The safest way to keep your baby warm at night is to set the room temperature between 68°F and 72°F, dress them in one more layer than you’d wear yourself, and use a wearable blanket instead of loose bedding. Getting this balance right matters more than most parents realize, because overheating is a greater risk than being too cold and has been linked to sudden infant death syndrome (SIDS).
Set the Right Room Temperature
Keep your baby’s room between 68°F and 72°F (20°C to 22°C). This range is warm enough that your baby won’t need heavy layers but cool enough to avoid overheating. A simple room thermometer near the crib gives you a reliable reading, since your own perception of warmth can shift depending on what you’re wearing or how tired you are.
Where you place the crib also affects how warm your baby stays. Texas Children’s Hospital recommends keeping the crib at least two feet away from heating vents, windows, and wall lamps, and at least one foot from walls and furniture. A crib directly under a vent can create hot spots, while one near a drafty window can leave your baby too cold, even if the thermostat reads 70°F.
Use the One-Layer Rule
A good starting point: dress your baby in one more layer than you’d comfortably wear in the same room. If you’re fine in a t-shirt, your baby likely needs a onesie plus a light sleep sack. If you need a sweatshirt, your baby probably needs a long-sleeved onesie under a warmer sleep sack. This rule scales naturally with the seasons and keeps you from second-guessing every outfit.
For newborns, a cotton bodysuit or footed pajamas under a sleep sack covers most situations. Skip socks under footed pajamas (they can bunch up and come off), and avoid layering multiple blankets or quilts over your baby. The goal is even, consistent warmth without bulk.
Choose the Right Sleep Sack TOG Rating
Sleep sacks (also called wearable blankets) are rated by TOG, a measure of thermal resistance. Higher TOG means more warmth. Matching the TOG to your room temperature keeps your baby comfortable without overheating:
- 0.2 TOG: Best for warm rooms, 75°F to 81°F
- 1.0 TOG: Ideal for 68°F to 75°F, the standard comfort range
- 1.5 TOG: Works well for 64°F to 72°F
- 2.5 TOG: Suited for cooler rooms, 61°F to 68°F
- 3.5 TOG: Only for rooms below 61°F
Most homes in the recommended range will do well with a 1.0 TOG sleep sack. If your home runs cold in winter or you keep the thermostat low at night, a 2.5 TOG with a lighter base layer underneath is a safer bet than piling on extra clothing.
Why Loose Blankets Are Not Safe
Loose blankets, comforters, and quilts should not go in the crib. They can cover your baby’s face, creating a suffocation risk, or bunch around the body and cause overheating. Wearable blankets solve both problems. They stay in place, can’t ride up over your baby’s face, and come in sizes from newborn through toddlerhood.
For newborns who like the snugness of swaddling, swaddle-style sleep sacks wrap the arms securely. Once your baby starts showing signs of rolling (typically around 8 weeks, though it varies), switch to an arms-out wearable blanket so they can use their hands to push up and reposition if they roll onto their stomach. Toddler versions with foot openings let older children walk to the crib and move freely while still staying warm.
Skip the Hat Indoors
The American Academy of Pediatrics advises against putting hats on babies sleeping indoors, except during the first hours after birth or in a neonatal intensive care unit. A baby’s head is a major route for releasing excess heat. Covering it during sleep traps that heat and raises the risk of overheating, especially under blankets or in a warm room.
How to Check if Your Baby Is Too Warm or Too Cold
Cold hands and feet are normal in babies and don’t reliably tell you whether they’re warm enough. Instead, feel the skin on your baby’s chest, tummy, or back. It should feel comfortably warm, not hot or clammy and not cool.
Signs your baby is too cold include shivering, unusually slow breathing, and pale or cool skin on the torso. Signs of overheating are more visible: flushed or reddened skin, sweating (especially on the back of the neck or head), and general restlessness or discomfort. If your baby’s chest feels hot and damp, remove a layer or switch to a lower-TOG sleep sack.
Why Overheating Is the Bigger Risk
Parents tend to worry more about their baby being cold, but overheating poses the more serious danger. Heat stress and elevated body temperature are common findings in SIDS cases. Research published in Frontiers in Pediatrics found that thermal stress can disrupt a baby’s heart rate, breathing, and ability to wake up in response to danger, all of which are protective mechanisms during sleep. Profuse sweating has been documented at the scene of multiple SIDS cases, reinforcing the connection between excess heat and risk.
Overheating doesn’t appear to cause SIDS on its own. Instead, it acts as an additional stressor that weakens a baby’s built-in defenses. A baby who is too hot is less likely to rouse from sleep when breathing becomes compromised. This is why getting the temperature and layering right isn’t just about comfort; it’s a genuine safety measure.
A Quick Nighttime Checklist
- Room temperature: 68°F to 72°F
- Clothing: One layer more than you’d wear
- Sleep sack: TOG matched to room temperature
- Crib placement: Away from vents, windows, and direct heat sources
- No loose bedding: No blankets, quilts, or pillows in the crib
- No hat: Leave your baby’s head uncovered indoors
- Check warmth: Feel the chest or back, not the hands or feet