Dressing your baby in a fleece bear hooded onesie on chilly days is cute. But we can’t say the same if you let them go to bed like that. We've seen some parents wrap their babies in many layers of clothes and blankets, worried they might get cold during the night.
Here’s the kicker: tucking your baby in many layers of sleepwear and bedding in winter can do more harm than good. Using loose bedding goes against the safe sleep guidelines.
This is when a winter sleep sack comes in, bringing much-needed warmth without weighing them down. Time to say goodbye to dangerously loose blankets! Below is a detailed guide on how to use those sacks properly.
The Golden Rule of Winter: Safe Warmth, Say “No” to Blankets
The Risks of Layering Multiple Blankets
According to the National Institutes of Health, over bundling may cause infants to overheat, increasing their risk for SIDS. Many layers of blankets can weigh your little one down, making it hard to breathe normally. It also obstructs airflow and heat circulation, leading to overheating. That’s why a lightweight sleep sack is much safer than a blanket.
The Sleep Sack as the Perfect “Wearable” Blanket
A sleep sack blends the warmth of a blanket with the snugness of a onesie. A single winter sleep sack can replace many layers of blankets seamlessly.
It wraps around your baby’s body snugly while preventing them from kicking the sack off—something they can do easily with a blanket. This design keeps your little one cozy and safe consistently during chilly nights.
The Key for Winter: High TOG Ratings
Focusing on TOG 2.5 and 3.5
- 2.5 TOG: This rating is the most popular choice for winter sleep sacks, suitable for winters in most US states.
- 3.5 TOG: If you live in Northern states, where the temperature can drop below 61°F, this is the way to go.
How to Know When to Use a High TOG?
The best indicator is the room temperature. If you don’t have a heater and notice the temperature dips below 61°F, it’s time to switch to a sleep sack with a 2.5 TOG. Regulating the temperature properly is crucial to keep your baby warm.
What if your baby sleeps in a heated room? We hear this question all the time. Again, rely on the current room temperature to adjust accordingly.
For example, a 2.5 TOG sleep sack is a great choice even in a harsh Alaska winter, as long as the room temperature is between 61 to 68°F.
Ideal Fabrics for a Winter Sleep Sack
Multi-Layered Bamboo Fabric
Our unique quilting process layers thin bamboo fabric, which creates cozy little air pockets. This design effectively traps heat to keep your baby warm while still letting their skin breathe, so they stay perfectly comfortable.
For cozy and sweat-free winter nights, SwaddleAn made all sleep sacks with bamboo. They're all rated with a 2.5 TOG, the most common choice, to ensure your baby stays perfectly warm on cold nights.
Merino Wool: The Natural “Thermostat”
Merino wool is a premium choice known for its incredible warmth, even when damp. It also excels at regulating temperature, keeping your little one comfortable all night.
Fleece: Warm But Use with Caution
Fleece sleep sacks is incredibly warm, but it’s not the most breathable material. For this fabric, remember to use inner layers of a natural material to prevent your baby from getting sweaty.
This reminds us of a time when the Utah winter temperature plummeted to 28°F. We tried to bundle our baby up in the thickest fleece sleep sack we could find. Ten minutes later, his cheeks were as red as tomatoes.
We were panicking, thinking he had a fever. But it turned out we had just over-bundled him, as the temperature in the heated room was 62°F. We never want this to happen to your little ones.
A Guide to Dressing Your Baby in a Winter Sleep Sack
Deciding what to wear under the sleep sack is as important as choosing the right TOG rating. Here’s a quick guide to help you out:
| Room Temperature | Sleep Sack TOG Rating | What to Wear Inside |
| 64 to 68°F | 2.5 TOG | A diaper and a pair of long-sleeved pajamas |
| 61 to 63°F | 2.5 TOG | A diaper, a long-sleeved bodysuit, and a pair of pajamas |
| Below 61°F | 3.5 TOG | A diaper, a long-sleeved bodysuit, and a pair of footed pajamas |
Important Note: NEVER wear a hat for your baby when sleeping inside. Leave their head uncovered to dissipate heat and prevent overheating.
Dress Wise, Sleep Well!
A safe and cozy winter sleep starts with a winter sleep sack with an appropriate TOG rating. Your little one can stay warm and safe without the need for thick, dangerous blankets. Don’t let the cold winter interrupt your baby's sleep. Explore our winter bamboo sleep sack collections to find safe and gentle warmth for your baby!
Related Blog Post
The Best Summer Sleep Sacks for Baby Comfy Sleep
References
- NIH Alerts Caregivers to Increase in SIDS Risk During Cold Weather: https://www.nichd.nih.gov/newsroom/releases/110210-SIDS-risk-winter-alert