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

Anthropological Benefits of Co-Sleeping

Where babies are healthy, full term, there is no parental use of alcohol, drugs or tobacco, and breast feeding is practiced, routine bed-sharing produces amazing results.


Research has shown that mother and babies regulate their breathing in harmony and are easily awoken by any changes. Image by Karpati Gabor.

Babies and mothers essentially tune in and coordinate their breathing very subtly while they sleep, so that the mother’s breathing helps the infant to regulate theirs in case of sleep apnea (inability to continue the breathing reflex) and/or irregularities due to their immature respiratory systems.

Failure to regulate these reflexes could otherwise lead to SIDS.

Babies and mothers sleep more lightly and wake up more frequently, which increases parental monitoring of the baby, but also enables the baby to arouse more easily if they are experiencing any difficulties with their breathing. Light sleeping is therefore a blessing in disguise.

In addition, babies who bed-share and breast feed are usually placed on their backs or sides and almost always end up settling facing mum, at breast-height.  They are therefore extremely unlikely to roll to the prone position (on their front), and being prone has been identified as a significant  risk in SIDS. In addition, breastfeeding increases in co-sleeping situations.

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Scientific Evidence and Social Change

So if both nature and nurture seem to have encouraged us to sleep very close to our infant offspring from the dawn of time, why and how did lone sleeping become the promoted ‘norm’ in modern industrial and post industrial societies? Undestandably, the perceived link with SIDS remains a factor. But the most important reasons are cultural and social.

McKenna mentions several factors, particularly from 18th century and the onset of industrialization, all the way through to the 1960s, 1970sand beyond.

In the 1700s, the Catholic Church attempted to stop infanticide among poor, starving mothers who confessed to ‘overlaying their babies’ due to lack of birth control and  the means to support a family. This led priests to ‘ban’ infants from parental beds.

Also the industrial revolution brought new social ideals: A growing cultural emphasis on individualism, autonomy, competition. This led to fear of ‘spoiling’ children with excessive affection, fear of children being exposed to the sexual acts of the parents (emphasised by Freudian theories about sexuality and psychosis) a growing deference to figures of external authority (scientists, doctors, experts) and a belief in the superiority of technology over ‘primitive’ practices. This also led to the custom of discouraging breastfeeding in favour of bottle feeding.

We Are All The ‘Norm’

There are clearly tensions for many 21st century women in post-industrial Western societies, particularly from more affluent social backgrounds, between the different aspects of parenting. How does a mom achieve emotionally nurturing, enjoyable and safe parenting, successful breastfeeding and simply getting a ‘full night sleep’?

Human behaviour is distinguished by the perennial fusion of nature and nurture, and close analysis often defies assumptions  that scientific evidence and its models are always neutral and devoid of cultural bias.

Sources and Further Reading

R Carpenter, C. Mc Garvey, E.A. Mitchell et al. Bed sharing when parents do not smoke: is there a risk of SIDS?  (2013). BMJ Accessed October 13, 2013.

The Baby Friendly Initiative. Unicef UK Baby Friendly Initiative Statement on New Bed Sharing Research.(2013). Unicef UK . Accessed October 13, 2013.

G.Morelli, D.Oppenheim, B. Rogoff, D. Goldsmith. Cultural variations in Infants’ Sleeping Arrangements: Questions of Independence. (1992). Developmental Psychology: The American Psychological Association.

J McKenna, H. Ball, L.Gettler. Mother-Infant Cosleeping, Breastfeeding and Sudden Infant Death Syndrome: What Biological Anthropology Has Discovered About Normal Infant Sleep and Pediatric Sleep Medicine(2007). Yearbook of Physical Anthropology.

J. McKenna. Cultural Influences on Infant and Childhood Sleep Biology and the Science that Studies it. (2007). Sleeping and Breathing in Children, a Developmental Approach: Marcel Dekker.

Author’s Note: We are not arguing for or against co-sleeping, nor are we giving parents any advice on this delicate issue. Rather, we are looking more closely at anthropological analysis of bedsharing as a practice, and evaluating whether co-sleeping is a ‘natural’ or ‘learned’ behaviour.

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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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