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How breast milk can impact the quality of your baby’s sleep—and yours

By Cradlewise Staff

It’s a truth universally acknowledged that parents (especially mothers) of newborns are highly deprived of sleep. Whether you’re breastfeeding, formula feeding, or doing a combination of both, chances are that you won’t be getting your good old seven to eight-hour stretch of uninterrupted sleep until your baby is slightly older. 

However, breast milk plays a pivotal part in the quality of your little one’s sleep, and it’s not just related to hunger. Breast milk also plays a huge role in how well you sleep. 

Cradlewise and Lilu experts came together to help you learn more about the relationship between breastfeeding and sleep— yours and your baby’s.

Can breast milk affect baby sleep?

For nursing families, breast milk is your baby’s go-to food and only nutrition for the first six months of life . And while you know that it helps them grow and provides them with life-long immunity, often, most people aren’t aware of the impact breast milk has on babies’ sleep. For breastfeeding babies, breast milk helps reinforce the sleep-wake cycle known as our circadian rhythms. Here’s how it works:

Any parent can testify that newborns don’t have a sense of day and night. As adults, we know when it’s time to wake up and go to bed. Our bodies have built-in clocks, also known as circadian rhythms, that are synced with the sun, so we get sleepy after sunset and more alert around sunrise.

Babies dont have circadian rhythm breast milk

Babies are not born with these internal clocks, and they only start developing their circadian rhythm somewhere between three to four months of age. If you’re nursing, breast milk plays a key role in this development.

The composition of breast milk is dynamic in nature—as in, it changes throughout the day to meet the nutritional and other needs of the baby. Your morning breast milk has a hormone called cortisol in it, which helps babies become alert and awake during the day. And your breast milk in the evening is high in a hormone called melatonin (aka the sleep hormone), which helps the baby fall asleep.

Over the course of the first three to four months of life, these hormones train your baby’s internal clock. Soon, they will start forming mature sleep patterns of feeling drowsy after sunset and awake at sunrise.

As Lilu’s expert lactation consultant Torey Potter (RN, BSN, IBCLC) explains,  the naturally-occurring ingredients in breast milk play an important role in your baby’s sleep.

Cortisol and melatonin are not present in infant formula, however several nutrients and micronutrients, as well as fat, aid in circadian rhythm. Breast milk also varies in the content of certain hormones and nutrients depending on the time of day, which aids in infant sleep and circadian rhythm.
– Torey Potter (RN, BSN, IBCLC)

Cortisol and melatonin are not present in infant formula, however several nutrients and micronutrients, as well as fat, aid in circadian rhythm. Breast milk also varies in the content of certain hormones and nutrients depending on the time of day, which aids in infant sleep and circadian rhythm.”

Torey Potter (RN, BSN, IBCLC)

How breastfeeding helps mothers sleep 

Prolactin and oxytocin are two hormones that directly affect breastfeeding. 

The prolactin in breast milk helps induce sleep in the breastfeeding mom. When you breastfeed your baby, this hormone gets released into your bloodstream. So right after feeding, this hormone helps you fall asleep quickly and easily. The best part? It works the same whether you’re taking a nap or going to bed for the evening.

Another benefit of prolactin is that it helps calm your nervous system, which also makes it easier for you to not only fall asleep, but stay asleep. Prolactin also may help mothers feel calmer during the postpartum period.

Especially when new moms are room-sharing with their newborn, as recommended by the American Academy of Pediatrics (AAP) during the first six months of life, breastfeeding mothers may be active and awake for shorter periods during the night, making it easier to fall back to sleep. 

Do breastfeeding mothers get more sleep?

A mom breastfeeding her baby while pumping her breast milk

In a 2014 study, women who breastfed exclusively averaged 30 minutes of extra nighttime sleep compared with women who fed their infants formula at night. That said, both formula-fed and breastfed babies in the study still woke up during the night to feed, resulting in about the same amount of interrupted sleep. 

According to Rachel Mitchell, Certified Sleep Specialist and CEO of My Sweet Sleeper, “If your baby has trouble sleeping at night you may have been told to add cereal to their bottle or to start supplementing with formula in order to help them get longer stretches. But multiple studies have shown there is no such correlation, and actually have shown that breastfeeding mothers and babies tend to get more sleep overall.”

While we know that not all mothers can or choose to breastfeed, studies have shown that they may end up getting more sleep, as Mitchell notes: “While there are a few reasons for this, one of the primary reasons that breastfeeding mothers may get more sleep is because breastfeeding naturally releases the hormone melatonin and oxytocin, which can help you relax.”

Regardless of how parents feed their newborns, however, it’s a fact that new parents lose about 350 hours of sleep in the first year of parenthood. And according to this study by the Sleep Research Society, there’s a “sharp decline in sleep satisfaction and duration in the first months postpartum… neither mothers’ nor fathers’ sleep fully recovers to prepregnancy levels up to 6 years after the birth of their first child.”

Do formula-fed babies sleep longer at night?

There’s little evidence to support the claim that formula-fed babies sleep longer than breastfed babies, in terms of the total amount of sleep. However, since breast milk is more easily digestible than formula, babies who breastfeed are likely to wake up more frequently than formula-fed babies, as they will get hungrier faster. However, the melatonin in breast milk will facilitate their sleep, so right after the feeding, they’ll go back to sleep easily.

Does lack of sleep reduce breast milk?

Yes. There are a lot of things that can reduce your breast milk supply, and lack of sleep is one of them.

Oxytocin (along with prolactin) is a pivotal breastfeeding hormone. Oxytocin causes your milk to flow from your breasts. When you sleep less, your body becomes stressed—which releases adrenaline in your system, and this adrenaline inhibits oxytocin. So feeling sleep deprived, stressed, or anxious may reduce your breast milk supply.

According to Mitchell, the fourth trimester is a huge adjustment for the entire family, but especially for mom and baby.

Women undergo a range of hormone changes while also meeting the demands of their newborn babies. Breastfeeding mothers, specifically, may notice that they have trouble maintaining their supply if they are chronically sleep-deprived and/or stressed due to the rise in cortisol levels which can hinder breast milk production.
– Rachel Mitchell

Women undergo a range of hormone changes while also meeting the demands of their newborn babies. Breastfeeding mothers, specifically, may notice that they have trouble maintaining their supply if they are chronically sleep-deprived and/or stressed due to the rise in cortisol levels which can hinder breast milk production.”

Rachel Mitchell

This is one of the reasons why it is so important for women to have support from their partner, their family, and their community, so they can properly care for themselves while taking care of their baby. 

Will feeding my baby more make him sleep longer?

Your baby will be able to sleep slightly longer at night if their tummy gets filled during the day, making them less hungry when they doze off.

But your baby’s sleep depends more on their developmental stage than on how much they eat. For example, a newborn baby will need to be fed three to five times each night until two months of age (and perhaps even more frequently than that during the early weeks). At three to four months of age, they will need three to four nightly feedings. 

“Feeds begin to space out a bit around one month, but the baby should still be getting at least eight feeds per day, until about four months when it may decrease to 6-8 times per day,” notes Lilu lactation expert Torey Potter, “After nine months, it may be as few as four times per day but could still be as many as eight.”

FAQs

Q: Does breastfeeding drain your energy?

A: Yes, breastfeeding does drain your energy. When your body is producing milk, it requires a lot of energy, burning around 500-700 calories extra per day.

Q: Does sleeping through the night reduce milk supply?

A: No, your milk supply doesn’t reduce when your baby sleeps through the night. As your baby grows older, they will able to take in more milk during the day as they sleep more at night. 

According to Lilu’s Lactation Expert, Torey Potter, “Full breasts send the body a signal to slow down on milk supply. However, a baby sleeping through the night shouldn’t reduce milk supply so long as the breasts are being regularly emptied throughout the rest of the day and the longer interval between emptying doesn’t happen very suddenly.”

Q: Do you produce more breast milk while sleeping?

A: Yes. The prolactin levels in breastfeeding women are much higher at night, especially in the early morning hours—leading to more milk. If you’re pumping to build up a supply for work, try to do it in the morning when your supply is the highest.

Q: Will feeding a baby more make him sleep longer?

A: Torey Potter weighs in decisively on this question: “No, feeding a baby won’t make them sleep longer. Young babies need to eat frequently and it’s biologically normal for young babies to wake to feed overnight.”

Newborns should be fed at least every three hours until they get back to their birth weight, and after that, they can be allowed to sleep, but will still probably not sleep longer than about four hours at a time.

Q: Is breastfeeding while lying down a good idea?

A: Yes, it’s a great way to rest your body while feeding, and many moms find it very comfortable and restful once they get the hang of it,” Torey Potter says. “They should be mindful of safe bedsharing practices while side lying to feed their baby if they think they might fall asleep. See the Safe Sleep Seven.”

FAQs

Q: Does breastfeeding drain your energy?

A: Yes, breastfeeding does drain your energy. When your body is producing milk, it requires a lot of energy, burning around 500-700 calories extra per day.

Q: Does sleeping through the night reduce milk supply?

A: No, your milk supply doesn’t reduce when your baby sleeps through the night. As your baby grows older, they will able to take in more milk during the day as they sleep more at night. 

According to Lilu’s Lactation Expert, Torey Potter, “Full breasts send the body a signal to slow down on milk supply. However, a baby sleeping through the night shouldn’t reduce milk supply so long as the breasts are being regularly emptied throughout the rest of the day and the longer interval between emptying doesn’t happen very suddenly.”

Q: Do you produce more breast milk while sleeping?

A: Yes. The prolactin levels in breastfeeding women are much higher at night, especially in the early morning hours—leading to more milk. If you’re pumping to build up a supply for work, try to do it in the morning when your supply is the highest.

Q: Will feeding a baby more make him sleep longer?

A: Torey Potter weighs in decisively on this question: “No, feeding a baby won’t make them sleep longer. Young babies need to eat frequently and it’s biologically normal for young babies to wake to feed overnight.”

Newborns should be fed at least every three hours until they get back to their birth weight, and after that, they can be allowed to sleep, but will still probably not sleep longer than about four hours at a time.

Q: Is breastfeeding while lying down a good idea?

A: Yes, it’s a great way to rest your body while feeding, and many moms find it very comfortable and restful once they get the hang of it,” Torey Potter says. “They should be mindful of safe bedsharing practices while side lying to feed their baby if they think they might fall asleep. See the Safe Sleep Seven.”

Sources:

  1. Breastfeeding baby at night. 2014. NIH.Nighttime Breastfeeding Behavior Is Associated with More Nocturnal Sleep among First-Time Mothers at One Month Postpartum.”
  2. Post-partum sleep satisfaction. 2019. NIH. “Long-term effects of pregnancy and childbirth on sleep satisfaction and duration of first-time and experienced mothers and fathers.” 
  3. Energy consumption during breastfeeding. La Leche League International. “Weight Loss–for Mothers.”
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