Babies sleep best — and most safely — when they’re comfortably warm but never hot. A good rule: dress your baby in about one more light layer than you’d be comfortable in, use a wearable blanket instead of loose bedding, and keep hats off indoors. Overheating is a known risk factor for SIDS, so when in doubt, go lighter.
Key takeaways
- A comfortable room for most families is roughly 68–72°F (20–22°C).
- Check the back of the neck or chest, not hands and feet, to judge temperature.
- Use a sleep sack matched to the room temperature (TOG rating) instead of blankets.
- No hats, hoods or weighted products for sleep indoors.
- Sweating, damp hair, flushed cheeks or rapid breathing mean your baby is too warm.
What is a TOG rating?
TOG (thermal overall grade) measures how warm a fabric is. Sleep sacks are usually sold at about 0.5, 1.0, 1.5–2.5 TOG. Higher numbers are warmer. It’s a quick way to match the sleep sack to your nursery.
What to wear at each room temperature
| Room temperature | Sleep sack | Underneath |
|---|---|---|
| Above 75°F (24°C) | None or 0.2–0.5 TOG | Short-sleeve bodysuit or just a diaper |
| 72–75°F (22–24°C) | 0.5 TOG | Short-sleeve bodysuit |
| 68–72°F (20–22°C) | 1.0 TOG | Long-sleeve bodysuit or light pajamas |
| 64–68°F (18–20°C) | 1.5–2.5 TOG | Long-sleeve pajamas |
| Below 64°F (18°C) | 2.5 TOG | Pajamas plus a bodysuit |
These are starting points, not rules — every baby runs a little warmer or cooler. Always check your baby and adjust.
How to tell if your baby is too hot or too cold
- Too hot: sweaty neck or back, damp hair, flushed red cheeks, heat rash, rapid breathing, restlessness.
- Too cold: cool chest or back of neck (cool hands and feet are normal), fussiness, waking more often.
Babies regulate heat through their heads and faces, which is why hats indoors can make overheating more likely.
Why no blankets?
Loose blankets, quilts and comforters can cover a baby’s face. Wearable blankets give the same warmth without anything loose in the crib. Our safe sleep checklist explains the rest of the “empty crib” rule, and our swaddling guide covers the newborn weeks.
Practical tips
- Room thermometer: many monitors show room temperature, which takes the guesswork out of choosing layers.
- Fans and air conditioning: fine — just don’t point a fan directly at your baby.
- Heaters: keep space heaters well away from the crib, and never use an electric blanket for a baby.
- Illness: a baby with a fever needs fewer layers, not more. See our fever guide.
- Car seats: never put a sleeping bag or bulky coat under harness straps.
- your baby under 3 months has a rectal temperature of 100.4°F (38°C) or higher;
- your baby is unusually floppy, hard to wake, or breathing fast;
- you see a rash with fever, or your baby refuses feeds.
Frequently asked questions
Should my baby wear socks to bed?
Footed pajamas usually do the job. Cool feet are normal and don’t mean your baby is cold.
Is a 2.5 TOG sleep sack safe?
Yes, in a cool room. Just check your baby isn’t sweating, and switch to a lighter TOG if the room warms up.
What about weighted sleep sacks?
The AAP advises against weighted sleep sacks, swaddles and blankets for infants.
