Infants should sleep in a crib, bassinet, or play yard with a firm, flat mattress and nothing else inside. For clothing, a fitted sleep sack or wearable blanket is the safest option to keep your baby warm without loose bedding. These basics apply from birth through the first year, though the specifics shift as your baby grows and hits new milestones.
Safe Sleep Surfaces
The three main options for where your baby sleeps are a full-size crib, a bassinet, and a portable play yard. All three are considered safe as long as the mattress is firm, flat, and fits snugly against the sides with no gaps. A mattress that passes the “press test” (push down on it and it springs right back) is firm enough. If you can fit more than two fingers between the mattress edge and the crib wall, the mattress is too small.
Bedside sleepers, which attach directly to your adult bed, are another option. These are regulated by the U.S. Consumer Product Safety Commission and must meet specific standards for how securely they attach, how high the barrier walls are, and how close the sleeper sits to the adult mattress. They give you easy access for nighttime feeding while keeping the baby on a separate, approved surface.
Whatever you choose, the sleep space should be completely bare. No blankets, pillows, bumper pads, stuffed animals, or positioning devices. Soft items in a baby’s sleep area increase the risk of suffocation, entrapment, and SIDS. The only things in the crib should be your baby and a fitted sheet.
Products That Are Banned or Unsafe
Inclined sleepers are now illegal to sell, manufacture, or import in the United States. Federal law defines an inclined sleeper as any product with a sleep surface angled more than ten degrees that’s designed for infants under one year. These products were linked to dozens of infant deaths before being pulled from the market.
Crib bumpers are also banned. This includes padded bumpers, vinyl bumper guards, and vertical slat covers. Non-padded mesh liners are the only exception, though many safety organizations recommend skipping those too and simply leaving the crib sides bare. Babies can press their faces against padded bumpers and suffocate, or get limbs tangled in loose fabric.
Weighted swaddles and weighted blankets are unsafe for infants. They place too much pressure on a baby’s chest and lungs. If you see these marketed for newborns, pass on them.
Swaddling in the Early Weeks
For newborns, swaddling with a thin blanket is a common way to help them feel secure and reduce the startle reflex that wakes them. Safe swaddling means wrapping snugly enough to stay in place but loose enough that you can slide two or three fingers between your baby’s chest and the fabric. The legs should be able to bend up and out freely, which orthopedic specialists call “hip-healthy swaddling.” Tight wrapping around the hips can contribute to hip problems.
A few firm rules apply: always place a swaddled baby on their back, use only a thin blanket, and never leave a loose swaddle in the crib. A blanket that comes unwrapped becomes exactly the kind of loose bedding that creates suffocation risk.
When to Stop Swaddling
You need to stop swaddling the moment your baby shows any signs of rolling over. This typically happens between 2 and 6 months, sometimes earlier. Signs to watch for include rolling during playtime, pushing up on their hands during tummy time, lifting their legs and flopping them to one side, or repeatedly breaking free from the swaddle. If a swaddled baby rolls onto their stomach, the wrapped arms prevent them from pushing up or repositioning, which creates a serious breathing hazard.
A decreased startle reflex is another signal. If your baby no longer flings their arms out when startled, the main benefit of swaddling has passed and it’s time to transition.
Sleep Sacks and Wearable Blankets
Once you move past swaddling, a sleep sack is the go-to solution for keeping your baby warm safely. Sleep sacks are wearable blankets that zip on over your baby’s pajamas, leaving their arms free while enclosing the torso and legs in a pouch of fabric. Unlike a loose blanket, they can’t ride up over your baby’s face. You can use sleep sacks for as long as you want, well into toddlerhood if your child tolerates them.
Sleep sacks come in different thicknesses measured by a TOG rating, which indicates how much warmth the fabric provides. Matching the right TOG to your room temperature prevents overheating, which is itself a risk factor for SIDS:
- 0.2 TOG: Best for warm rooms, 75°F to 81°F
- 1.0 TOG: Best for typical rooms, 68°F to 75°F
- 2.5 TOG: Best for cooler rooms, 61°F to 68°F
- 3.5 TOG: Best for cold rooms below 61°F
If you’re unsure which to pick, start with a 1.0 TOG for a room kept around 68 to 72 degrees, which is the temperature range research suggests is most comfortable for babies.
Getting the Room Temperature Right
Keeping the nursery between 68 and 72 degrees Fahrenheit is a good target. Anything above 72°F may be too warm. Overheating is a known risk factor for sleep-related infant deaths, so erring on the slightly cool side is safer than bundling up.
A quick way to check if your baby is the right temperature: feel the back of their neck or their chest. If the skin feels hot or sweaty, remove a layer. Cool hands and feet alone aren’t a reliable sign that a baby is too cold, since infant extremities naturally run cooler than the rest of their body. Dress your baby in one layer more than you’d wear comfortably in the same room, then use the appropriate TOG sleep sack on top.
What to Dress Your Baby In Under the Sleep Sack
A cotton onesie or footed pajamas underneath a sleep sack is usually enough. In warmer months or rooms, a short-sleeved bodysuit with a lightweight sleep sack works well. In winter, a long-sleeved onesie or footie pajamas paired with a thicker TOG sleep sack keeps your baby warm without any loose blankets. The goal is layering that you can adjust easily. If your baby wakes up sweaty, strip a layer. If their chest feels cool, add one.
Avoid hats for indoor sleep. Babies regulate heat through their heads, and a hat can cause them to overheat. Mittens and socks are fine if needed but shouldn’t be loose enough to come off and become a hazard in the crib.