials such as wool or down as these can cause overheating and also make it difficult for your baby to move around in their sleep sack.

In Warmer Months

During warm weather months when baby’s room temperatures rise, you may want to consider dressing your baby in light layers such as a cotton undershirt and lightweight pants or shorts instead of a onesie or footed pajamas. This will help keep them cool while they’re sleeping without having too much bulk that could make them uncomfortable in their sleep sack.

Read More: How To Stop Baby Waking At Night Out Of Habit

Benefits Of Dressing Your Baby Underneath Their Sleep Sack

what should a baby wear under a sleep sack

The main reason for dressing your baby in a onesie or pajamas underneath their sleep sack is to help regulate their body temperature. Babies cannot regulate their own body temperature yet, so you want to make sure that they are wearing enough layers to stay warm without becoming too hot or uncomfortable. You may also need one or two more layers if the room is cold.

For example, if the air conditioner is running during warmer months or there are drafts in winter months, then you might need extra layers on top of the onesie or pajamas to keep them warm.

The best fabric for this type of clothing should be lightweight and breathable—such as cotton—so that your little one does not become too hot during the night. Also, make sure whatever clothes you choose are soft and non-irritating against their skin; babies have very sensitive skin so avoid materials such as wool or polyester.

Using a Blanket instead of Clothing Underneath a Sleep Sack Is Not Recommended. It’s important to remember that using a blanket instead of clothing underneath a sleep sack can be dangerous for your little one because blankets can come loose during the night and cover your baby’s face.

This is why it’s recommended by pediatricians that babies do not use loose blankets in their crib until they reach 12 months old; this will reduce the risk of SIDS (Sudden Infant Death Syndrome).

Instead, opt for something like a wearable blanket (a type of sleeping bag with armholes) once your baby reaches 6 months old as these have been proven safer than traditional blankets and can also help regulate their body temperature better than loose blankets.

Read More: How To Keep A Baby Warm At Night


Dressing your baby in a onesie or pajamas underneath their sleep sack is an important part of helping them regulate their body temperature at night. Be sure to select lightweight, breathable materials such as cotton which won’t irritate their skin, and opt for fitted clothing instead of a blanket that can come loose during the night. Doing this will ensure your little one is comfortable without overheating, no matter what the season.

Read More: How To Keep Your Baby Safe While Sleeping

More Of The Same Category​

Jenny Chaines

Jenny Chaines

Having the perfect bassinet is something that every mother wants for her child.
I've been doing my own due diligence since the day I knew I was pregnant and I'm here to let you in on the ins and outs of it all...

About Me

Having the perfect bassinet is something that every mother wants for her child.
I’ve been doing my own due diligence since the day I knew I was pregnant and I’m here to let you in on the ins and outs of it all…

Recent Posts

Co-Sleeping Bassinet