Why Babies Should Sleep on Their Backs, Not Their Sides

It's 3 a.m. You've fed, burped and rocked your baby for the third time tonight. They finally drift off in your arms, and the moment you lay them down on their back, their eyes pop open. This scenario will be familiar to many tired parents of newborn and young infants. Suddenly, turning them onto their side, or letting them sleep on their tummy, looks very tempting. Resist it. Back sleeping is the safest sleep position for babies, for every nap and every night, throughout the first year.[1] As back sleeping became the norm in the United States, the rate of sudden infant death syndrome (SIDS) fell by 53% between 1992 and 2001.[2]

Position is only part of the picture. Your baby also needs a firm, flat, non-inclined sleep surface with a fitted sheet, and no pillows, loose blankets, positioners or other soft objects.[1]

This guide explains why back is best, why side sleeping isn't a safe alternative, what to do as your baby starts to roll, and how to handle spit-up and a baby who wakes the moment you lay them down. It follows US guidance from the American Academy of Pediatrics (AAP), the National Institutes of Health (NIH) and the Centers for Disease Control and Prevention (CDC). If you live elsewhere, check your local health authority, and ask your pediatrician if you're unsure.

Key Takeaways

• Start every sleep on the back, every nap and every night, whoever is caring for your baby, until their first birthday.[1]
• Side sleeping is not a safe in-between. It's unstable, and babies placed on their side roll onto their stomach more easily.[2][3]
• Even one nap in an unsafe position matters. Side and stomach positions are unsafe for all babies, and a single nap in either greatly increases SIDS risk.[3]
• Let rolling, not age, guide your next step. Stop swaddling at the first signs of rolling attempts. Only once your baby can roll both ways on their own can you leave them in the position they roll into.[3][4]
• The sleep space matters as much as the position. Firm, flat surface, fitted sheet, nothing else.[1]

Why Is Back Sleeping Recommended for Babies?

Back sleeping is crucial because stomach and side sleeping are consistently linked to a higher risk of SIDS.[2] SIDS is the sudden death of a baby under 1 year old that remains unexplained after a full investigation. It is one type of sudden unexpected infant death (SUID), a broader category that also includes accidental suffocation.[2][5]

The clearest real-world signal on the importance of back sleeping for infant safety came after pediatricians’ official guidelines changed. In the US, the share of babies placed on their stomachs to sleep dropped from 70% in 1992 to about 11% in 2002.[6] Over roughly the same period, the SIDS rate fell from 120 to 56 deaths per 100,000 live births, a drop of 53%.[2]

Research reviews reinforce this data. A 2024 review of earlier meta-analyses found that back sleeping was associated with about half the odds of SIDS compared with other positions.[7] Because these reviews pool observational studies, this strengthened the existing body of evidence that back sleeping is the safest position to put babies down in.

Sleep position also affects arousal, making it easier for babies to wake in response to a problem during sleep. Studies show babies are less likely to arouse when sleeping on their stomachs.[2] So if your baby seems to sleep more deeply on their tummy, that isn't a sign the position is safer. Instead, it might suggest your baby will have a harder time waking and repositioning if they end up sleeping in a way that blocks their breathing. 

Why Is Side Sleeping Not Recommended for Babies?

Side sleeping can look like a sensible compromise: your baby isn’t face down, and it seems as if spit-up will be less likely to enter the airway and cause your baby to choke. Side sleeping is still unsafe, for three reasons.

The position is unstable. A baby placed on their side can easily tip forward. The chance of rolling onto the stomach is significantly greater from the side than from the back.[2][3]

The risk is comparable to stomach sleeping. In one US study cited by the AAP, the SIDS risk linked to side sleeping was similar to the risk linked to stomach sleeping.[2]

Propping adds new hazards. Rolled towels, wedges, and positioners used to hold a baby on their side bring their own suffocation risk.[1][8]

The AAP is clear that placing your baby on their back is the only safe sleep position.[1][6]

If your baby has been sleeping on their side, try not to panic. SIDS is rare, and the most important step is the next one: place your baby on their back for every sleep, starting tonight.

When Can Babies Sleep on Their Side? Let Rolling Be Your Guide

Never place your baby on their side to sleep. Once your baby can roll from back to tummy and from tummy to back on their own, you can leave them in whatever position they roll into, including their side. Even when your baby is rolling both ways, it is important to continue placing them to sleep on the back until their first birthday.[3]

What changes along the way is how you respond, and that depends on what your baby can actually do, not on their age. Use this table to match your next step to your baby's rolling stage.[3]

If You Find Your Baby on Their Side or Stomach

It's common once babies start moving, and it doesn't mean you did something wrong. Use the table above to decide whether to turn your baby back over. Never use rolled towels, pillows or restraints to keep your baby in place, as anything besides a sleep sack is considered unsafe.[3][8] If your baby isn't breathing normally or isn't responsive, call 911 or your local emergency number.[9]

Can a Swaddle or Sleep Sack Keep My Baby on Their Back?

No. Neither can hold a baby in position, and neither should be used to try. Swaddling may make it harder for a baby to wake, which is especially dangerous if they end up on their stomach, and there's no evidence it lowers SIDS risk.[1][4] A correctly sized sleep sack that lets your baby move freely can replace loose blankets, but avoid weighted sleep products and wearables that wrap or compress the body like a swaddle once rolling starts.[1][4] For more on making the switch, see How to Transition from Swaddle to Sleep Sack: Timing, Tips, and What to Expect.

Back Sleeping Works Best in a Safe Sleep Space

Position and sleep space work together. An easy way to remember the basics is the ABCs of safe sleep, taught by many US health organizations: the safest way for your baby to sleep is Alone, on their Back, in a Crib (or bassinet).[10] Use a firm, flat mattress with a fitted sheet and nothing else in the sleep space. Keep the crib or bassinet in your room for at least the first 6 months, but don't share a bed.[1] For a full checklist, see Creating a Safe and Soothing Sleep Environment for Your Baby.

Should Every Caregiver Place Babies on Their Backs for Every Sleep?

Yes. Parents, grandparents, babysitters and child care providers should all place babies on their backs for naps and nighttime sleep.[3] Consistency matters: when a baby who usually sleeps on their back is placed on their stomach or side, even for one nap, SIDS risk rises sharply, up to 45 times higher in some studies.[2][3] Before another caregiver takes over, show them the sleep space and ask them not to use the side or stomach to help your baby sleep longer.[1]

What if a Grandparent Says, "We Put You on Your Tummy and You Were Fine"?

It helps to be warm rather than trying to win the argument. A generation ago, stomach and side sleeping were widely advised. Research then showed both raised SIDS risk, and rates fell sharply once the advice changed.[2][6] You might say: "Doctors learned something new, and this is what they recommend now. Can you help me by following it, even for naps?"

Should Babies With Reflux or Spit-Up Still Sleep on Their Backs?

Yes. Healthy babies have swallowing and coughing reflexes that help clear fluid. Evidence does not show that back sleeping makes healthy babies more likely to choke, and the AAP recommends back sleeping even for babies with reflux.[11]

Don't try to manage reflux with props that change sleep position. Raising the head of the crib doesn't reduce reflux, and an inclined surface can let a baby slide into a position that blocks the airway.[2][11] A few babies with specific medical conditions, such as certain upper airway problems, may get individual positioning instructions from their doctor. That is a case-by-case medical decision; never switch positions on your own.[2]

The same goes for a stuffy nose. Congestion is not a reason to use the side position or incline the mattress. Ask your pediatrician if congestion affects feeding, and get prompt medical care for any difficulty breathing.[9][12]

What if My Baby Wakes Up as Soon as I Lay Them on Their Back?

This is a big reason many parents are tempted to try the side or tummy sleep position. Frequent waking is normal in infancy, and there's no single proven reason babies wake at the moment they're laid down. The startle (Moro) reflex, a normal newborn response to sudden movement or noise, may be one of several reasons for some newborns. It's strongest in the first month, usually starts to fade after about 2 to 3 months, and is typically gone by 6 months.[13][14] If you swaddle to help calm it, follow the safety steps above: always place your baby on their back, and stop swaddling at the first signs of rolling.[4] Whatever the cause, if your baby wakes as soon as they are placed on their back, comfort them and try laying them down again without changing their sleep position.[3][15]

What Research Suggests Trying

A small 2022 study from Japan looked closely at what happens when mothers lay sleeping babies down. More than a third of the babies became alert again within about 20 seconds of being put down, and the moment their bodies began to separate from their mother's was what most consistently roused them. Babies who had been asleep longer before being laid down were less likely to wake. Based on these results, the researchers proposed sitting and holding your baby for about 5 to 8 minutes after they fall asleep, then laying them down.[16] This was a single small study, and the authors note the approach still needs to be confirmed in larger studies, so think of it as worth a try rather than a guaranteed fix.

One important caution: if you're very tired, put your baby down in their crib or bassinet sooner rather than risk falling asleep with them in your arms, especially on a sofa or armchair.[8][17]

Tips Many Parents Find Helpful

Some parents find it helps to lower their baby slowly, keeping them close to their body until the last moment, and then to rest a hand gently on the baby's chest for a moment. These are common parent tips rather than methods that have been tested in studies, so they may work for some babies and not others.

Frequently Asked Questions About Back Sleeping

Is It Okay if My Baby Turns Their Head to the Side?

Yes. Babies placed on their back often turn their head to one side, and that's normal. It isn't side sleeping: what matters is that your baby's body is lying on its back and nothing soft is near their face. To keep your baby from always facing the same way, switch which end of the crib their head points toward from one week to the next.[3][18]

Will Back Sleeping Give My Baby a Flat Head?

Back sleeping can lead to some flattening, but it’s not a reason to change sleep position. Making sure your baby gets plenty of supervised tummy time while awake is one of the best ways to prevent flat spots. Changing their head direction in the crib each week also helps.[2][18] Don’t use a head-shaping pillow in the sleep space, and talk to your pediatrician if you notice flattening or a head tilt.[1][19]

Is Supervised Tummy Sleeping Safe?

No. Tummy time means your baby is awake and watched. If your baby gets sleepy during tummy time, move them to their sleep space and place them on their back.[1][18]

Should Premature Babies Sleep on Their Backs at Home?

Yes. Babies in the NICU are sometimes placed on their side or stomach for medical reasons while they're closely monitored, but that isn't a model for sleep at home. The AAP recommends moving preterm babies to back sleeping once they're medically stable, well before discharge.[1][2][20] Ask the NICU team to confirm your baby's sleep plan before you go home.

What if My Baby Falls Asleep in a Car Seat, Swing or Stroller?

While it is common for babies to be lulled to sleep by the motion of cars and swings, it is not safe for them to stay asleep in this position. If your baby falls asleep in a car seat, don't panic - simply move them to a safe sleep position on their back as soon as it is safe to do so. Sitting devices aren't safe for routine sleep.[1]

The Bottom Line

Back, never side. Start every sleep on the back, keep the sleep space clear, and respond to rolling based on what your baby can actually do. Share this with everyone who cares for your baby, and ask your pediatrician about anything specific to your baby's health.[1][3]

References

[1] Moon, R. Y., Carlin, R. F., Hand, I., Task Force on Sudden Infant Death Syndrome, & Committee on Fetus and Newborn. (2022). Sleep-related infant deaths: Updated 2022 recommendations for reducing infant deaths in the sleep environment. Pediatrics, 150(1), e2022057990. https://doi.org/10.1542/peds.2022-057990

[2] Moon, R. Y., Carlin, R. F., Hand, I., Task Force on Sudden Infant Death Syndrome, & Committee on Fetus and Newborn. (2022). Evidence base for 2022 updated recommendations for a safe infant sleeping environment to reduce the risk of sleep-related infant deaths. Pediatrics, 150(1), e2022057991. https://doi.org/10.1542/peds.2022-057991

[3] Eunice Kennedy Shriver National Institute of Child Health and Human Development. (n.d.). About back sleeping. Safe to Sleep®. https://safetosleep.nichd.nih.gov/reduce-risk/back-sleeping

[4] Moon, R. Y., & Glassy, D. (2022, July 15). Swaddling: Is it safe for your baby? HealthyChildren.org. https://www.healthychildren.org/English/ages-stages/baby/diapers-clothing/Pages/Swaddling-Is-it-Safe.aspx

[5] Erck Lambert, A. B., Parks, S. E., Cottengim, C., Mohamoud, Y. A., Ly, K. N., Kroelinger, C. D., & Riehle-Colarusso, T. (2026). Characteristics of sudden unexpected infant deaths — United States, 2020–2024. MMWR Morbidity and Mortality Weekly Report, 75(35), 544–550. https://www.cdc.gov/mmwr/volumes/75/wr/mm7535a1.htm

[6] American Academy of Pediatrics Task Force on Sudden Infant Death Syndrome. (2005). The changing concept of sudden infant death syndrome: Diagnostic coding shifts, controversies regarding the sleeping environment, and new variables to consider in reducing risk. Pediatrics, 116(5), 1245–1255. https://doi.org/10.1542/peds.2005-1499

[7] Kim, T. H., Lee, H., Woo, S., Lee, H., Park, J., Fond, G., Boyer, L., Hahn, J. W., Kang, J., & Yon, D. K. (2024). Prenatal and postnatal factors associated with sudden infant death syndrome: An umbrella review of meta-analyses. World Journal of Pediatrics, 20(5), 451–460. https://doi.org/10.1007/s12519-024-00806-1

[8] Eunice Kennedy Shriver National Institute of Child Health and Human Development. (n.d.). Safe sleep environment for baby. Safe to Sleep®. https://safetosleep.nichd.nih.gov/reduce-risk/safe-sleep-environment

[9] Seattle Children's. (n.d.). Breathing trouble. https://www.seattlechildrens.org/conditions/a-z/breathing-trouble/

[10] Cramer, J. (2022, October 21). The ABCs of safe sleep. Johns Hopkins Medicine. https://www.hopkinsmedicine.org/news/articles/2022/10/the-abcs-of-safe-sleep

[11] Porto, A. (2021, November 30). What is the safest sleep solution for my baby with reflux? HealthyChildren.org. https://www.healthychildren.org/English/tips-tools/ask-the-pediatrician/Pages/What-is-the-safest-sleep-solution-for-my-baby-with-reflux.aspx

[12] Moon, R. Y. (2025, December 16). My baby has a stuffy nose. How can I help them sleep safely? HealthyChildren.org. https://www.healthychildren.org/English/tips-tools/ask-the-pediatrician/Pages/my-baby-has-a-stuffy-nose-how-can-i-help-them-sleep-safely.aspx

[13] American Academy of Pediatrics. (2022, March 8). Newborn reflexes. HealthyChildren.org. https://www.healthychildren.org/English/ages-stages/baby/Pages/Newborn-Reflexes.aspx

[14] Pattnaik, P., & Al Khalili, Y. (2025). Moro reflex. In StatPearls. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK542173/

[15] American Academy of Pediatrics. (2022, March 21). How to calm a fussy baby: Tips for parents & caregivers. HealthyChildren.org. https://www.healthychildren.org/English/ages-stages/baby/crying-colic/Pages/Calming-A-Fussy-Baby.aspx

[16] Ohmura, N., Okuma, L., Truzzi, A., Shinozuka, K., Saito, A., Yokota, S., Bizzego, A., Miyazawa, E., Shimizu, M., Esposito, G., & Kuroda, K. O. (2022). A method to soothe and promote sleep in crying infants utilizing the transport response. Current Biology, 32(20), 4521–4529.e4. https://doi.org/10.1016/j.cub.2022.08.041

[17] Moon, R. Y. (2026, September 13). Safe sleep tips for sleep-deprived new parents. HealthyChildren.org. https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/safe-sleep-tips-for-sleep-deprived-parents.aspx

[18] Eunice Kennedy Shriver National Institute of Child Health and Human Development. (n.d.). Tummy time for a healthy baby. Safe to Sleep®. https://safetosleep.nichd.nih.gov/reduce-risk/tummy-time

[19] American Academy of Pediatrics. (n.d.). Head tilt (torticollis). HealthyChildren.org. https://www.healthychildren.org/English/health-issues/conditions/cleft-craniofacial/Pages/Head-Tilt.aspx

[20] Moon, R. Y. (2026, September 11). How to keep your sleeping baby safe: AAP policy explained. HealthyChildren.org. https://www.healthychildren.org/English/ages-stages/baby/sleep/Pages/a-parents-guide-to-safe-sleep.aspx