Every few months it seems there’s another headline proclaiming “Cry-It-Out Doesn’t Hurt Babies” or “The Dangers of Co-Sleeping.” Doctors warn parents that their child will “never” leave their bed once they let the child sleep there. One public health campaign even compared bed sharing with putting a baby to bed with a butcher knife. All of this can be very upsetting and confusing for parents.
Babies instinctually want to do the natural thing – sleep with someone – and protest when they are put down alone. But Western culture promotes the belief that infants and toddlers “should” sleep alone and frightens parents into thinking that they will harm their children (physically and psychologically) by sharing a bed with them.
Is there any evidence of this? In a word, no – as long as it is done safely and in a biologically normal way (see the Safe Sleep Seven). But really, is that even the right question?
Leading sleep researcher, Dr. James McKenna, explains that many infant sleep studies are backwards, looking at cultural beliefs instead of scientific paradigms. They start with the assumption that solitary infant sleep is normal (it’s not – see my last three posts). These studies usually ask “is co-sleeping/bedsharing safe?” or “does sleep training reduce infant waking and crying?” rather than “is it healthy and safe for babies to sleep alone?”
In fact, McKenna believes that not asking the correct question resulted in a vast cultural experiment that contributed to many babies dying of Sudden Infant Death Syndrome (SIDS). In years past, the untested cultural belief that babies should sleep alone led to doctors telling parents to put infants down on their tummies so they would stay asleep longer. This resulted in huge spikes in SIDS rates that have since fallen with “back to sleep” campaigns.
Artificial (formula) feeding, which made it easier for baby nurses and others to care for infants as night, has also emerged as a major SIDS risk factor. Even solitary sleeping is no longer recommended – a parent’s breathing and other factors help prevent SIDS by stimulating the immature infant respiratory system.
Biologically normal infant sleep components include breastfeeding, sleeping next to the mother and varied sleep positions including side and back. In traditional cultures, sharing sleep takes place on a firm surface, usually the floor (these cultures also have very low SIDS rates).
In Western societies, parents are told to keep infants in their rooms, but never in their beds. Yet, because babies are biologically programmed to seek human contact, warnings against bedsharing often lead to parents falling asleep with their infants on unsafe surfaces such as couches or recliners.
Infant sleeping on unsafe surfaces (which can also include hazards such as mattresses that don’t fit tightly in the frame) is often lumped together with other forms of co-sleeping and even bedsharing in many studies. Unsafe surfaces are also confused as a risk factor for SIDS, rather than for suffocation. But as McKenna and his colleague Lee Gettler note, “…(with) careful and complete examination of death scenes, the results revealed that 99% of bedsharing deaths could be explained by the presence of at least one and usually multiple independent risk factors…such as maternal smoking, prone infant sleep, use of alcohol and/or drugs by the bedsharing adults.”
The authors of Sweet Sleep researched this topic extensively and concluded that there is no greater risk of SIDS when infants under four months old bedshare safely (again, the Safe Sleep Seven) than when they sleep nearby in a crib. And why should there be? Sleep sharing is the biological norm for our species and evolution would have stopped it long ago if it wasn’t safe. Sweet Sleep also states that a baby over four months can safely bedshare with any responsible, sober, non-smoking adult.
In addition to sleeping alone, Western parents are told that infants should be trained to sleep through the night as early as possible. These methods all involve varying amounts of crying to sleep – something that is not biologically normal for our species.
The phenomenon of “extinction” sleep training (a holdover from the discredited psychological theory of behaviorism) is another vast social experiment currently being conducted without evidence that it is healthy and safe for babies. In fact, one study found a disturbing rise in the stress hormone cortisol in infants “crying it out” (chronically elevated cortisol can harm a baby’s developing brain). Even studies that claim the practice is harmless demonstrate no benefits for either parents or babies – and sleep training does shorten breastfeeding duration (again, a SIDS risk factor).
Of course, sometimes babies cry no matter how responsive we are as parents, but holding and comforting babies seems to mitigate the negative effects of this stress. Studies that have looked at social sleeping with one or more parents have found multiple benefits, including increased breastfeeding (more antibodies and other benefits for baby), more rest for both infants and parents and a stronger emotional bond.
In biologically normal sleep, infant and mother often stir without fully waking – baby latches on and both fall back asleep. The parent’s body helps babies wake frequently during the night so they don’t sleep too deeply and stop breathing.
Advocates of sleep training start with the Western cultural belief that solitary sleep is normal and babies should not disturb their parents at night. Infant night wakings are seen as problematic, rather than protective. Researchers test whether sleep training leads to less crying and fewer awakenings – NOT if this is good for babies.
Again we need to ask – is it healthy and safe for babies to sleep alone? Do parents have to teach their babies to fall asleep? Do parents get more rest if they wean from the breast and sleep train? Does it lead to happier, more independent children? Do sleep trained infants cry less? There is little evidence for any of this and some evidence of the opposite.
There is another way – a way that is normal for our species and has proven benefits, including more sleep for parents and babies. We don’t have to sleep on the ground in the woods, but we do need to avoid hazards associated with our comfortable Western lifestyles. We will look at this in the next What Babies Need.
McKenna, Ball, and Gettler. Mother–Infant Cosleeping, Breastfeeding and Sudden
Infant Death Syndrome: What Biological Anthropology Has Discovered About Normal Infant Sleep and Pediatric Sleep Medicine. Yearbook of Physical Anthropology, 2007
Middlemiss W, Granger DA, Goldberg WA, Nathans L. Asynchrony of mother-infant hypothalamic-pituitary-adrenal axis activity following extinction of infant crying responses induced during the transition to sleep. Early Human Development. 2012
McKenna & Gettler. Co-Sleeping, Breastfeeding and Sudden Infant Death Syndrome. Encyclopedia on Early Childhood Development. 2010 (online)
Narvaez, D. The Ethics of Early Life Care: The Harms of Sleep Training, Clinical Lactation, 2013
Kendall-Tacket, K.A., Cong, Z., & Hale, T.W. Mother-infant sleep location and nighttime feeding behavior: U.S. data from the Survey of Mothers’ Sleep and Fatigue. Clinical Lactation. 2010
Bartick, M. and Smith, L.J. Speaking Out on Safe Sleep: Evidence-Based Infant Sleep Recommendations. Breastfeeding Medicine. 2014
Whittingham, K. and Douglas, P. Optimizing Parent–Infant Sleep From Birth To 6 Months: A New Paradigm. Infant Ment. Health J., 2014
Middlemiss & Kendall-Tackett, The Science of Mother-Infant Sleep. 2013
McKenna, J. (2007) Sleeping with Your Baby: A Parent’s Guide to Cosleeping.
Pitman, T., Smith, L., West, D., Wiessinger, D. (2014) Sweet Sleep: Nighttime and Naptime Strategies for the Breastfeeding Family. La Leche League International.
News report featuring Dr. McKenna: https://www.youtube.com/watch?v=e3YXRf59TGs