Babies sleep in a crib, bassinet, play yard, or bedside sleeper placed on a firm, flat mattress with nothing but a fitted sheet. That’s the full list of safe options for the first year of life. What they wear to bed matters too: a onesie or pajamas under a sleep sack replaces the blankets and loose bedding that adults use but babies cannot safely have.
Safe Sleep Surfaces for the First Year
The American Academy of Pediatrics recommends a firm, flat, noninclined sleep surface for every sleep, including naps. In practice, this means one of four products:
- Full-size crib: The standard choice that lasts until your child transitions to a toddler bed, typically around age 2 or 3. The mattress should fit snugly with no gaps between it and the crib sides.
- Bassinet or cradle: Smaller and portable, designed for the first few months. Many parents keep one next to their bed for easier nighttime feeds.
- Play yard (pack ‘n play): A portable option with a thin, firm mattress. These work well for travel or as a second sleep space in a living area. Use only the mattress pad that came with it.
- Bedside sleeper: A rigid-framed sleep space that attaches directly to the side of an adult bed, letting you reach your baby without getting up. These must meet specific federal safety standards set by the Consumer Product Safety Commission, including requirements for how securely they attach and the height of their barriers.
Any surface with an incline greater than 10 degrees is unsafe for sleep. That rules out swings, bouncers, car seats, and inclined rockers as sleep spots, even if your baby dozes off in one. Sleep surfaces that meet federal safety requirements will say so on their packaging.
What Goes in the Crib (Almost Nothing)
The safest crib is a bare one. The only thing on the mattress should be a single fitted sheet. No pillows, no blankets, no bumper pads, no stuffed animals, no quilts, and no mattress toppers. Babies who sleep on soft or squishy surfaces, or with soft items nearby, face a higher risk of suffocation, entrapment, and SIDS.
Weighted blankets, weighted swaddles, and weighted sleepers are also off the list. The AAP specifically recommends against placing any weighted objects on or near a sleeping infant. Crib bumpers, even the mesh “breathable” kind, add unnecessary risk with no proven benefit.
This bare-crib rule applies to all four sleep surfaces. The CPSC sums it up simply: “Bare is best.”
Where to Put the Crib
For at least the first six months, your baby’s sleep space should be in your bedroom. Room sharing (not bed sharing) is protective. Placing the crib or bassinet close enough that your baby is within view and arm’s reach makes nighttime feeding and monitoring easier without the risks that come with sharing your mattress.
The AAP does not recommend bed sharing under any circumstances, even though many families choose it. The separate-surface-same-room setup is the closest match between convenience and safety that current evidence supports.
What Babies Wear to Sleep
Since loose blankets are out, babies stay warm through what they’re wearing. The general approach is a base layer (a onesie or footed pajamas) plus a wearable blanket, commonly called a sleep sack. Sleep sacks zip on and can’t ride up over a baby’s face the way a blanket can.
A good starting rule from the NHS: dress your baby in one more layer than what you’re comfortable wearing. If you’re fine in a t-shirt, your baby probably needs a onesie plus a light sleep sack. If you’re reaching for a sweater, your baby may need pajamas under a warmer sleep sack.
To check if your baby is the right temperature, feel their chest or the back of their neck. Warm skin means they’re comfortable. Hot or sweaty skin means remove a layer. Don’t worry about cool hands or feet, which are normal in young babies and not a reliable sign of being cold.
How TOG Ratings Work
Sleep sacks come with a TOG rating, which measures thermal resistance, or how much warmth the fabric holds in. Higher TOG means warmer. Matching the right TOG to your nursery temperature keeps your baby comfortable without overheating, which is itself a risk factor for SIDS.
- 0.2 TOG: For warm rooms, 75°F to 81°F. Essentially a single layer of lightweight fabric.
- 1.0 TOG: For typical room temperatures, 68°F to 75°F. The most commonly used weight year-round in climate-controlled homes.
- 2.5 TOG: For cooler rooms, 61°F to 68°F. Pair with pajamas underneath.
- 3.5 TOG: For rooms below 61°F. The warmest option, usually needed only in unheated spaces during winter.
The ideal nursery temperature is between 68°F and 72°F (20°C to 22°C). Keeping the room in this range with a 1.0 TOG sleep sack and a layer underneath covers most situations comfortably.
Swaddling and When to Stop
Newborns are often swaddled, wrapped snugly in a thin blanket or a purpose-made swaddle wrap with hook-and-loop closures. Swaddling helps calm the startle reflex that wakes young babies, and many newborns sleep longer and more soundly when swaddled. Arms should be positioned so the hips can move freely, and the swaddle should be snug around the chest but not tight enough to restrict breathing.
You need to stop swaddling as soon as your baby shows any signs of rolling over. For most babies, this happens between 8 and 16 weeks. Signs to watch for include: rolling to one side during playtime, pushing up on their hands during tummy time, lifting their legs and flopping them sideways, or repeatedly breaking out of the swaddle. A baby who rolls onto their stomach while swaddled can’t use their arms to reposition, which creates a suffocation risk.
The transition from swaddle to sleep sack can be rough for a few nights. Some families use transitional products with wings or partially enclosed arms to ease the shift. Once your baby is in a sleep sack, they’ll use it for the rest of their first year and often well into toddlerhood.
After-Market Mattresses and Add-Ons
If your baby sleeps in a play yard, use only the mattress pad that shipped with it. After-market play yard mattresses have been the subject of federal recalls. In January 2024, the CPSC issued a warning about a brand of play yard mattresses due to suffocation risk and violation of federal crib mattress regulations. A thicker or softer replacement mattress can create gaps at the edges or a surface that’s too soft, both of which are dangerous.
The same logic applies to crib mattresses. If you’re buying a replacement, it needs to meet current federal safety standards and fit the crib frame with no more than two finger-widths of space between the mattress edge and the crib side. Memory foam, pillow-top, and dual-comfort mattresses marketed for adults are not safe for infants.