Side sleeping or back sleeping; which one is actually safer?
Babies do not come with instruction manuals, but they certainly come with plenty of opinions. Grandma might swear by stomach sleeping, your best friend insists on back sleeping, and your little one seems determined to snooze on their side.
So, who is right? Does sleep position really matter that much?
We know you just want what is best (and safest) for your baby. Let’s dig into the facts, bust a few myths, and clarify the safety guidelines for your little one’s sleep habits.
Key Takeaways
- Back is best: Placing your baby on their back is the single most effective way to reduce the risk of Sudden Infant Death Syndrome (SIDS).
- Side sleeping risks: Sleeping on the side can lead to choking, rolling onto the stomach, color changes, and flat spots on the head.
- The rolling rule: You must place your baby on their back until they are 1 year old, or until they can consistently roll from tummy to back and back to tummy on their own.
- Safety first: Avoid sleep positioners, wedges, and loose bedding; instead, use a firm mattress and a sleep sack to keep your baby safe.
What Is SIDS?
The number one reason pediatricians insist your child sleeps on their back is to reduce the risk of Sudden Infant Death Syndrome, commonly known as SIDS.
SIDS is a diagnosis of exclusion given when a child under the age of 1 dies suddenly with no other explanation. It is terrifying because it happens without warning. Sadly, it remains a leading cause of death for infants between 1 month and 1 year old (1).
For decades, doctors have researched ways to decrease these tragedies. In the 1970s and 80s, stomach sleeping was encouraged because doctors believed it prevented choking if a baby vomited. However, SIDS cases rose sharply during that era.
In 1992, the American Academy of Pediatrics (AAP) launched the “Back to Sleep” campaign, recommending back sleeping to reduce SIDS risks (2).
The results were undeniable. SIDS deaths dropped from 130.1 cases per 100,000 live births in 1990 to 39.4 in 2015 (3).
This data is why your baby should never sleep on their stomach. But what about side sleeping? Is that a happy medium?
Unfortunately, the answer is no. Side sleeping poses several specific risks.
Risks Associated With Side Sleeping
Side sleeping might look more comfortable, but it is unstable. A baby placed on their side has a smaller base of support, making it very easy for them to roll onto their stomach (which is dangerous) or get into a position that compromises their airway.
Here are the specific issues side sleeping can cause.
1. Plagiocephaly (Flat Head Syndrome)
Plagiocephaly occurs when a flat spot develops on your baby’s head (4). Because infant skulls are soft and pliable, consistent pressure on one spot can cause flattening.
While usually cosmetic, it is something you want to avoid. If you notice a flat spot, talk to your doctor.
- Mild cases: Doctors usually recommend “repositioning” (turning the baby’s head to the non-flat side) and plenty of supervised tummy time while awake.
- Severe cases: Your pediatrician might recommend helmet therapy to correct the skull shape.
2. Harlequin Color Change
This is a rare but startling condition where the side of the body the baby is lying on turns red, while the upper side remains pale. It creates a distinct line down the center of the body.
It affects roughly 10% of newborns and is usually benign. The color typically returns to normal minutes after the baby moves (5). Doctors believe it relates to the immaturity of the autonomic nervous system affecting blood vessel dilation.
3. Choking Hazards
Contrary to old beliefs, back sleeping is actually safer for choking than side or stomach sleeping. When a baby is on their side, gravity can cause the trachea (windpipe) to twist or compress, making breathing difficult (6).
4. Rolling Into Danger
This is the biggest risk. If a baby is placed on their side, gravity works against them. It takes very little effort to roll from a side position onto their stomach. If your baby is not strong enough to roll back, they can become trapped face-down against the mattress, significantly increasing the risk of suffocation and rebreathing carbon dioxide.
5. Torticollis
Torticollis is a tightening of the neck muscle that connects the head to the collarbone. It can develop if a baby constantly sleeps with their head turned to one side. This can limit their range of motion and lead to abnormal muscle development. Physical therapy is often required to resolve it (7).
What Is the Newborn Curl?
You might notice that in the first few weeks of life, your newborn naturally curls onto their side when placed on their back. This is called the “Newborn Curl.”
It is a physiological reflex left over from being crunched up in the womb. Because their flexor muscles are stiff, their legs pull up and their body tilts to the side.
- Is it safe? Generally, yes, as long as you place them on their back initially.
- When does it stop? This reflex usually disappears within the first few weeks as their muscles relax and gravity takes over.
Even if your baby does the newborn curl, you must continue placing them on their back. Do not use wedges or rolled towels to prop them; just let them uncurl naturally over time.
When Is Side Sleeping Safe?
There is a “golden rule” for sleep positions: You should place your baby on their back for every sleep until they are 1 year old.
However, once your baby is strong enough to consistently roll from tummy to back and back to tummy on their own, you do not need to panic if they flip over.
At this stage (usually around 4 to 6 months), their airway protection mechanisms and neck strength are developed enough that they can choose their own sleep position safely. If you put them on their back and they roll to their side or stomach, it is okay to leave them there.
How To Encourage Back Sleeping
If your baby keeps trying to twist to their side before they are developmentally ready, it can be stressful.
Here are proven tips to keep your little one safely on their back.
1. Use a Swaddle (Safely)
Swaddling mimics the womb, suppressing the startle reflex and making your baby feel secure. A snug swaddle can prevent newborns from curling onto their sides or startling themselves awake.
Important Warning: You must stop swaddling the moment your baby shows signs of trying to roll over (usually around 8 weeks or sooner). If a swaddled baby rolls over, they cannot use their arms to push up, which is a major suffocation risk.
2. Use a Sleep Sack
Once the swaddle phase is over, transition to a wearable blanket or sleep sack. These keep the baby warm without the need for loose blankets (which are a safety hazard). Some sleep sacks are designed to provide a cozy feeling that may reduce the urge to wiggle into a side position.
3. A Bare, Firm Crib
Your baby’s sleep surface should be firm and flat. Do not use pillows, crib bumpers, or rolled-up blankets to “prop” your baby in place.
While it might seem helpful to wedge them so they cannot roll, the CPSC and CDC strongly advise against sleep positioners (8). These items can cause entrapment and suffocation. A bare crib is the safest crib.
4. Try a Pacifier
Offering a pacifier at nap time and bedtime has been shown to reduce the risk of SIDS. While it doesn’t physically hold them on their back, it can help soothe them into sleep without them feeling the need to curl up on their side for comfort.
5. Consistency Is Key
Babies thrive on routine. If your baby is struggling to settle on their back, soothe them until they are calm, but keep placing them back down in that position. Eventually, their body will adjust, and they will learn that lying on their back signals sleep time.
FAQs
Why Does My Newborn Keep Rolling on His Side?
This is likely the “newborn curl,” a reflex from their time in the womb. It usually disappears within the first few weeks. Always place them on their back to start; do not use props to hold them in place.
Can Newborns Sleep on Their Side In a Swaddle?
No. Swaddled babies must always be on their backs. If a baby rolls to their side or stomach while swaddled, they cannot use their arms to reposition, creating a high risk of suffocation.
Does Side Lying Count as Tummy Time?
No. Tummy time specifically requires the baby to be on their stomach while awake and supervised. This strengthens the neck and shoulders. Side-lying helps with motor skills but does not replace the benefits of tummy time.
What Age Can Babies Sleep on Their Side?
Babies can safely sleep on their side only after they can independently roll from back to tummy and tummy to back (usually around 4 to 6 months). Always consult your pediatrician if you are unsure.
Is Side Sleeping Safe for Babies With Reflux?
Generally, no. The AAP still recommends back sleeping for babies with GERD (reflux). Studies show back sleeping does not increase choking risks, even for babies with reflux, and is safer than stomach or side sleeping.
In Conclusion
Sleep safety can feel overwhelming, especially when you are exhausted. But remember: Back is Best.By keeping the crib bare, avoiding positioners, and consistently placing your baby on their back, you are doing the best possible job protecting them. Before you know it, they will be rolling all over the place and choosing their own comfortable spot!
