Baby Sleep Hack: How Swaddling Works (According to Science)

One of my favorite baby sleep hacks is swaddling. With the right tools (discussed in another post), it is actually quite easy. Here I discuss the science and history behind swaddling.

Scientific Studies:

Most (though not all) scientific studies have found that swaddling helps babies sleep. It is great that swaddling is easily studied in the lab! Most of these studies were done in the lab for naps (not overnight sleep). One non-laboratory study giving parents materials on swaddling versus not giving materials to parents was found to be not effective. (There could be many reasons for why that study was not effective.)

Here are some of the benefits for babies of swaddling found in the scientific studies:

1. Arouse less, startle less
2. Sleep longer
3. More likely to return to sleep on their own
4. Soothes infants (not as quickly as pacifier but still does)
5. Improve motor skills in preterm babies
6. Keep them warm

History:

Swaddling was nearly universal before the 18th Century across the world. It very possibly evolved multiple times. In North America, cradle boards (picture here) were used for both sleep and transportation of babies. Swaddling is not as common in really hot and humid areas like Africa. This is likely because it can lead to skin infections in hot and humid areas. Slings are more common in hot climates.

Swaddling fell out of favor in Eastern and Western Europe in the 19th and 20th centuries. Swaddling was seen as putting your baby in prison. A revival is happening now. It is standard practice in the medical community to recommend swaddling, at least in the United States. (Though I would argue that the training methods for swaddling taught by hospitals are extremely out-of-date). Baby slings and carriers (some that look like a lot the cradle board above) are on the market today. Here is an example of baby carrier sold by Osprey.

Osprey Packs_SS24_Poco Plus Child Carrier – Kids_OSPZ18A_OSPZ18B on Vimeo

Safety:

Swaddling is safe when done properly; however, there are some risks. Swaddling can both increase and decrease the risk of SIDs. It can reduce the risk of SIDs if the baby is put on their back while swaddled (before they can roll over). However, it can also increase the risks of SIDS if baby is not placed on their back, or the baby can roll over while swaddled.

Safety risks when swaddling:

1. SIDs: can increase SIDs risk if baby not on back or can roll over while swaddled
2. hip dysplasia: especially if other risk factors; just swaddle arms and not legs to avoid this
3. Increase in respiratory infections (not seen in the US but seen in China and other countries, perhaps because they swaddle more tightly or frequently than in the US).
4. Overheating

When to start swaddling:

You can start almost immediately after skin-to-skin contact. Could be issue if start swaddling when baby is older (3+ months) but not a lot of evidence here.

When to stop swaddling:

Stop swaddling when your baby can roll over while swaddled. Most cultures stop between 3 and 12 months. 9 months is when babies outgrow the jerk reflux. If your baby rolls over before 9 months, you can use a transitional swaddle. We used a transitional swaddle for our kids. By 9 months, we stopped using a transitional swaddle and our babies slept through the night just fine.

Amazon.com: Baby Merlin’s Magic Sleepsuit Transition Product – 6-9 Months Swaddle Transition Sleepsuit – Soft Cotton Material with Double Zipper for Easy Diaper Changes – Promotes Safe Sleep for Babies – Lavender : Baby

My favorite reference on swaddling:

Swaddling: A Systematic Review | Pediatrics | American Academy of Pediatrics