We have a cultural obsession with infant sleep.  It is not healthy and it is not reasonable, but we have it.  It has led to the proliferation of sleep training and parents who are terrified they have broken babies or are horrid parents because their babies wake and nurse throughout the night.  If you have an orchid child to boot then you’re probably even more down on yourself because they won’t leave your side.

There’s lots that’s wrong with this obsession, but one of the worst side effects is how we have thrown breastfeeding under the bus in favour of sleep.  We:

  • Tell families not to nurse to sleep because it will create bad habits
  • Recommend formula top-ups because it might help baby sleep more
  • Suggest that babies shouldn’t be nursing overnight past a certain age
  • Recommend spacing feeds further apart to try and keep babies from waking for milk

It’s not just from other parents either, but breastfeeding has become a central target in “behavioural interventions” on sleep.  Controlled crying inherently puts breastfeeding at risk, but it’s not considered as such because most people don’t have the awareness of how crucial those night feeds are, but others actually actively look to reduce nursing as a means to improve sleep.  For example, James-Roberts and colleagues[1] created an intervention for the first three months to improve sleep and infant crying and guess what it involved?  That’s right, focal feeds, stretching intervals of feeds, and minimizing contact at night (impossible when nursing on demand), all things pertaining to breastfeeding.  More recently there has been speculation that the early introduction of solids may help infants sleep an extra 16.6 minutes a night, even though the WHO and various worldwide health agencies all recommend exclusive breastfeeding for 6 months[2].

“Controlled crying inherently puts breastfeeding at risk, but it’s not considered as such because most people don’t have the awareness of how crucial those night feeds are, but others actually actively look to reduce nursing as a means to improve sleep.”

Why Should We Care?

Some people would question why we should care if people are targeting feeding in order to improve sleep, but there are good reasons we should be highly skeptical of any such approach.  First, let’s acknowledge that breastfeeding and bedsharing – breastsleeping – is the evolutionary norm for the humans species[3] which means that outside of anything else we understand, there is likely good reason.

“Independent of breastsleeping, breastfeeding itself has been linked with dramatic declines in SIDS rates, with one meta-analysis finding that exclusive breastfeeding was associated with a reduction in SIDS risk of 73%.”

Dr. James McKenna has proposed that this combination helps to reduce Sudden Infant Death Syndrome[4] through keeping infants from falling into deep sleep for extended periods from which they may not recover.  This is not without merit as one of the findings with SIDS is that infants are at high risk on the first day and week of daycare and this is thought to be due to the stress of the change which results in deeper sleep at naptime[5][6].

Independent of breastsleeping, breastfeeding itself has been linked with dramatic declines in SIDS rates, with one meta-analysis finding that exclusive breastfeeding was associated with a reduction in SIDS risk of 73% (with a confidence interval of 69% to 76%)[7].  Although overall SIDS risk is low, this is a rather dramatic effect, and practices that reduce this effectiveness should be treated with caution.

Then of course there is the personal reason: If a mother wants to breastfeed, she needs to know that sleep interventions, or even just our focus on sleep, is something that may hinder that for her.  We talk a lot about women making their own choices, but most women I know are unaware what the effect is of sleeping changes on breastfeeding.  As Dr. Helen Ball has demonstrated time and again, how families sleep and what expectations they have for sleep can have effects on breastfeeding success and duration or elements associated with these outcomes[8][9][10].  Thus a mother with a desire to breastfeed needs to be made aware of the relationship between breastfeeding and infant sleep and know that it’s not a “bad” thing, but rather a part of our evolutionary history.

Does Breastfeeding Impact Sleep?

The short answer: yes.  Or rather, they are related, but not always in the ways that you might expect.

We’ll start with the research that most people cite in favour of having to put an end to all this nursing if people are going to get some sleep: wakings.  There is evidence that mothers who breastfeed have babies who wake more frequently, on average, than those who do not breastfeed.  For example, one study from Australia found that breastfeeding infants were 66% more likely to wake at night than their peers and 72% more likely to struggle to sleep alone[11].  (Luckily these researchers didn’t blame breastfeeding but rather suggested that there must be an evolutionary reason we need to explore and that low breastfeeding rates in many Western nations are likely linked to sleep expectations for infants.)

“Studies by Dr. James McKenna and colleagues finding infants who sleep close to their mother at night are 2 to 3 times more likely to breastfeed than when separated from her.”

This link to night wakings shouldn’t be surprising given that infants’ stomachs are so tiny and breastmilk is so readily absorbed that they get hungry and thus nurse more[12].  Sleeping closer to the infant also promotes breastfeeding with studies by Dr. James McKenna and colleagues finding infants who sleep close to their mother at night are 2 to 3 times more likely to breastfeed than when separated from her[13][14].  This is relevant to the discussion at hand insofar as most behavioural interventions require separation of mother and child which we have empirically seen impacts breastfeeding.

One issue that often comes up is that the link between breastfeeding and night wakings is not just found in groups of infants, but toddlers as well[15].  Some suggest night weaning as a means to get more sleep at this age as well and of course there are more complex issues at hand for some families, but by and large we should always remember that toddlers are not grown-ups.  Nursing is not something that ends in infancy from an evolutionary perspective, but rather something that typically goes on for years.

What may be helpful to know is that the research on the links between breastfeeding and waking in older infants and toddlers is less clear.  One study found no impact of breastfeeding on waking in a sample of 6- to 12-month old infants[16], suggesting breastfeeding ceases to have an impact once solids are introduced and that infant wake (as most did) for many other reasons.  Another larger-scale study found that breastfeeding at 6 months did impact wakings at 12 months, by 2 and 3 years, there was no relationship[17], though as breastfeeding was not assessed at these later time points, it’s difficult to ascertain the exact effect.

Regardless, toddlers nursing at night should still be considered the evolutionary norm by which we compare other behaviours, including night weaning.  As far as I know there is little research on any impacts to earlier-than-desired full weaning with night weaning so I cannot make any claim as to how that may impact the breastfeeding relationship.

“Breast milk is one of the ways in which babies develop this rhythm as the mother’s body passes on hormones at the levels she has to help the baby learn the difference between night and day.”

Returning to infancy, although researchers have generally focused on this element of wakings, there are other ways in which breastfeeding impacts sleep, ways that actually facilitate sleep.  One way is simply in terms of how much sleep infants get early on.  One study found that breastfed babies at 3 months of age slept a total of 40-45 minutes longer (measured via actigraphy) than formula-fed babies and parents of breastfed babies reported fewer sleep troubles[18].  This coincides with other research finding breastfeeding mothers, especially those who bedshare, report better sleep than their counterparts[19][20].

Another effect that is rarely mentioned to mothers is the transmission of certain hormones, notably melatonin and tryptophan, through breastmilk which not only helps babies fall asleep, but actually provides critical information about the circadian rhythm.  As babies are born with no real circadian rhythm, it is something that first emerges in the first few months of life, but then continues to develop over years[21].  However, research has found that breast milk is one of the ways in which babies develop this rhythm as the mother’s body passes on hormones at the levels she has to help the baby learn the difference between night and day[22].  Of course this is coupled with exposure to light which helps define this difference as well (and why formula fed babies do develop this rhythm), but the effects of these hormone levels in milk have a distinct benefit for mothers that is rarely discussed.

Notably, as baby develops his or her rhythm in conjunction with Mom (if no form of disconnect occurs) babies are more likely to share a circadian rhythm with their mother[23].  This means babies are more likely to not wake early if Mom is not a morning person, stay up too late if Mom is exhausted, and so on.  Now, of course, the relationship isn’t perfect and we all know those families where Mom may be breastfeeding on demand and not sleep training and still has a child with an opposite schedule to her own, but the likelihood is much less.  Given many mothers find the hardest part of sleep with little ones is to do with schedules that are opposed to their own, it would seem we should be prioritizing breastfeeding as a way to help cope with this.

Summary

We need, as a society, to stop trying to sacrifice breastfeeding for sleep.  This isn’t just to the sleep trainers and people peddling magic sleep solutions (yeah right), but to the researchers who continue to make limiting or structuring breastfeeding a piece of their sleep interventions.  Not only is this really not warranted in most situations, but may also lead to the perceived necessity of sleep training as the biological mechanisms in place to help our infants develop their sleep become compromised.

So for all you parents out there, nurse.  Nurse to sleep.  Nurse on demand.  Nurse often.  Nurse as long as you wish.  Do not let anyone tell you otherwise.

_______________________________

[1] St James-Roberts I, Sleep J, Morris S, Owen C, Gillham P.  Use of a behavioural programme in the first 3 months to prevent infant crying and sleeping problems.  J Paediatr Child Health 2001; 37: 289-297.

[2] Perkin MR, Bahnson HT, Logan K, Marrs T, Radulovic S, Craven J, Flohr C, Lack G.  Association of early introduction of solids with infant sleep: a secondary analysis of a randomized clinical trial.  JAMA Pediatr 2018; 172: e180739.

[3] McKenna JJ, Gettler LT.  There is no such thing as infant sleep, there is no such thing as breastfeeding, there is only breastsleeping.  Acta Paediatrica 2016; 105: 17-21.

[4] McKenna JJ, McDade T.  Why babies should never sleep alone: a review of the co-sleeping controversy in relation to SIDS, bedsharing and breast feeding.  Paediatric Respiratory Reviews 2005; 6: 134-152.

[5] Moon RY, Patel KM, Shaefer SJ.  Sudden infant death syndrome in child care settings.  Pediatrics 2000; 106: 295-300.

[6] De Jonge GA, Lanting CI, Brand R, Ruys JH, Semmekrot BA, Van Wouwe JP. Sudden infant death syndrome in child care settings in the Netherlands. Arch Dis Child 2004; 89: 427–30.

[7] Hauck FR, Thompson JMD, Tanabe KO, Moon RY, Vennemann MM.  Breastfeeding and reduced risk of sudden infant death syndrome: a meta-analysis.  Pediatrics 2011; 128: 103-110.

[8] Ball HL, Ward-Platt MP, Heslop E, Leech SJ, Brown KA.  Randomised trial of infant sleep location on the post-natal ward.  Arch Dis Child 2006; 91: 1005-1010.

[9] Ball HL.  Breastfeeding, bed-sharing, and infant sleep.  Birth 2003; 30: 181-188.

[10] Ball HL, Howel D, Bryant A, Best E, Russell C, Ward-Platt M.  Bed-sharing by breastfeeding mothers: who bed-shares and what is the relationship with breastfeeding duration?  Acta Paediatrica 2016; 105: 628-634

[11] Galbally M, Lewis AJ, McEgan K, Scalzo K, Amirul Islam FM.  Breastfeeding and infant sleep patterns: an Australian population study.  J Paediatr Ch Health 2013; 49: E147-E152.

[12] Ball HL.  Breastfeeding, bed-sharing, and infant sleep.  Birth 2003; 30: 181-188.

[13] McKenna JJ, Mosko SS, Richard CA.  Bedsharing promotes breastfeeding.  Pediatrics 1997; 100: 214-219.

[14] Gettler LT, McKenna JJ.  Evolutionary perspectives on mother-infant sleep proximity and breastfeeding in a laboratory setting.  Am J Phys Anthropol 2011; 144: 454-462.

[15] Weinraub M, Bender RH, Friedman SL, Susman EJ, Knoke B, et al. Patterns of developmental change in infants’ nighttime sleep awakenings from 6 through 36 months of age.  Developmental Psychology 2012; 48: 1511-28.

[16] Brown A, Harries V.  Infant sleep and night feeding patterns during later infancy: association with breastfeeding frequency, daytime complementary food intake, and infant weight.  Breastfeeding Medicine 2015; 10: https://doi.org/10.1089/bfm.2014.0153.

[17] Pennestri M, Laganiere C, Pokhvisneva I, Bouvette-Turcot A, Steiner M, Meany M, Gaudreau H.  Sleep patterns as a function of breastfeeding: from infancy to childhood.  Sleep 2018; 41 supp 1: A98.

[18] Doan T, Gardiner A, Gay CL, Lee KA.  Breast-feeding increases sleep duration of new parents.  J Perinat Neonat Nurs 2007; 21: 200-206.

[19] Rudzik AE, Ball HL.  Exploring maternal perceptions of infant sleep and feeding method among mothers in the United Kingdom: a qualitative focus group study.  Maternal and Child Health Journal 2016; 20: 33-40.

[20] Cong Z, Hale T, Kendall-Tackett K.  The effect of feeding method on sleep duration, maternal well being, and postpartum depression.  Clinical Lactation 2011; 2: 22-26.

[21] Brooks E, Canal MM.  Development of circadian rhythms: role of postnatal light environment.  Neuroscience & Biobehavioral Reviews 2013; 37: 551-560.

[22] Cubero J, Valero V, Sanchez J, Rivero M, Parvez H, Rodriguez AB, Barriga C.  The circadian rhythm of tryptophan in breast milk affects the rhythms of 6-sulfatoxymelatonin and sleep in newborns.  Neuroendocrinology Letters 2005; 26: 657-661.

[23] Thomas KA, Burr RL, Spieker S, Lee J, Chen J.  Mother-infant circadian rhythm: development of individual patterns and dyadic synchrony.  Early Human Development 2014; 90: 885-890.