What Should Your Baby Wear in a SNOO (Ultimate Guide)

2 baby sleepwear

You’ve recently become a proud owner of a SNOO Smart Sleeper Bassinet for your newborn. Congrats! Your next step is to decide what your baby should wear in your new or used SNOO. Should you opt for the cute onesies you got as gifts from your baby shower? Or, do you stick with the SNOO sacks that come with the bassinet? Read on to find out. 

What Clothes Your Baby Should Wear in SNOO

The SNOO sack is designed to help your baby sleep well in the SNOO smart bassinet using the swaddling technique. If the room temperature is right, your baby will be comfortable only wearing a sack. But, you can dress them in a onesie under the sack if your baby gets cold easily. 

How to Know If Your Baby is Warm Enough in the SNOO

When you purchase a SNOO Smart Bassinet, you’ll discover it comes with its own set of rules regarding your baby’s sleepwear! This may be confusing when you’ve been following conventional ideas for what your little one should wear to keep warm at nighttime. 

The same signs apply when knowing if your baby is warm enough in a SNOO as for any other cribs. These include your baby settling down without niggling and showing no signs of overheating or being too cold. 

A baby who is too warm in a SNOO will exhibit the following signs:

  • Red ears
  • A sweaty neck
  • Agitated movements with their hands and legs
  • Crying

Be guided by the weather as well as the room temperature. If your baby responds well to the soothing motion of the SNOO they’re both comfortable and warm enough. 

How to Know if Your Baby is Feeling Cold in the SNOO

There are a number of signs to look out for when your baby is feeling cold in a SNOO. These include the following:

  • A cold chest, tummy, or back.
  • Your baby cries a lot during winter. 
  • Your baby’s lips have a slight blue tinge.

If your baby develops hypothermia, it becomes a medical emergency. This is when the body temperature drops below 35 degrees Fahrenheit. They exhibit signs of shivering, slower breathing, and dilated pupils. 

Differences Between the SNOO Sack vs Swaddle

When you compare the SNOO Sack with the Swaddle, you may be wondering what are the differences? They look almost identical but there are subtle differences. 

The SNOO Sack is specifically designed to be used when the baby is sleeping in the smart bassinet. They have extra wings with clips that are attached to the inside of the bassinet. The sack has breathable mesh keeping your little one cool while in the SNOO.

The Sleepea swaddle is designed to keep your baby comfortable and safe while napping outside of the SNOO bassinet. It looks identical to the SNOO sack without the extra wings. Inner “wings” are folded over your baby, swaddling their arms. The swaddle is then closed with a zip from the feet to the top.

The Sleepea also has breathable mesh for ventilation, preventing your baby from overheating. Both the SNOO Sack and Sleepea are available in three sizes – S, M and L. 

Watch this video as it demonstrates the differences nicely.

Can You Put Your Baby in SNOO Without the Swaddle?

You can put a baby in a SNOO without a swaddle. Your baby can be dressed in a cotton onesie such as the Gerber Short-Sleeve Onesies for nighttime sleeping. However, the founder of the SNOO Smart Sleeper maintains that the SNOO sleep sack prevents your baby from rolling over when sleeping. This gives your baby extra protection against smothering or even worse, sudden infant death syndrome (SIDS).

Baby Wearing a SNOO Sack

A SNOO Sack is made with 100% organic cotton. It’s also known as the 5-second swaddle! By attaching it to the bassinet with special clips, your baby is kept on their back when lying down. Inner armbands or wings keep your baby’s arms snug against their body, preventing them from flapping around. 

A double zipper allows you to unzip from the bottom or top for easy dressing or when doing a diaper change. If your baby detests being swaddled, unsnappable arm openings allow your baby to sleep with arms free. 

How Should the SNOO Sack Fit

The SNOO sleep sack should fit snugly without being too tight. Place the open sack down on the bassinet mattress before laying your baby on it. Your baby’s shoulders should be slightly above the top end of the sack.

Bring up the inner wings up over your baby’s chest, keeping their arms close to the sides of their body. Fasten the armbands. Bring up the bottom flap and seal it at the bottom of the armbands. Now, zip up the sack from the bottom, up to the top. 

Make sure the sack is not rubbing your little one’s neck. Check that your baby’s legs can move freely under the sack. At no times should their hips or legs be tightly constrained as this will hamper their normal hip development. 

Once your baby is safely swaddled, attach the SNOO sleep sack to the bassinet using the clips on the outer wings to either side of the crib. 

When to Size Up the SNOO Sack

The SNOO sleep sacks come in three sizes as follows:

  • Small (S): 5 – 12 lbs.
  • Medium (M): 12 – 18 lbs.
  • Large (L): 18 – 25 lbs. 

The best way to gauge when to move your baby up is to use the weight recommendations as a guideline. However, if you notice the sleep sack is too tight, go up a size. This is especially important when the legs and hips start to become too restricted and the armbands are too tight around the baby’s chest. 

When to Use the Medium SNOO Sack

The medium SNOO sack can be used when your baby reaches a weight of 12 lbs or has grown bigger in size, outgrowing the smaller sack. If your baby is too long for a size recommended for their small weight, you can use a medium SNOO sack to accommodate their extra length. However, always make sure the SNOO sack fits snugly around the chest so it doesn’t shift up to the shoulders while your baby is sleeping.

Can You Put a Blanket Over Your Baby in SNOO?

The manufacturer of the SNOO bassinet is quite adamant that no other objects should be placed inside the crib including blankets. If you’re worried about your baby getting cold, rather dress them in a onesie before placing them into a SNOO sack. 

If you’re not using a SNOO sleep sack, you can swaddle your baby in a light swaddling blanket before putting them to sleep in the bassinet. 

What Should a Baby Wear Under a SNOO Sack

Can Your Baby Wear Pajamas in SNOO?

Your baby can wear two-piece pajamas in a SNOO. Some parents will dress their babies in pajamas before putting them into a sleep sack, especially in the colder months.

Can Your Baby Wear a Onesie in SNOO?

Your baby can wear a onesie in SNOO. Try the Gerber Baby Long-Sleeve Onesies designed for both boys and girls. But, if you want to take advantage of the bassinet clip features to keep the baby securely on their back while sleeping, dressing them in the SNOO sleep sack is your answer. You can dress your baby in a onesie made with light materials before placing them into the SNOO sack.

During Summer

The SNOO sack is made with breathable material that’s soft and cozy. During the hot summer months, it’s not necessary to put anything under the SNOO sack as your baby will be more than comfortable. But, if you want to add an extra layer, use a lightweight onesie or wrap your baby in a muslin swaddling blanket before placing them into the sleep sack. 

During Winter

You can add additional layers under the SNOO sleep sack with warmer onesies or swaddling blankets. Keeping the baby’s room at an even temperature of 68 to 72 degrees Fahrenheit also means you don’t have to overdress your little one during the winter months. 

Baby Wearing a SNOO Swaddle

What to Wear Under a SNOO Swaddle

The SNOO swaddle or Sleepea is also made with 100% organic cotton. Breathable meshes on the legs and shoulders ensure your baby doesn’t overheat. In warmer months, you don’t need to put anything on your baby before wrapping them in a SNOO swaddle. 

But, if you feel your baby could do with another layer, use a light onesie or cotton or muslin swaddling blanket before wrapping them in the SNOO Sleepea.

What if the SNOO Swaddle is Not Warm Enough?

If the SNOO swaddle isn’t warm enough, add another layer with a onesie or swaddling blanket. Make sure your baby’s arms are snug against their body when using a swaddling blanket to ensure the Sleepea works optimally. 

You could also ensure the room temperature is set correctly to help keep your baby warm in a SNOO swaddle and avoid any direct air blowing onto them. 

What is Double Swaddling With the SNOO?

You can double swaddle your baby with a SNOO. But, always make sure your baby doesn’t overheat by using a lightweight swaddling blanket under a SNOO sack or Sleepea. Double swaddling can be used when your baby needs some comfort before being placed in the SNOO bassinet This can be done by laying the SNOO sack into the bassinet and attaching it to the side clips. Turn on the motion.

Wrap your newborn in a cotton or muslin swaddling blanket and hold them for a few minutes before placing them into the bassinet. Zip up the SNOO sack and your baby will be asleep before you know it!

Can Your Baby Wear a Hat in SNOO? 

Your newborn baby can wear a hat in SNOO as long as they don’t overheat and the indoor temperature is below 55 degrees Fahrenheit. I’ve written an article answering the question of whether newborn babies should wear hats, so read it if you want more information on this topic. 

Can Your Baby Wear Some Baby Monitor(s) With the SNOO?

Wearing Nanit Breathing Wear in the SNOO

The manufacturers of the Nanit breathing wear monitors mention that their Nanit products work with the SNOO. But, they do caution they can’t guarantee the Nanit signal alerts and insights will work the same because of the SNOO sounds and motions. 

Other Baby Monitors

Baby monitors are a must-have for parents who want to see what is happening when their baby is sleeping without having to go into the baby’s room every five minutes. Because the SNOO smart sleeper uses sounds and motion to help your baby sleep, some baby monitors may be too sensitive. This means unnecessary alert signals could be triggered. 

When looking for the best baby monitor for the SNOO bassinet look for wall-mounted units that won’t be affected by the crib’s rocking motions. You can also use floor stands to mount your baby monitor and this is a good option when using baby monitors with the SNOO.


There are so many things you should know before purchasing a SNOO including their sleep sacks and Sleepea swaddles. These clothing items keep your baby happy while sleeping in the SNOO bassinet or taking a nap outside the crib. By reading my article, you should be well-informed about how to dress your baby for a SNOO.

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