Sleep Sacks

Sleep Sacks

What is a sleep sack?

According to the safe sleep guidelines of the American Academy of Pediatrics, we want to avoid using any loose blankets in the crib for the first 12 months of life, as they can pose a suffocation risk. Enter the sleep sack: a way to keep your baby warm and safe at the same time. A sleep sack is a wearable blanket that zips around your baby’s body and stays safely secured below your baby’s neck all night. With a sleep sack, you can rest assured knowing that your baby is warm and safe at the same time.


What’s the difference between a swaddle and a sleep sack?

A swaddle is designed for newborns, with the intention of keeping your baby’s arms tucked in. The sleep sack is designed to be worn with the arms out, so your baby can roll over safely once she has increased mobility. In short, swaddles are great for newborns and sleep sacks are the next step.


When can babies start wearing sleep sacks?

Technically you can put your baby in a sleep sack from day one, but newborns often sleep better when they’re swaddled. A sleep sack is the next step once your baby starts rolling over and is ready to move on from the swaddle. Sleep sacks are going to be your baby’s best friend from about 4 months till she’s old enough for a bed. They go up in size till 36 months and although it’s considered safe to give your baby a loose blanket at 12 months, I recommend keeping the sleep sack for much longer than that! 

Sleep sacks are a great sleep association, don’t fall off in middle of the night and can deter your baby from climbing out her crib once she hits the toddler stage.


Why use a sleep sack?


1. A sleep sack is a great way to keep your baby warm, while staying safe. Once your baby shows signs of rolling, it’s time to transition out of the swaddle and graduate to a sleep sack. 


2. Sleep sacks can be a great sleep cue: after a few nights, your baby will start to associate the sleep sack with sleep, and the very act of putting it on will begin the process of mentally prepping your baby for bed. 


3. Once your baby grows into the toddler stage, sleep sacks can be a great deterrent towards climbing out of the crib! It’s hard to scale a crib wall while wearing a blanket, yet your baby will still have a wide range of movement to able to roam the crib freely.


4. While not foolproof, a sleep sack can be helpful if your baby gets his feet stuck between the slats of the cribs. The additional fabric surrounding his feet makes it that much harder to get stuck 


baby on sleep sack

TOG and Sleep Sacks

TOG: Thermal Overall Grade. In plain English, the TOG level determines the thermal insulation: how much of your baby’s body heat the fabric retains, i.e., how heavy or light the sleep sack is. (TOG can also apply to swaddles and even pajamas!) TOG levels were created as a concrete way to measure how warm or cool a blanket/pajamas/swaddle are, in an effort to reduce the risk of SIDS from overheating. 


Why Does TOG Matter?

Babies aren’t great a regulating their own body temperature, especially preemies. If a baby is dressed in sleep sack that is too warm for the room, it’s more likely that he will overheat. Since overheating is a risk factor for SIDS, it’s something to be mindful of at all times. 

The higher the TOG level, the warmer it will keep your baby. It can helpful to use the following TOG levels to each corresponding temperature: 

.25 TOG
79+ degrees F
Very warm room with limited ventilation, summer weather with poor air conditioner, heat wave
Just a diaper
.5 TOG
73-78 degrees F
Warm room
Short sleeve onesie
Ideal room temperature for babies
2.5 TOG
Cold room, winter room without adequate heating
Warm pajamas

It’s imperative to use your judgement here. If you have the heat turned on high in the winter, you may not want to use a winter sleep sack with a higher TOG rating. Conversely, if the ac is blasting in the summer and your baby’s room is cold, a sleep sack with a low TOG rating may not be enough to keep her warm. Always judge by the temperature in your baby’s room, not outside. 

A 1.0 TOG is usually a safe bet, because you can always add or remove layers underneath the sleep sack (onesie, pajamas) if baby seems to warm or cold. Dressing your baby in a sleep sack with 1.0 TOG is like giving your baby 1 blanket. Every level upwards is like adding another layer, and every level downwards is like giving a thinner, lighter blanket. 

Bear in mind that it’s always safer for your baby to be slightly cool rather than slightly warm when sleeping. 


How to Know If Your Baby Is Too Warm or Cold


  • Feel your baby’s back, chest or back of her neck. Feeling toes or hands are not a reliable measure of body temperature because there is less blood flow to extremities, so they will always be slightly cooler than the rest of the body. 
  • Flushed cheeks, sweating, damp hair or listlessness can be signs of overheating 
  • Blue nose, fingers or toes, lethargy or decreased appetite can be signs that your baby is too cold. 

The rule of thumb when it comes to baby sleep is to dress your baby in no more than one extra layer than you are currently wearing, including the sleep sack. So if you are comfortable in your baby’s nursery in one layer, than give your baby one layer of pajamas, plus a sleep sack with an appropriate TOG. 

TOG can be a helpful tool to determine the right sleep sack for your baby, especially as the temperatures change along with the seasons. Remember that sleep sacks go up to size 36 months, so there’s no rush to move to a standard blanket at 12 months. You’ll thank me when that sleep sack stops your toddler from climbing out of her crib!  



Will starting solids help your baby sleep for a longer stretch at night?

You might have heard parents swear “as soon as we started solids she started sleeping 8 hours!” causing you to wonder if you should be feeding your baby real food too. What wouldn’t we do to gain a few more minutes of sleep at night?

Sadly, it doesn’t help. There is very little evidence that suggests a positive correlation between solids and longer stretches of sleep, and there is some evidence that suggests starting solids too early can disrupt sleep (just when you thought things couldn’t get any worse!)


3 secrets to get your baby
sleeping through the night!