What Should Baby Wear Under Sleep Sack?

Wondering what does baby wear under sleep sack?

Most parents want to ensure they have dressed their newborn baby for sleep appropriately, but what should baby wear under sleep sack?

As blankets aren’t recommend for small babies, when babies are sleeping, they usually wear a sleep sack, also known as a wearable blanket, or a swaddle.

The purpose of using a sleep sack is to provide warmth and comfort to babies during sleep safely.

But you also want to ensure they are not dressed too warmly that they overheat.

So, let look at what do babies wear under sleep sack!

And if you love this guide to what should babies wear under a sleep sack, then make sure to check out these guides on how to keep a baby warm at nightnewborn baby sleep tips, and should babies wear socks to bed. Or even our guide on what to wear under SNOO sack.

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Choosing A Sleep Sack

Sleep sacks are a recommended option over blankets to keep your baby warm at night as babies can not pull a blanket over their face this way. You can read more here on when can babies sleep with a blanket.

Yet, when choosing a sleep sack / wearable blanket there is a lot to take into consideration such as the baby’s age, size and weight and the temperature and climate. 

But first…

What Should A Baby Wear Under A Sleep Sack?

Unfortunately, there is no simple answer to this as once again there is a lot to consider, especially temperature.

To put it simply in warmer temperatures a baby will need less warmth and insulation than in colder temperatures.

It is important to remember that babies struggle to regulate their own body temperature and therefore wearing the correct materials and amount of layers is key to safe sleep. 

A General Guide

Obviously every baby is different, but there are generic guides available to give you an idea as to what your baby should be sleeping in in different room temperatures. 

  • Over 78 degrees Fahrenheit – If your baby is sleeping in a room that is more than 78 degrees Fahrenheit then there is no need for a sleep sack as this could cause them to overheat.

Instead babies should sleep in a baby vest as this should help to keep them the right temperature. 

  • 75 to 77 degrees Fahrenheit – If the room that your baby is sleeping in is anywhere between 75 and 77 degrees Fahrenheit then it is a good idea for them to still sleep in a vest but this time for them also to have a sleep sack.

In these instances the sleep sack should only be 0.5 tog. This is generally the lowest tog rating that you will find when it comes to sleep sacks, and it should stop your little one from overheating. 

  • 71 to 74 degrees Fahrenheit- If the room is between 71 and 74 degrees Fahrenheit then your baby should once again have a 0.5 tog sleep sack. 

However, this time it should be paired with a baby grow/sleep suit instead of a vest. This is because a sleep suit will help to keep your little one slightly warmer than a vest would. 

  • 69 to 70 degrees Fahrenheit – In these sorts of temperatures a baby should have a slightly thicker sleep sack so a 1.0 tog sleep sack is advised as this is slightly warmer than a 0.5 tog but still not too warm.

The sleep sack should also be paired with a baby vest and sleep suit. So in this instance your baby will in essence have three layers. 

  • 64 to 68 degrees Fahrenheit – In these temperatures a baby should sleep in very similar condition to the above (69 to 70 degrees Fahrenheit) however the only difference is that whereas in all higher temperatures the baby should sleep in a short-sleeved vest the vest should now be long sleeved.

So, in this circumstance the baby should have a 1.0 tog sleep sack, a sleep suit and a long sleeved vest. 

  • Under 63 degrees Fahrenheit – In temperatures under 63 degrees Fahrenheit the baby should still wear a long sleeved vest and a sleep suit, but they should now wear a 2.0 sleep sack and potentially some socks.

Some parents choose to not use socks as they see this as a suffocation hazard as the baby can take their socks off in the night, and they could potentially end up on the baby’s face, so this is up to you. 

Our Top Pick
Burt's Bees Wearable Baby Blanket
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Made with 100% organic cotton, this wearable baby blanket is sure to keep your baby warm and cozy as they sleep. It has a Zipper that opens from the bottom easy diaper access, is machine washable, and is carefully sized for baby to move around freely and safely. Burt's Bees wearable baby blankets come in a wide range of patterns and TOG to suit your baby's needs.


10/02/2022 11:04 am GMT

Are There Any Other Risks To Be Aware Of?

It is advised that babies do not sleep in hats or mittens as these do not aid safe sleep, instead they can cause suffocation.

Babies’ cribs or Moses baskets should always have nothing else in them.

For instance, they should never have loose blankets, soft toys or anything else in them to accompany the baby as once again this can lead to unsafe sleep and can even play a role in increasing your baby’s risk of SIDS (sudden infant death syndrome). 

How Many Sleep Sacks Should I Buy?

It is a good idea to buy a few sleep sacks before your baby is born as they will probably need them in a couple of different tog ratings, and they will also need to be washed, so it’s always good to have a spare or two. 

Final Thoughts on What Do Babies Wear Under Sleep Sack

As we’ve discussed sleep sacks are a safer alternative to blankets for babies. They come in different tog ratings so what you dress your baby under their sleep sack will depend on the temperature in your baby’s room and the tog rating of your sleep sack.

And if you’re looking for more great sleeping guides, then check out these sleeping guides on baby items starting with a to z checklist, should babies wear socks to bed, and when do babies stop wearing onesies.

what does baby wear under sleep sack