The simplest rule for layering a baby at bedtime: dress them in one more layer than you’d wear to sleep comfortably in the same room. That single guideline, recommended by the American Academy of Pediatrics, covers most situations. But the details matter, because babies can’t regulate their own body temperature the way adults can, and getting it wrong in either direction affects sleep quality and safety.
Start With the Room Temperature
Your layering choices depend entirely on how warm or cool the room is, so a room thermometer is the most useful tool you can buy. The Lullaby Trust recommends keeping a baby’s room between 16 and 20°C (roughly 61 to 68°F). That range feels slightly cool to most adults, which is the point. Babies generate heat efficiently but shed it poorly, so a room that feels neutral to you may already be warm for them.
If you don’t have a thermometer, pay attention to your own comfort. If you’re comfortable in a t-shirt, the room is likely above 20°C and your baby needs very little clothing. If you’d want a sweatshirt, the room is cooler and your baby will need more coverage.
What to Use Instead of Blankets
Loose blankets, quilts, comforters, and any soft bedding should stay out of the crib entirely. The AAP is clear on this: these items increase the risk of suffocation, entrapment, and head covering. Weighted blankets, weighted swaddles, and weighted sleepers are also specifically advised against.
A wearable blanket (sleep sack) is the safest alternative. It keeps your baby warm without any loose fabric that could shift over their face. Sleep sacks come in different thicknesses measured by a rating called TOG, which stands for Thermal Overall Grade. The higher the TOG number, the warmer the garment. Matching the TOG to your room temperature is the key to getting layers right.
TOG Ratings by Room Temperature
TOG ratings take the guesswork out of layering. Here’s how they map to room temperature:
- 0.2 TOG: Very lightweight, for rooms between 24 and 27°C (75 to 81°F)
- 1.0 TOG: Light, for rooms between 20 and 24°C (68 to 75°F)
- 1.5 TOG: Medium, for rooms between 18 and 22°C (64 to 72°F)
- 2.5 TOG: Warm, for rooms between 16 and 20°C (61 to 68°F)
- 3.5 TOG: Heavy, for rooms below 16°C (61°F)
These ranges overlap because what you dress your baby in underneath the sleep sack also contributes warmth. A 1.0 TOG sack with a long-sleeve onesie underneath will be warmer than the same sack over a short-sleeve bodysuit. That’s where the layering comes in.
Layering Combinations for Each Temperature Range
No single chart works perfectly for every baby and every product, because fabrics vary in thickness and insulation. But these combinations serve as a reliable starting framework.
In a cool room (16 to 20°C / 61 to 68°F), a long-sleeve bodysuit or footed pajama paired with a 2.5 TOG sleep sack works well. If your baby still feels cold, add a layer of clothing underneath rather than piling blankets on top. You might put a short-sleeve bodysuit under the footed pajama, then add the sleep sack.
In a comfortable room (20 to 24°C / 68 to 75°F), a short-sleeve or long-sleeve bodysuit with a 1.0 TOG sleep sack is typically enough. Many parents find this is the sweet spot for most of the year in climate-controlled homes.
In a warm room (above 24°C / 75°F), scale back significantly. A short-sleeve bodysuit with a 0.2 TOG sleep sack, or even just a bodysuit or diaper alone, is fine. In genuinely hot weather, a baby can sleep in just a diaper. There’s no minimum number of layers required.
In a cold room (below 16°C / 61°F), use a 3.5 TOG sleep sack over a footed pajama with a bodysuit underneath. This is the heaviest layering you should need. If your baby’s room regularly drops below 16°C, adjusting the heating is safer than adding more and more layers.
Fabric Choices That Help
The material matters almost as much as the number of layers. Cotton is breathable and widely available, making it a solid default for most temperatures. Its main drawback is that it holds moisture against the skin rather than pulling it away, so in hot weather it can feel clammy.
Bamboo viscose is lighter and actively wicks moisture, making it a better choice for warm nights. Most bamboo sleep sacks fall around 0.5 TOG, which keeps them from trapping excess heat. For everyday use in a temperature-controlled room, either cotton or bamboo works well. The priority is choosing fabrics that breathe rather than synthetic materials that trap heat.
How to Tell if Your Baby Is Too Warm
The best way to check is to feel your baby’s chest or the back of their neck. These areas reflect core body temperature more accurately than hands or feet, which tend to run cool in babies and aren’t a reliable gauge. A comfortable baby’s chest should feel warm but dry.
Signs your baby is overheating include:
- Skin that feels hot to the touch, especially on the chest
- Flushed or red skin
- Sweating or damp hair (though babies can overheat without visibly sweating)
- Unusual fussiness or restlessness
- Seeming unusually sluggish or limp
If you notice any of these, remove a layer and check again in 10 to 15 minutes. It’s better to err slightly on the cooler side. A baby who is a little cool will wake up and fuss, which is self-correcting. A baby who overheats may not signal as clearly.
Skip the Hat Indoors
Hats are a common instinct, especially for newborns, but the AAP advises against putting hats on babies for indoor sleep. After the first few hours of life, a hat can trap too much heat. Babies lose excess warmth through their heads, and covering that escape route is one of the easier ways to accidentally cause overheating. Save hats for outdoor trips in cold weather.
Swaddling and When to Transition
For newborns who aren’t yet rolling, a lightweight swaddle can replace a sleep sack. Look for swaddles that don’t trap heat, particularly breathable fabrics like bamboo viscose or thin cotton muslin. A swaddled baby in a warm room may not need any other clothing besides a diaper underneath.
Once your baby starts showing signs of rolling (typically around 2 to 4 months), transition to a sleep sack with arms free. The same TOG and layering principles apply. The only change is the style of the outer layer, not the overall approach to temperature management.
Putting It All Together
The layering process comes down to three steps. First, check the room temperature. Second, choose a sleep sack with the right TOG for that temperature. Third, add clothing underneath, keeping to one more layer than you’d wear yourself. Then verify by touching your baby’s chest about 10 minutes after putting them down. Over a few nights, you’ll develop a feel for what your baby needs in your specific home, and it becomes second nature.