All babies cry—and that’s a good thing. How else would we know if our helpless infants were cold, hungry, lonely, or in pain? Traditionally, parents have been encouraged to simply keep their chins up and wait until the baby grows out of it. But that’s easier said than done. Even if you could do it, it could be detrimental. Research has repeatedly shown that persistent infant crying—and the sleep deprivation that often goes hand-in-hand with those tears—can increase a new parent’s chances of postpartum depression (PPD). So, learning how to soothe your little one’s crying is important for everyone! And…it’s not as tricky as you think. During my work as a practicing pediatrician, I discovered a technique I call the 5 S’s and it’s the key to calming babies and helping them sleep. Today, thousands of educators across America and the world have been trained to teach the 5 S’s in hospitals, parenting clinics, military bases, and more.  

So, what exactly are the 5 S’s? And why are they so important? Glad you asked! Here’s everything you need to know about the 5 S’s for soothing babies.

Why We Need the 5 S’s: Crying takes a toll on babies and parents

Typically, babies get increasingly irritable around sundown and that can continue for hours. (Hello, witching hours!) No wonder parents get concerned, frustrated, and very, very tired.

Exhaustion triggered by persistent crying creates a huge stress in families. It chips away at your health, it shortens your fuse, slows your thinking, creates distance between you and your partner…and increases risk of postpartum depression in both parents. It also puts babies in danger when a wiped-out parent falls asleep with a baby in their arms, on an unsafe couch or a bed, which increases a baby’s risk for SIDS and infant suffocation.

Where the 5 S’s Come From: My ‘Aha!’ Moment on Calming Babies

Years ago, when I was working on the child abuse team at UCLA, I saw so many babies come in who were severely injured—even killed—for the simple offense of crying. At the time, I was deeply curious about what medical doctors had not been able to figure out—the cause of colic (severe persistent crying seen among babies 1 to 4 months of age). I began reading everything I could about this centuries-old medical puzzle. Then in 1981 I learned about the !Kung San of the Kalahari Desert, whose mothers usually calm their fussy babies in under a minute! Their secret? The !Kung mothers hold their infants almost 24 hours a day, constantly feeding, rocking, and jiggling them. In essence, they mimic the womb experience for months. The more I thought about it, the more I realized that we could be as successful as !Kung parents. We just had to adopt two new ideas:

  • All babies are born three months early. Thanks to evolutionary changes, human babies are born about three months before they’re technically “ready.” In fact, they had to be born three months early because a baby’s developing brain and skull have gotten so big by the end of the third trimester that they can barely safely fit through the birth canal! Think about it: Newborn horses can run within an hour of birth...but our mushy little babies are completely helpless! A virtual fourth trimester, complete with womb sensations (soft touch, jiggly motion, snug holding, etc.) may be just what babies need to feel safe and calm.

  • Babies have an innate calming reflex. I discovered that the rhythms babies experience inside the womb—the jiggling and the constant hum of noise, for example—trigger a reflex that keeps babies relaxed. This calming reflex is a neurological response that develops deep in a baby’s brain months before they’re born that’s basically nature’s “off switch” for fussing and “on switch” for sleep.

While I may have been the first to put these ideas together in my bestselling book The Happiest Baby on the Block, the truth is, parents everywhere have long turned to similar womb-mimicking tricks to soothe their babies. Whether parents realized it or not, going for car rides and turning on the vacuum cleaner to calm babies copycats the womb and triggers the calming reflex.

The Basics of the 5 S’s Method for Soothing Babies

Parents around the world have invented all kinds of variations on the calming womb-like sensations that I’ve dubbed the 5 S’s: Swaddle, Side-Stomach Position, Shush, Swing, and Suck. Here’s what each of the 5 S’s are, what they do, and how to use them to calm and comfort your little one.

The First of the 5 S’s: Swaddle

Dr. Harvey Karp's 5 S's: Swaddling

Swaddling, a cornerstone of calming, recreates the gentle hug and security of the womb, which increases sleep. It also decreases the startle reflex, where babies’ flailing arms can bonk them in the face and wake them up. Plus, wrapped babies can respond faster to the other 4 S’s and stay soothed longer because their arms can’t wriggle around. To swaddle correctly, wrap your baby like a mini burrito with their arms snug and straight at their sides. But let Baby’s hips be loose and flexed. You can use a large square lightweight blanket or my Sleepea 5-Second Swaddle, which takes all of the guesswork out of swaddling. Babies should only be swaddled during fussing and sleep and swaddling needs to stop once your baby can roll over. (SNOO babies can remain safely swaddled until they graduate to the crib.)

The Second of the 5 S’s: Side or Stomach Position

Activate this S by holding your baby on their stomach or side—or even over your shoulder. However, it’s very important to note that you can hold babies on their side or stomach, but it is NOT safe to place a baby on the side or stomach to sleep. The back is the only safe position for sleeping.

The Third of the 5 S’s: Shush

Dr. Harvey Karp's 5 S's: Shushing

Contrary to popular belief, babies don’t need total silence to sleep. In fact, they prefer a noisy environment. In the womb, babies listened to the sound of blood flow that was louder than a vacuum cleaner 24/7! The best way to recreate that sound outside of the womb is with white noise. But not all white noise is created equal. For example, hissy fans and ocean sounds often fail to calm babies because they lack the womb’s consistent, rumbly quality. To make sure you’re giving your little one the just-right sleep sounds, try my award-winning SNOO bassinet, SNOObear, SNOObie, or our Happiest Baby SNOO sounds download, each contain specially engineered white noise to calm crying and boost sleep.

The Fourth of the 5 S’s: Swing

Dr. Harvey Karp's 5 S's: Swinging

Life in the womb is very jiggly. Babies are just bopping around in there for nine months as Mom jaunts down the stairs, takes a walk, or does just about anything! And all the rockin’ and rollin’ is calming. Research shows that rocking—and rocking bassinets—reduce crying, hasten sleep onset, and improve overall sleep quality. While slow rocking is perfect for keeping quiet babies calm, you need to use faster, tiny motions to soothe a crying infant mid-squawk. I call this calming motion the “Jell-O head jiggle.” To do it, support your baby’s head and neck, keep your motions small, and move no more than one inch back and forth. (For the safety of your infant, never, ever shake your baby in anger or frustration.) While many parents are tempted to keep the rocking going all night long in a baby swing, that’s very dangerous. (Baby’s head can flop forward, possibly obstructing their airway, causing suffocation.) For safe sleep, babies should always be on their backs, on firm, flat surfaces. My SNOO Smart Sleeper keeps babies securely on their backs so they can safely experience all-night rocking.

The Fifth of the 5 S’s: Suck

Dr. Harvey Karp's 5 S's: Sucking

Sucking is “the icing on the cake” of calming. Many fussy babies relax into a deep tranquility when they suck. That’s because sucking lowers Baby’s heart rate, blood pressure, and stress levels. It’s amazing how much pleasure sucking can bring your little one! If you’re breastfeeding, wait until nursing is well-established before introducing a pacifier.

How The 5 S’s Relate to Two More Favorite S’s—Sleep and SNOO!

For centuries, extended family would be the ones to help new parents with so much of the middle-of-the-night rocking and shushing and snug swaddle-like cuddling—three integral parts of the 5 S’s. But as that village disappeared, so did the help. That’s when I realized technology could step in and assist parents with implementing these age-old comforting cues. So, I teamed up with renowned MIT engineers to create SNOO, a responsive baby bassinet that uses safe swaddling, shushing, and swinging to help calm babies and ease them into sleep. Research shows swaddling, sound, and movement work equally well for soothing babies, whether it comes from SNOO or a loving adult. Moreover, SNOO’s soothing can add 1 to 2 hours of infant sleep each night. Parents especially love when it quickly calms babies for those 2am wakings! 

What to Do If the 5 S’s Aren’t Working

The 5 S’s are incredibly effective at calming most babies. But if the 5 S’s don’t seem to be helping your little one, here are some other things to consider:

  • Does your baby have a little problem? If your little one is hungry, gassy, wet, or lonely, the 5 S’s aren’t what your baby needs! Fortunately, little problems like these are usually obvious and easy to resolve.

  • Does your baby have a bigger problem? Less than 5% of colicky babies have an underlying medical cause of their crying, such as food intolerance, urinary infection, or stomach acid reflux. If you suspect this might be behind your bub’s distress, reach out to your baby’s pediatrician.

  • Are you doing the 5 S’s correctly? From my experience, if the S’s aren’t working for your baby, it’s a good bet that your frantic little one either needs a couple more S’s or you need to revise your technique a little. For example, if you’re just using white noise and swaddling, try offering your baby a pacifier, too. (Here’s how to help your baby take the paci.) And to make sure you’re doing the S’s exactly right, by streaming The Happiest Baby on the Block 5 S's how-tos.

For even more on the 5 S’s, check out:


Side or Stomach Position




About Dr. Harvey Karp

Dr. Harvey Karp, one of America’s most trusted pediatricians, is the founder of Happiest Baby and the inventor of the groundbreaking SNOO Smart Sleeper. After years of treating patients in Los Angeles, Dr. Karp vaulted to global prominence with the release of the bestselling Happiest Baby on the Block and Happiest Toddler on the Block. His celebrated books and videos have since become standard pediatric practice, translated into more than 20 languages and have helped millions of parents. Dr. Karp’s landmark methods, including the 5 S’s for soothing babies, guide parents to understand and nurture their children and relieve stressful issues, like new-parent exhaustion, infant crying, and toddler tantrums.

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Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. If you have any medical questions and concerns about your child or yourself, please contact your health provider.