Your newborn should sleep in a safety-approved crib, bassinet, or play yard with a firm, flat mattress and a fitted sheet. Nothing else belongs in the sleep space: no blankets, pillows, bumper pads, or stuffed animals. For clothing, a swaddle or a wearable sleep sack over a simple onesie is the safest choice for the first several months.
The Sleep Surface
A firm, flat mattress is non-negotiable. That means a crib, bassinet, or portable play yard that meets current safety standards, with only a snug fitted sheet covering the mattress. No inclined sleepers, no lounger pillows, no dock-a-tots. Inclined sleep products were linked to over 100 infant deaths before being pulled from the market, and anything that isn’t flat carries similar risks.
The mattress should feel harder than you’d expect. If it feels comfortable to you, it’s probably too soft for a newborn. A baby’s face can sink into a soft surface and block their airway, and they don’t yet have the strength or reflexes to reposition themselves. Every sleep, day or night, should happen on this same firm surface with your baby placed on their back.
Swaddling in the Early Weeks
For the first several weeks, a swaddle is often the best sleepwear choice. Wrapping your baby snugly in a thin blanket mimics the feeling of the womb and helps calm the startle reflex that wakes newborns. You can use a traditional receiving blanket or a zip-up swaddle product, whichever you find easier.
A few rules keep swaddling safe. You should be able to fit two or three fingers between the blanket and your baby’s chest. The swaddle should be snug around the arms and torso but loose around the hips and legs. The International Hip Dysplasia Institute recommends that a baby’s legs be free to bend up and out at the hips. Wrapping the legs straight and pressed together can increase the risk of hip dysplasia. Look for swaddle products with a roomy pouch at the bottom that lets your baby’s legs move naturally.
Stop swaddling as soon as your baby shows any signs of trying to roll over. Those signs include rocking their hips side to side, twisting their upper body, or reaching with both arms to one side. Some babies attempt rolling as early as six weeks. More conservative guidance suggests transitioning out of the swaddle by about eight weeks regardless, since development can be unpredictable. A swaddled baby who rolls onto their stomach cannot use their arms to push up or clear their airway.
Sleep Sacks After the Swaddle
Once your baby outgrows the swaddle, a wearable sleep sack is the go-to replacement. It’s essentially a blanket your baby wears, with arm holes and a zipper, so it can’t ride up over their face. Sleep sacks come in various warmth levels rated by a number called TOG, which measures thermal resistance. The higher the TOG, the warmer the garment.
Here’s a general guide based on nursery temperature:
- 0.2 TOG: for rooms between 75°F and 81°F (very warm)
- 1.0 TOG: for rooms between 68°F and 75°F (typical range)
- 2.5 TOG: for rooms between 61°F and 68°F (cool)
- 3.5 TOG: for rooms below 61°F (cold)
Most homes sit in the 68°F to 72°F range, which is the recommended nursery temperature. A 1.0 TOG sleep sack with a cotton onesie underneath covers this range well. In summer, a lightweight 0.2 TOG sack over a short-sleeved bodysuit, or even just a diaper, may be enough.
Choosing the Right Fabric
Cotton is the classic choice for newborn sleepwear: it’s soft, breathable, and widely available. Bamboo viscose has become a popular alternative because its fibers are naturally more porous, allowing better airflow. Bamboo is roughly 40 percent more absorbent than organic cotton and wicks moisture away from the skin faster, which helps if your baby tends to sleep hot. Either fabric works well. The more important thing is avoiding thick fleece or polyester in warm rooms, since these trap heat.
How to Tell If Your Baby Is Too Warm
Overheating during sleep is a known risk factor for SIDS, so getting the layers right matters. The best way to check is to touch the back of your baby’s neck or their chest. These areas give a more accurate read than hands or feet, which tend to run cool in newborns.
Signs your baby is too warm include flushed or red skin, sweating or damp hair, rapid breathing, and unusual fussiness or restlessness. Some babies overheat without visibly sweating, so skin temperature and color are more reliable signals. If your baby feels hot to the touch, remove a layer and check again in a few minutes. Keep the room between 68°F and 72°F, and skip hats for indoor sleep since babies release excess heat through their heads.
Products to Avoid
Weighted sleep sacks and weighted swaddles are not safe for infants. The Consumer Product Safety Commission, the CDC, the NIH, and the AAP all warn against them. A newborn’s rib cage is soft and flexible, and even modest pressure on the chest can make it harder to breathe and affect heart function. There is also evidence that weighted products can lower oxygen levels in ways that may harm a developing brain. Despite being marketed as soothing, these products carry real risk and should not be used for any sleep.
Loose blankets of any kind don’t belong in the crib, including swaddle blankets that have come unwrapped. If a blanket can cover your baby’s face, it’s a suffocation hazard. The same goes for pillows, stuffed animals, and crib bumpers, including the mesh “breathable” kind, which can still pose entanglement risks.
Putting It All Together
For the first couple of months, a typical setup looks like this: a firm crib or bassinet mattress with a fitted sheet, your baby on their back in a thin swaddle or arms-free swaddle suit, with a onesie or bodysuit underneath if the room is cool. After you stop swaddling, swap to a sleep sack at the appropriate TOG for your nursery temperature. Layer a bodysuit or pajamas underneath based on how warm or cool the room runs, and check your baby’s neck or chest periodically to make sure they feel comfortably warm but not hot.