Babies should always sleep on their backs, on a firm and flat surface, with nothing else in the crib. That single rule prevents more infant sleep deaths than any other intervention. Since the national Back to Sleep campaign launched in 1994, SIDS rates have dropped by roughly 50 percent. The details beyond that core rule matter too, and getting them right creates the safest possible sleep environment from day one.
Always on the Back, Every Time
Place your baby on their back for every sleep, whether it’s a full night or a quick nap. This applies from birth until your baby can consistently roll both ways on their own, which typically happens around 5 to 6 months. Stomach sleeping increases the risk of sudden infant death syndrome because young infants can rebreathe their own exhaled air or struggle to lift their heads to clear their airway.
Some parents worry that back sleeping will cause choking if the baby spits up. Healthy babies naturally swallow or cough up fluid on their own, and back sleeping does not increase choking risk. If your baby rolls onto their stomach during sleep after they’ve mastered rolling in both directions, you don’t need to reposition them. But always start them on their back.
The Right Sleep Surface
Your baby’s mattress should be firm, flat, and fit snugly inside a safety-approved crib or bassinet. “Firm” means the mattress doesn’t conform to your baby’s face or head when they’re lying on it. Crib mattresses sold in the U.S. must meet federal firmness testing standards (ASTM F2933), so buying a new, certified mattress is the simplest way to ensure compliance. Avoid used mattresses with unknown history, since they may have softened or degraded over time.
Cover the mattress with a single fitted sheet and nothing else. No blankets, no pillows, no stuffed animals, no bumper pads. Young babies cannot lift their heads to pull away from soft objects that press against their faces, making any loose item in the crib a suffocation hazard. The U.S. Consumer Product Safety Commission specifically warns against weighted blankets, weighted swaddles, and any inclined product angled more than 10 degrees. Rockers, gliders, swings, and bouncers are not safe sleep surfaces, even if your baby falls asleep in one.
Room Sharing Without Bed Sharing
Keep your baby’s crib or bassinet in your bedroom for at least the first six months. Room sharing makes nighttime feeding easier and lets you monitor your baby, and it’s associated with lower SIDS risk. Bed sharing is a different matter entirely. Adult mattresses, pillows, and bedding all create suffocation risks for infants, and a sleeping adult can inadvertently roll onto a small baby.
Room Temperature and Clothing
The ideal room temperature for a sleeping baby is 68 to 72°F (20 to 22°C). Overheating is a known risk factor for SIDS, so dress your baby in one layer more than you’d wear comfortably in the same room. A sleep sack or wearable blanket works well once your baby has outgrown swaddling.
To check whether your baby is too warm, touch the back of their neck. If it feels sweaty, they’re overdressed. You can also feel their chest or ears. Skip the hands and feet for temperature checks, since those always run cooler than the rest of the body. Flushed skin or unusual fussiness can also signal overheating.
When to Stop Swaddling
Swaddling can help calm a newborn’s startle reflex and promote sleep in the earliest weeks. But you need to stop swaddling as soon as your baby shows any signs of rolling over. For some babies, this happens as early as 8 weeks. For others, it’s closer to 4 to 6 months. The average window is 2 to 6 months.
Watch for these cues during awake time: pushing up on their hands during tummy time, lifting their legs and flopping them to the side, attempting to roll during play, or consistently breaking free from the swaddle wrap. A swaddled baby who rolls onto their stomach may not be able to roll back, which restricts breathing and creates serious risk. A loose swaddle on a mobile baby is also a suffocation hazard. Transition to a sleep sack with free arms at the first sign of rolling.
How Much Sleep Babies Need
Newborns under 4 months sleep a lot, but their patterns vary so widely that sleep medicine experts don’t set a specific recommendation for that age. Some newborns sleep 11 hours in a 24-hour period, others sleep 19. Both can be normal.
From 4 to 12 months, the American Academy of Sleep Medicine recommends 12 to 16 hours of total sleep per 24 hours, including naps. From 1 to 2 years, the target drops slightly to 11 to 14 hours. These are ranges, not rigid targets. If your baby falls a bit outside them but is growing well, feeding normally, and meeting developmental milestones, there’s usually no cause for concern.
What Normal Baby Sleep Looks Like
Newborn sleep can look alarming if you don’t know what to expect. About half of a newborn’s sleep is active (REM) sleep, during which they may twitch, jerk their arms or legs, make faces, and move their eyes under closed lids. Their breathing during active sleep is often irregular. It may pause for 5 to 10 seconds, then resume with a burst of rapid breaths at 50 to 60 per minute for 10 to 15 seconds before settling into a regular rhythm again. This pattern, called periodic breathing, is normal in young infants.
The other half of their sleep is quiet (non-REM) sleep, when twitching stops and the baby becomes progressively harder to wake. As babies mature over the first year, they spend a greater proportion of sleep in these deeper, quieter stages, and their sleep cycles lengthen and consolidate.
Pacifiers and Breastfeeding as Protective Factors
Offering a pacifier at sleep time, for both naps and nighttime, is associated with reduced SIDS risk. If you’re breastfeeding, wait until nursing is well established (typically around 3 to 4 weeks) before introducing one. If the pacifier falls out after your baby falls asleep, you don’t need to replace it. The recommendation applies through the first year, which covers the peak risk period for SIDS.
Breastfeeding itself is one of the strongest protective factors. A meta-analysis of 18 studies found that any amount of breastfeeding for any duration reduced SIDS risk by roughly 60 percent compared to no breastfeeding. Exclusive breastfeeding showed an even greater protective effect, with about a 73 percent reduction. The protection likely comes from multiple factors, including immune support and the way breastfed infants tend to rouse more easily from sleep.
Common Mistakes to Avoid
- Falling asleep while feeding in a chair or on a couch. Couches and armchairs are among the most dangerous places for an infant to sleep. If you feel drowsy during a feeding, move to your bed (cleared of pillows and blankets) rather than risk falling asleep on upholstered furniture.
- Letting the baby sleep in a car seat outside the car. Car seats are designed for travel safety, not sleep. The inclined position can cause a young baby’s head to fall forward, restricting their airway.
- Using products marketed as “sleep positioners.” Wedges, nests, and anti-roll devices have no safety benefit and introduce suffocation risk.
- Adding blankets when the room feels cold. Use a warmer sleep sack instead. Loose blankets should stay out of the crib entirely until at least 12 months.