Infant Bed-Sharing: Is Co-Sleeping With Babies Learned or Evolutionary Behavior?

In many cultures babies are not meant to sleep alone, and sleep is a social activity, where members of the extended family sleep in close proximity. Image by Bjwebbiz.

In many cultures, babies are not expected to sleep alone, and sleep is a social activity, where members of the extended family sleep in close proximity. Image by Bjwebbiz.

Should babies sleep alone, or with parents? It depends on who you ask, as the subject of parents sleeping with their babies (co-sleeping) remains controversial and emotionally charged.

Co-sleeping Safety: The Conflict

Western medical advice often promotes lone sleeping as the desirable norm on the grounds of safety. On the other hand, when anthropologists have studied parent-baby sleeping and feeding practices, they have come to very different conclusions: Bedsharing is prevalent in most non-Western industrialised societies, and carries enormous emotional and physiological benefits for the baby and mom.

Western European and US parents also practice bedsharing more than they think or like to admit.

Is It Good for Babies to Sleep Alone? Beliefs Differ Worldwide

Anthropologists have looked critically at a few Western assumptions, and compared them to other cultures. In America, for example, lone, uninterrupted sleep  (upwards of 4 hours) is a realistic and desirable outcome for even very young babies. Parents in the U.S. also believe that it is healthy and normal for a young baby or child to sleep alone as it promotes independence, and that co-sleeping, bedsharing and maternal contact fosters clinginess and holds back independence.

When researchers Morelli and McKenna looked at the comparison of sleeping practices  between United States, Guatemalan Mayan and Kipsigis babies in rural Kenya, however, it became apparent that not only is the practice of babies sleeping alone the perceived norm only in the U.S.A., non-US parents actually consider leaving babies alone to sleep an aberration.

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In the same way that US parents expressed a moral bias in favour of their babies getting used to sleeping alone as soon as possible, Mayan parents emphasized the need for their offspring to be next to his or her parents, and  a strong  disapproval of American  practices.  What’s more, amongst the Mayan portion of the study, it was customary  to co-sleep at any age, and lone sleeping was seen as unusual and unfortunate for anybody – babies share mother’s bed until around 2 years old, or until the next sibling comes along, and then they cosleep with another family member, usually the father. Guatemala Mayan parents considered their babies too young and vulnerable to be ‘independent’, so this was not a priority.

In Japan, studies have found that it is not uncommon for children to sleep adjacent to their mothers as infants and then carry on cosleeping with another family member until around the age of 15.  Here, parents consider newborn infants and young children as individuals who need to be made part of and dependent on the wider whole of society; it is not desirable for a young child to develop a strong separate identity.

Baby-Rearing and Co-Sleeping Customs Around the World


The Western norm is to put baby in a crib, but other societies see this as odd behavior. Image by fviggiani.

In the U.S., parents tend to believe that babies are born weak and dependent and need to develop as separate, independent individuals as soon and as quickly as possible.

Parents in other industrialised countries present more ambivalence, often bedsharing and cosleeping with their babies in practice – but not admitting to it, or not realising that they are. For example, babies may start the night in their cot and end up in the parental bed.

In addition, there are differences amongst different ethnic groups, so that bedsharing is more common in African American and Latin communities in the U.S., in the Maori in New Zealand, and in the Sami in Norway, as compared to the white, European-descended population. In the U.S., rural Appalachian communities do practice and embrace bed-sharing.

Co-Sleeping: Nature or Nurture?

Judging from anthropological studies of where and how much family bed-sharing is practised, it would appear that bedsharing and cosleeping has indeed been the human, and even non-human, norm across time and space.

Evolutionary anthropologists have linked cosleeping to survival, and contend that it must have been safer to sleep in groups, and to sleep lightly, for hominids and early humans, once they left their arboreal dwellings and started to live on the ground. Detailed lab studies examining cosleeping, breastfeeding,  and breathing mechanisms in bedsharing mothers and babies have found a significant complex relationship between the three, what McKenna et al term ‘sleep architecture.’

Click to Read Page Two: Anthropological Benefits of Co-Sleeping

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  1. Sue Kristoff says:

    Interesting. My first thought (before reading the article) on how co-sleeping began to be shunned was that “rich” people hired people to care for their children, so it was a sign of prosperity if you didn’t have your children in your bed.

    I partially co-slept because I didn’t have to fully wake up to feed my son during the night this way. I was working full time, so I treasured as much full sleep as I could get!

  2. Darla Dollman says:

    Shared my bed with both my babies and they survived just fine and are thriving in their 30s.

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