Sleeping Babies Need Mom Beside Them

By Dr. James J. McKenna,
University of Notre Dame Mother-Baby Sleep Laboratory

Throughout human history, breast-feeding mothers sleeping alongside their infants constituted a marvelously adaptive system in which both the mothers' and infants' sleep physiology and health were connected in beneficial ways. By sleeping next to its mother, the infant receives protection, warmth, emotional reassurance, and breast milk - in just the forms and quantities that nature intended.

This sleeping arrangement permits mothers (and fathers) to respond quickly to the infant if it cries, chokes, or needs its nasal passages cleared, its body cooled, warmed, caressed, rocked or held. This arrangement thus helps to regulate the infant's breathing, sleep state, arousal patterns, heart rates and body temperature. The mother's proximity also stimulates the infant to feed more frequently, thus receiving more antibodies to fight disease. The increased nipple contact also causes changes in the mother's hormone levels that help to prevent a new pregnancy before the infant is ready to be weaned. In this way, the infant regulates its mother's biology, too; increased breast-feeding blocks ovulation, which helps to ensure that pregnancies will not ordinarily occur until the mother's body is able to restore the fat and iron reserves needed for optimal maternal health.

It is a curious fact that in Western societies the practice of mothers, fathers and infants sleeping together came to be thought of as strange, unhealthy and dangerous. Western parents are taught that "co-sleeping" will make the infant too dependent on them, or risk accidental suffocation. Such views are not supported by human experience worldwide, however, where for perhaps millions of years, infants as a matter of course slept next to at least one caregiver, usually the mother, in order to survive. At some point in recent history, infant separateness with low parental contact during the night came to be advocated by child care specialists, while infant-parent interdependence with high parental contact came to be discouraged. In fact, the few psychological studies which are available suggest that children who have "co-slept" in a loving and safe environment become better adjusted adults than those who were encouraged to sleep without parental contact or reassurance.

The fear of suffocating infants has a long and complex cultural history. Since before the middle ages "overlying" or suffocating infants deliberately was common, particularly among the poor in crowded cities. This form of infanticide led local church authorities to make laws forbidding parents to let infants sleep next to them. The practice of giving infants alcohol or opiates to get them to sleep also became common; under such conditions, babies often did not wake up, and it was presumed that the mothers must have overlaid them. Also, in smoke-filled, under-ventilated rooms, infants can easily succumb to asphyxia. Unfortunately, health officials in some Western countries promote the message that sleep contact between the mother and infant increases the chances of the infant dying from sudden infant death syndrome (SIDS). But the research on which this message is based only indicates that bed-sharing can be dangerous when it occurs in the context of extreme poverty or when the mother is a smoker. Some researchers have attempted to export this message to other cultures. However, in Japan, for example, where co-sleeping is the norm, SIDS rates are among the lowest in the world, which suggests that this arrangement may actually help to prevent SIDS.

Human infants need constant attention and contact with other human beings because they are unable to look after themselves. Unlike other mammals, they cannot keep themselves warm, move about, or feed themselves until relatively late in life. It is their extreme neurological immaturity at birth and slow maturation that make the mother-infant relationship so important. The human infant's brain is only about 25% of its adult weight at birth, whereas most other mammals are born with 60-90% of their adult brain size. The young of most other mammals become independent of their parents within a year, whereas humans take 14 to 17 years to become fully developed physically, and usually longer than that to be fully independent.

Apart from being a natural characteristic of our species, constant proximity to the mother during infancy is also made necessary by the need to feed frequently. Human milk is composed of relatively low amounts of protein and fat, and high amounts of quickly absorbed and metabolized sugars. Therefore the infant's hunger cycle is short, as is the time spent in deep sleep. All of these factors seem to indicate that the custom of separating infants from their parents during sleep time is more the result of cultural history than of fundamental physiological or psychological needs. Sleep laboratory studies have shown that bed-sharing, instead of sleeping in separate rooms, almost doubled the number of breast-feeding episodes and tripled the total nightly duration of breast-feeding. Infants cried much less frequently when sleeping next to their mothers, and spent less time awake. We think that the more frequently infants are breast-fed, the less likely they are to die from cot death.

Our scientific studies of mother and infants sleeping together have shown how tightly bound together the physiological and social aspects of the mother-infant relationship really are. Other studies have shown that separation of the mother and infant has adverse consequences. Anthropological considerations also suggest that separation between the mother and infant should be minimal. Western societies must consider carefully how far and under what circumstances they want to push infants away from the loving and protective co-sleeping environment. Infants' nutritional, emotional and social needs as well as maternal responses to them have evolved in this environment for millennia.

Dr. James J. McKenna is a Professor of Anthropology and the Director of the Center for Behavioral Studies of Mother-Infant Sleep, Notre Dame University. This article first appeared in the March-April 1996 issue of "World Health", the journal of the World Health Organization.


  1. Are you advocating that we sleep in Japanese or eastern style beds rather than the style of adult bed commonly seen in the United States?

  2. There are many ways to share sleep - i.e. sleep nearby your little one. This can be safely done on firm mattresses placed on the floor (our particular choice in our home). It can also be done by using a side-sleeper, a toddler bed next to parent's bed, a crib that has one side down and is made into a side-sleeper, etc. The Eastern style beds are surely more conducive to sharing sleep! But there are many ways to become creative and keep our babies nearby while they are little and benefit from doing so. :)

  3. We've been sleeping on a mattress on the floor for so many years I can't remember the last time I had a bed frame set up, lol!!! sometimes it's just a queen, sometimes a queen with a twin next to it, for a while it was two doubles side by side. Right now we just bought a king size.... but I'm prepared to pull the spare twin into our room too... seeing as lately we seem to end up with all the kids in bed with us by morning!!!! and I wouldn't have it any other way!!

  4. Love all the info on co-sleeping. We have a family bed in our house and every time I get into bed with my little ones I am certain that this is how God intended for us to sleep. It can be kind of lonely though so it is really good to find a community of other moms and dads doing the same thing! Keep it up!!! I for one am very grateful.

  5. I don't know about that "...increased nipple contact also causes changes in the mother's hormone levels that help to prevent a new pregnancy before the infant is ready to be weaned..." business, though. I'm tandem nursing on demand (bedsharing, too) & this is my fourth pregnancy in 4 years. I still harumph when I don't get that benefit of amenorrhea for more than a few months after birth. hmph!

    Aside from that, I adore bedsharing and can't imagine my kids not sleeping between us (well, maybe a few nights I could, but overall I love it ;)

  6. Cosleeping/night nursing certainly serve hormonally to increase milk supply and keep it high (as well as to regulate oxytocin and decrease cortisol and other stress hormones). But I sure wouldn't 'trust' cosleeping/night nursing and the hormone effect it has to act as efficient birth control. Even while nursing on demand every 3-4 hours, babywearing during the day, and cosleeping at night, I've met maaaannny women who started menstruating within months of birth and many who became pregnant again much sooner than they planned thinking this situation was eliminating ovulation.

  7. Yeah co-sleeping and night nursing didn't keep us from having another. LOL... but then we weren't really trying to not have another. Still they say that every lactating woman is different just like every pregnancy is different. And I have found that every child breastfeeding is a little different. What is birth control for one... may not be for another.

  8. :) I always say 100 years ago I'd be that one mom with 9 kids in 10 years. Exclusive breastfeeding/co-sleeping/all night nursing didn't prevent me from starting my cycle 6 weeks post-partum after both my girls! And every month after, like clockwork.

  9. Great article, thanks for posting!

  10. I love this, especially all the photos at the end. Priceless!

  11. I love articles like this so I can share with my friends on fb. My dd is 21 months old and I still haven't ovulated - not counting on it as birth control but it certainly seems to work for me:) My bed is also already warmed up by the time I get into it!!

  12. It sounds like it's not as common as thought. I am envious of those mamas who don't have their periods for months or even years while bfing.

    My dh & I are also older (I'll be 40 when this new one arrives :O ) So, everyone keeps telling us how hard it will be to get pg. It took us 3mo the first time, surprise the 2nd, 6w the 3rd & 1 cycle this time. All the while, I'm tandem nursing, cosleeping, babywearing, all that good granola mama stuff. lol.

    Just goes to show you that the babies know when they'll have it good & can't wait to join us attached parents ;)

  13. I read that research found that, in the UK, 85% of parents co-sleep with their children, but few intend to or admit to it openly! LOL! (sorry, no source handy).

    Wouldn't it be nice for those parents if it was accepted rather than frowned upon. Then they could feel guiltless (indeed that they were doing something good) and have enough prepared bed space rather than overhanging the side of the bed!

  14. We co slept from birth. When and how do we get him out of our bed?

    1. Gradually, and in his perfect timing. No child goes to high school wanting to sleep by mom. ;)



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