A newborn should sleep in a fitted one-piece sleepsuit or a wearable blanket (sleep sack) placed on a firm, flat mattress with nothing else in the crib. No loose blankets, no pillows, no stuffed animals. The safest setup is simple: a bare crib with a tight-fitting sheet and a baby dressed in one extra layer compared to what you’re comfortable wearing.
Wearable Blankets and Sleep Sacks
The American Academy of Pediatrics recommends wearable blankets over loose bedding. A sleep sack zips around your baby’s torso and leaves their arms free, keeping them warm without the suffocation risk that comes with a traditional blanket. Because newborns can’t pull fabric away from their face, anything loose in the crib is a hazard.
Sleep sacks come with a warmth rating called a TOG number. The right TOG depends on how warm the room is:
- Above 80°F: 0.2 TOG (very lightweight, almost like a single layer of cotton)
- 73–79°F: 0.5 TOG
- 68–73°F: 1.0 TOG
- 61–68°F: 2.5 TOG
- Below 60°F: 3.5 TOG
If you don’t have a sleep sack, dressing your baby in layers of fitted clothing works just as well. A onesie under a footed sleepsuit is a standard combination for a room in the 68–72°F range.
Swaddling: When It Works and When to Stop
Swaddling can help calm a newborn and reduce the startle reflex that wakes them. But there’s no evidence it reduces the risk of SIDS, and it comes with its own rules. A swaddled baby must always be placed on their back, never on their side or stomach.
The most important rule: stop swaddling as soon as your baby shows any signs of trying to roll over. A swaddled baby who ends up face-down can’t use their arms to reposition, which creates a suffocation risk. Some babies start attempting to roll as early as two months, though it more commonly happens between two and four months. After two months, it’s worth reassessing whether swaddling is still appropriate.
How you swaddle matters for hip health, too. The International Hip Dysplasia Institute recommends keeping the swaddle snug around the chest and arms but loose around the hips and legs. Your baby’s legs should be free to bend up and spread outward naturally. Wrapping the legs straight and tight increases the risk of hip dysplasia. Look for swaddle products that have a roomy pouch at the bottom rather than a tight wrap all the way down.
What to Keep Out of the Crib
The list of items that should not be in a newborn’s sleep space is longer than most parents expect. Pillows, quilts, comforters, stuffed animals, bumper pads, fur-like materials, and loose blankets all increase the risk of suffocation, entrapment, and SIDS. Even items marketed as sleep aids aren’t necessarily safe.
Weighted blankets, weighted swaddles, and weighted sleep sacks are not safe for infants. The CPSC, CDC, AAP, and NIH all agree on this point. A newborn’s rib cage is still flexible, and the pressure from weighted products can make it harder for them to breathe and for their heart to beat properly. There’s also evidence that weighted sleep products can lower a baby’s oxygen levels, which may harm their developing brain. If you see a weighted product marketed for infant sleep, skip it.
Hats should also come off once you’re home from the hospital. Indoor hat use offers little benefit for preventing heat loss and actually increases the risk of overheating.
The Right Room Temperature
A nursery between 68 and 72°F is comfortable for most babies. Anything above 72°F may be too warm. Overheating during sleep is a known risk factor for SIDS, so erring on the slightly cooler side and adding a layer of clothing is safer than cranking up the heat and hoping the baby isn’t too hot.
A practical guide from the NHS: dress your baby in one more layer than what you’re wearing and feel comfortable in. If you’re fine in a t-shirt and a sweater, your baby would be comfortable in a bodysuit, a sleepsuit, and a light cardigan or sleep sack. If you feel chilly, your baby probably does too. To check whether your baby is overheating, feel their chest or the back of their neck. Hands and feet tend to run cool on newborns and aren’t reliable indicators.
The Sleep Surface
Your newborn should sleep on a firm, flat mattress that fits snugly inside the crib, bassinet, or play yard with no gaps around the edges. The mattress should be covered with a single fitted sheet and nothing else. Crib mattresses in the U.S. must meet federal firmness standards set by the CPSC, so purchasing a new mattress from a reputable manufacturer is the simplest way to ensure it’s safe. Mattress toppers, memory foam pads, and soft surfaces are not appropriate for infant sleep.
A full-size crib, a bassinet, or a portable play yard with a firm mattress all meet the criteria. What matters is the surface itself: firm enough that it doesn’t conform to your baby’s face if they turn their head, and flat rather than inclined. Products that position a baby at an angle, like certain rockers and swings, are not designed for unsupervised sleep.