7 minute readWho invented the 5 S’s of sleep?
We’ve got Dr. Harvey Karp to thank for the 5 S’s of sleep. A pediatrician and child development expert, Dr. Karp is renowned worldwide for developing this technique, first introducing it in his 2002 book The Happiest Baby on the Block.
During his time with UCLA’s child abuse team, Dr. Karp witnessed first-hand how babies were often severely injured, abandoned, or killed — just for crying. Determined to do whatever he could to prevent this, he devoted all his time to figuring out the cause of colic (persistent crying most often seen in infants between 1-4 months of age).
The results of his research were fascinating. In 1981, he learned about the !Kung people of the Kalahari Desert. Among the !Kung, mothers rarely deal with prolonged crying because they spend nearly 24 hours a day holding, feeding, rocking, and jiggling their babies — essentially recreating the comforting sensations of the womb.
After discovering this, Dr. Karp figured that parents need to understand just two things:
Babies are born neurologically immature and need a “fourth trimester” of womb-like care.
Replicating the soothing environment of the womb using simple but effective techniques is the best way to help a crying baby relax.
This second factor is because all tots have a calming reflex — a neurological response that essentially acts as nature’s off-switch for fussiness — and this is where Dr. Karp came up with the 5 S’s.
What are the 5 S’s of sleep for babies?
The 5 S’s stand for Swaddle, Side or Stomach Position, Shush, Swing, and Suck — quite a mouthful, but it makes for a great tongue twister!
Now, let’s take a look at each of the S’s in detail:
Swaddle
Even us adults find it hard to sleep unless we’re feeling snug and cozy, and while we might not have any memories of being swaddled as babies, many will remember the safety and comfort of being ‘tucked in’ at bedtime.
Swaddling — that is, wrapping your tot in a blanket to create a cocoon-like environment, mimicking the confined conditions of the womb — is the first of the S’s. It’s highly effective at reducing crying and can even prevent your baby from startling themselves awake, by reducing the Moro reflex.
To swaddle safely:
Use a soft, breathable blanket and wrap it around your little one securely but not too tightly.
Make sure your baby’s hips can move freely to avoid any risk of hip dysplasia.
Avoid covering your baby’s face or allowing the blanket to loosen, as this can pose a suffocation risk.
Be aware, too, that it’s not recommended to swaddle your baby for unsupervised sleep, as it’s thought that it may increase the risk of SIDS. Similarly, it’s only suitable for babies that aren’t yet able to roll over — some babies develop this ability around 3-4 months, and you should avoid swaddling as soon as your baby displays rolling abilities (or by 16 weeks at the latest).
It’s equally important to remember that not all babies enjoy being swaddled, so you should pay attention to their cues and not force swaddling upon them if they appear agitated or uncomfortable — it isn’t right for every baby, and that’s okay.
Side or Stomach Position
Babies often feel more comfortable when placed on their side or stomach while being soothed. Like swaddling, this position helps reduce the Moro reflex and can be especially helpful for babies with colic or reflux.
It’s also worth mentioning that while the side or stomach position is a great way of calming your baby down when they’re crying, you should always place your little one on their back when it’s time for them to sleep.
Shush
Nobody likes to be shushed — apart from babies. “Shushing” is a surprisingly potent way of calming your tot, perhaps thanks to the fact the sound mimics the white noise they would’ve heard in the womb, where blood flow and amniotic fluids coalesce into a constant whooshing sound. Dreamy!
You can shush your tot the old-fashioned way, use a purpose-built white noise machine, or find a suitable white noise soundtrack on YouTube. Just make sure the volume isn’t too loud — anything over 60dB could damage your tot’s sensitive little ear drums — and if you’re using a white noise machine, it should be placed at least 2 meters from their crib.
Swing
There’s a reason “Rock-a-Bye-Baby” is such a popular lullaby… Gentle, rhythmic motion — such as rocking or swinging — can have an almost magical effect on a fussy tot. This movement mimics the sensation of being rocked in the womb, creating a deep sense of safety, security, and relaxation.
Research proves that rocking — whether in your arms, or with a smart bassinet — can reduce crying, hasten sleep onset, and even improve overall sleep quality. However, if you’re trying to soothe a wailing tot, you’ve got to adjust your technique accordingly. Instead of slow and steady, use faster, smaller motions, moving no more than an inch or two back and forth. Just remember to support your baby’s head and neck at all times.
Interestingly, rocking isn’t just beneficial for your little one, either. Studies also show that adults who were rocked before bedtime find it easier to drift off (so consider investing in a hammock if you often find yourself tossing and turning!)
For this ‘S’, try:
Rocking your baby in your arms.
Wearing your baby in a sling or carrier while walking.
Using a baby swing (always follow safety guidelines and avoid prolonged use).
Just be sure to transition your baby to a stationary sleep environment once they’re ready for a nap. You should never let your baby sleep in a swing, for example — instead, transfer them to a firm mattress when they’re tired.
Suck
The final S really sucks…
Research shows that non-nutritive sucking (sucking on a pacifier, for example) can reduce crying and help regulate a baby’s heart rate. And better yet, it may also reduce the risk of SIDS when used during sleep.
If you’re breastfeeding though, try to establish a strong nursing routine before introducing a pacifier to avoid nipple confusion, otherwise your baby may get fussy when making the switch from teat to breast.
What should I do if the 5 S’s technique doesn’t work?
While we’re firm believers of Dr. Karp’s techniques, we also understand that what works for one tot won’t necessarily work for the next. Babies are complex little creatures, so don’t be discouraged if you’ve tried all of the steps above and your baby is still in miniature foghorn mode.
If this is the case, try these extra tips and tricks:
Make sure your baby isn’t hungry, has a clean diaper, and isn’t too hot or cold. Sometimes the solution is simpler than it seems.
They might be unwell. Look for signs like fever, rash, or vomiting, and consult your pediatrician if you’re concerned.
Try modifying your technique. If swaddling isn’t working, have you tried combining it with white noise? What about singing a lullaby while swinging?
It’s natural to feel stressed when your baby won’t stop crying, but remember that babies are highly attuned to their parents’ emotions. Try to stay calm and patient — your baby will sense this and may feel more at ease.
Reach out for support. Don’t hesitate to ask for help, whether from a partner, family member, or friend. Sleep deprivation can take a toll on your mental health
Mastering the 5 S’s won’t turn your tot into a quiet, peaceful sleeper overnight (we’ll let you know when we figure out how to achieve that!), but it will arm you with a set of powerful, scientifically-backed tools to navigate those early, challenging few months.
Sleepless nights suck (pun absolutely intended), but every evening spent soothing your troubled tot brings you closer to understanding the tricks and techniques your baby responds to best. Hang in there — you’ve got this!
Reviewed by Rosey Davidson, Sleep Consultant, founder & CEO, in December 2024.