Co-Sleeping: Monkeys Do It, Apes Do It; Should We Do it Too?
To most of us, it’s a behavior that comes as naturally as breathing: When it’s a baby’s bedtime, we put carry her to her room, give her a kiss, and turn on the infant monitor. Through the evening we’ll check on her, and tiptoe around hoping that she sleeps through the night. When she does sleep on her own a goodly number of hours, we broadcast the good news with friends and family- she’s on the way towards independence!
But wait a minute. Why should we expect our littlest ones to sleep in isolation? Backing off from our cultural norms, doesn’t it seem a little strange?
After all, look at what other primates do. Lemurs of Madagascar, squirrel monkeys of Brazil, baboons and chimpanzees of Tanzania- in all these species, indeed in almost all nonhuman primate species, babies cling round-the-clock to mom, breast-feeding and sleeping at will. This intense day-and-night closeness lasts for months and sometimes years.
And mom-baby co-sleeping is not limited to our nonhuman kin. Some form of co-sleeping (bed-sharing or baby in a crib near the mom) is practiced broadly around the world. When in North American, European or Australian culture we bed down our child on her own, we diverge not only from millions of years of evolution but also from robust cross-cultural patterns.
Thanks to the work of biological anthropologist James McKenna and colleagues, the evolutionary perspective on co-sleeping is well known within science circles. I’m not blogging on this topic because it’s breaking science news, but instead because it’s a fabulous example of how an evolutionary perspective can help us think hard about our behavioral choices today.
In 2005, McKenna and Thomas McDade published a peer reviewed article called “Why babies should never sleep alone” in the journal Paediatric Respiratory Reviews (No. 6, 134-152-- email me if you’d like a copy). The pair explains that baby primates are not meant to be isolated, and when they are, their lungs are likely to shriek out a protest:
The emotional responses by infants and children
to resist parental isolation by crying and protesting are
probably innate and adaptive, since separation from the
caregiver most certainly meant rapid death for infants and
children in the environments within which childhood sleep
and emotions evolved.
Co-sleeping, McKenna and McDade note, isn’t an automatic good. When alcohol is consumed, or illegal drugs used, even when the mother smokes cigarettes, bed-sharing may be unsafe for the baby.
Yet when done responsibly, the benefits may be large. Human babies’ central nervous systems—including their brains and breathing systems-- are unfinished at birth. Women can birth a large-brained baby only because the baby’s brain grows especially intensively for a year outside the womb. Because of the neurological immaturity so evident right at birth, infants are at risk for Sudden Infant Death Syndrome (SIDS). Co-sleeping may reduce that risk because episodes of mutual arousal by mom and baby during the night help to regulate the baby’s breathing, and because in this context the baby sleeps supine, face up and ready for breastfeeding (and thus not in the most dangerous position, on its stomach).
McKenna and McDade conclude:
The general hypothesis that co-sleeping (at least in the
form of a committed caregiver’s proximity i.e,. roomsharing)
reduces SIDS among some SIDS prone infants is confirmed
by studies showing that roomsharing in the presence of an
active caregiver saves lives.
What an amazing public-health message! Happily, McKenna doesn’t write only for doctors and other academics. He’s taken his message on NBC’s Today Show, for example, and has written a popular book on co-sleeping called Sleeping with Your Baby: A Parent’s Guide to Co-sleeping.
Public outreach in anthropology is, I believe, incredibly important. But how effective is it? I’m curious to know: Have you in recent years read, or learned from radio or TV, about this evolutionary perspective on co-sleeping (starring monkeys and apes)? If so, what do you make of it?