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Why We Never Ask
"Is it Safe for Infants to Sleep Alone?" Historical Origins of Scientific Bias
in the Bed-sharing SIDS "Debate"

"Bad science sets out to make a point, looks neither to the left nor to the right but only straight ahead for evidence that supports the point it sets out to make. When it finds evidence it likes, it gathers it tenderly and subjects it to little or no testing." - Mark Vonnegut, The Boston Globe, 10/24/99

"Don't sleep with your baby or put the baby down to sleep in an adult bed. The only safe place for babies to sleep is a crib that meets current safety standards and has a tight-fitting mattress." - Ann Brown, Commissioner, Consumer Product Safety Commission United States of America, 9/29/99

The "debate" about where infants should sleep and which hazards associated with different sleep environments are worth solving has never taken place on a level social or scientific playing field. Moral beliefs about how and where infants and children should sleep in western cultures are both tied to, and reflected in, the methods and conditions used to study infant sleep. Data collected on solitary, bottle-fed infants currently serves as the "gold standard" in research methodology, despite the fact that both breast­feeding and forms of co-sleeping are reaching historic highs. Thus, the pediatric sleep research community increasingly finds itself at odds with the behavior of the families it attempts to serve. This incongruity illustrates how tenacious traditional social/medical values and conventional understandings of infant sleep have become and why contemporary families feel so confused, frustrated, and unsupported.1-3

Inflammatory rhetoric, value judgments, mistaken presumptions, and reliance on anecdotal data play a major role in assisting anti-bed-sharing/co-sleeping researchers to promote their views.4-7 For example, the well-established distinctions between bed-sharing and dangerous couch sleeping have been ignored and used to inflate "bed-sharing" death statistics. Research findings also fail to account for the difference between the practice of bed-sharing and modifiable factors, which may be associated with bed-sharing. Such conclusions move from evidence-based science to social ideology, making value-based judgments about what "problems" are worth solving and which are not.

In this commentary, I call attention to the cultural and historical origins of western moral beliefs about how infants should sleep, and the scientific practices that continue to define what constitutes healthy and desirable infant sleep. I also review our cultural history and propose an explanation as to how and why anti-bed-sharing researchers have used poor quality data to generate sweeping public health recommendations. This knowledge is critical if we are to move beyond the erroneous assumption that mother-infant co-sleeping is pathological rather than overwhelmingly adaptive and deserves to be supported for those parents who practice it.

Critics of co-sleeping in the form of bed-sharing declare, "cribs are designed for babies while adult beds are not," and to a certain extent this is true. But since pediatric models of infant health, disease and illness are necessarily derived from human biology, it is appropriate to remember that the only true "baby-designed" sleep object or environment, is the mother's body. This fact, however, cannot serve as an analytic endpoint for understanding safe sleeping environments for infants. Specific environmental factors including dangerous furniture, bedding practices, and drug-desensitized parental bodies can transform an otherwise adaptive sleeping arrangement into a risky or dangerous one. To assume a priori that the normal, sober, attentive sleeping body of a human mother represents a risk to her infant, reveals an appalling lack of understanding of how natural selection shaped maternal sleep physiology in relationship to infant needs and vulnerabilities. Such a view irresponsibly disregards peer-reviewed scientific research showing unequivocally the human mother's ability to respond to her infant's needs while sleeping, even in the deepest stages of sleep.8-13

A scientifically appropriate beginning point for studies of safe sleeping arrangements must include the mother by the infant's side, co-sleeping. This fact is ignored, dismissed, or otherwise rejected by many physicians and western sleep and SIDS scientists. Ignorance of the biological significance of mother-infant co-sleeping with nighttime breast­feeding should no longer be tolerated by health professionals, scientists, or parents.

How Cultural Folk Assumptions About Infant Sleep Achieved Scientific Validation

The cultural reasons that explain the willingness of the pediatric/medical community to adopt invalid assumptions and use anecdotal data as a basis to recommend against all bed-sharing is easy to understand. Unfortunately, these same reasons make it difficult to successfully counteract anti-bed-sharing research and recent moves to use co-sleeping or bed-sharing as a reason to diagnose an infant's death as asphyxiation instead of SIDS. So entrenched are these assumptions and false stereotypes about co-sleeping that contemporary researchers and reviewers reading anti-bed-sharing reports are not likely to notice how and where the authors' cultural assumptions, preferences, and biased interpretations, are substituted for logically deducted scientific truths. These biases prevent researchers from acknowledging that the overwhelming number of deaths involve not co-sleeping, but infants sleeping alone.

For at least a century, western social and moral values have served as the basis for defining how and where infants should sleep. Specific concerns including protecting the husband/wife pair, and the perceived need to produce independent and secure infants through enforced nighttime separation, provided the initial basis for defining uninterrupted solitary infant sleep as "normal" and "healthy."8

The popularity of scheduled bottle-feeding in the 1950's reinforced the idea that uninterrupted solitary crib sleeping was "normal." In the late fifties and early sixties, when electro-physiological technology became widely available to measure and quantify infant sleep, breast­feeding was at an all-time low in the USA (less than 9% initiation). Both cow's milk and/or formula were thought superior to human milk. Pioneering sleep researchers thus had no reason to question the appropriateness of quantifying infant sleep and arousal patterns under solitary sleeping conditions using bottle-fed infants with little or no parental contact or nighttime feedings.

The "science" of infant sleep thus became one and the same with the morals and folk beliefs of the original scientists who first justified the method of measuring infant sleep. The "science" of infant sleep (quantified measurements of sleep architecture and arousals over the infant's first year) and the values (numerical and moral) which clinically defined desirable infant sleep became mutually reinforcing and supportive. This meant that if parents and their pediatricians wanted to produce "normal and healthy" sleeping infants they needed to re-create the original environmental conditions under which "healthy" infant sleep was measured. "Healthy infant sleep" became synonymous with solitary sleep and vice-versa - i.e. culture and science were yet again inextricably bound.

How and where infants sleep was no longer considered a simple relational family issue, but a serious medical one, to be assessed and monitored by authoritative sleep experts who passed this information along to family pediatricians. Adherence by infants to quantified "scientific models" of healthy sleep (including dire warnings to avoid co-sleeping at all costs) could supposedly be used to predict lifelong childhood health and sleep hygiene. Infant health could be obtained just as long as mothers, in the words of Dr. Spock, "followed the directions that their doctor gave them."

This chain of events explains how the question of what constitutes a safe infant sleep environment has been turned on its head. Species-wide and biologically normal and protective infant sleep environments, and mother-infant co-sleeping with breast­feeding, are assumed to be inherently lethal, while solitary crib sleeping is assumed to be safe. The burden of proof concerning infant safety came to challenge defenders of mother-infant co-sleeping, through a Commissioner of Consumer Product Safely, who oversees deficient products and goods. She was encouraged by a very small cohort of anti-bed-sharing researchers to make what in any other cultural context would surety be hailed as one of the most extraordinarily outrageous statements of our times: "The only safe place for an infant to sleep is in a crib."9

In sum, socially-constructed folk assumptions - rather than deductive, empirically based science - answered the original questions: How do infants sleep, and how and under what conditions should infant sleep be measured. The history of infant sleep studies in western cultures illustrates how a belief in the moral value of uninterrupted solitary infant sleep remains sacred, despite scientific studies that seriously challenge its biological normalcy or assumed advantages.10-14 These beliefs about infant sleep continue to lead a small number of SIDS and bed-sharing researchers to believe, a priori, that any violation of this artificially validated principle (solitary crib sleeping) is sure to lead to social or physical harm. In this way, co-sleeping - and specifically bed-sharing - are seen as both medical and moral violations.

Thus, anti-bed-sharing descriptive reports by Carrol-Pankhursi and Mortimer and others are not difficult to challenge on scientific grounds. The debate however, is not just about data, nor only about safety issues as is claimed by anti-bed-sharing researchers, but also about how - or if - to rethink traditional pediatric assumptions and values. Where data are missing they need only fall back on at least 100 years of anti-co-sleeping rhetoric and a general societal ignorance about the healthfulness of co-sleeping. Such ignorance is sustained by mutually reinforcing moral, social and scientific processes, all of which, in the field of sleep medicine, are practically one and the same.

See also Why babies should never sleep alone (PDF)

  1. Hoffman, J. "Sleep like a baby: what does that really mean?" Today's Parent 1999; 16 (7): 34-40
  2. Wright. R. "Why Johnny can't sleep." Time. April 14,1997.
  3. Nix, Shann "Confessions of a Bed Lizard." Mothering Magazine 2000; No 98:48-50.
  4. Carroll-Pankhurst C, Mortimer A. "Sudden infant death syndrome, bed-sharing, parental weight, and age at death." Pediatrics 2001; 107(3):530-536.
  5. Drago DA, Dannenberg AL "Infant mechanical suffocation deaths in the United States, 1980-1997." Pediatrics. 1999; 103: 5:e59.
  6. Nakamura S. Wind M. Danello M.D. "Review of hazards associated with children placed in adult beds." Arch Pediat Adoles Med. 1999; 153:1018-1023.
  7. Kemp J. Unger B. Wilkins N. Psara R. Udbetler TL. ADJ. Graham MA. Cose A. Thach B. "Unsafe sleep practices and an analysis of bed-sharing among infants dying suddenly and unexpectedly: Results of a four year population-based, death scene investigation of the sudden infant death syndrome and related deaths." Pediatrics 2001; 106:3. p e41
  8. McKenna J. "Cultural influences on infant sleep biology and the science that studies it: toward a more inclusive paradigm." In Sleep and Breathing in Children: A Developmental Approach (2000). Eds. Loughlin GM. Carroll JL. Marcus CL Marcel Dekker Inc: New York, 99-130.
  9. See "Co-Sleeping & Suffocation: A Response to the Consumer Product Safety Commission Study"
  10. Mosco S. Richard C. McKenna JJ. Drummond S. "Infant sleep architecture during bed-sharing with infant and possible implications for SIDS." Sleep 1996 19:677-684
  11. Mosco S. Richard C. and McKenna JJ. "Infant arousals during mother-infant bed-sharing; implications for infant sleep and SIDS research." Pediatrics. 1997; 100; 5: 841-849.
  12. Young J.Fleming PJ. "Reducing the risks of SIDS: The role of the pediatrician." Paediatrics Today. 1998; 6 (2):41-48.
  13. McKenna JJ. Mosko S. Dungy C. and McAnin C. "Sleep and arousal patterns of co-sleeping human mother/infant pairs: A preliminary physiological study with implications for the study of Sudden Infant Death Syndrome (SIDS)." Amer J Phys Anthrop 1990; 83:331-347.
  14. McKenna JJ. Mosko S. Richard C. "Bed-sharing promotes breast­feeding." Pediatrics. 1997; 100:214-219.

Dr. James J. McKenna is a Professor of Anthropology and the Director of the Mother-Baby Behavioral Sleep Laboratory, Notre Dame University. Reprinted with permission of the author.