For as far back as
you care to go, mothers have followed the protective and
convenient practice of sleeping. with their infants. Even now, for
the vast majority of people across the globe,
"co-sleeping" and nighttime breast-feeding remain
inseparable practices. Only in the past 200 years, and mostly in
Western industrialized societies, have parents considered it
normal and biologically appropriate for a mother and infant to
sleep apart.
In the sleep laboratory at the University of California's
Irvine School of Medicine, my colleagues and I observed
mother-infant pairs as they slept both apart and together over
three consecutive nights. Using a polygraph, we recorded the
mother's and infant's heart rates, brain waves (EEGs), breathing,
body temperature, and episodes of nursing. Infrared video
photography simultaneously monitored their behavior.
We found that bed-sharing infants face their mothers for most
of the night, and that mother and infant are highly responsive to
each other's movements, wake more frequently, and spend more time
in lighter stages of sleep than they do while sleeping alone.
Bed-sharing infants nurse almost twice as often, and three times
as long per bout, as they do when sleeping alone. But they rarely
cry. Mothers who routinely sleep with their infants get at least
as much sleep as mothers who sleep without them.
In addition to providing more nighttime nourishment and greater
protection, sleeping with the mother supplies the infant with a
steady stream of sensations of the mother's presence, including
touch, smell, movement, and warmth. These stimuli can perhaps even
compensate for the human infant's extreme neurological immaturity
at birth.
Co-sleeping might also turn out to give some babies protection
from sudden infant death syndrome (SIDS), a heartbreaking and
enigmatic killer. Co-sleeping infants nurse more often, sleep more
lightly, and have practice responding to maternal arousals.
Arousal deficiencies are suspected in some SIDS deaths, and long
periods in deep sleep may exacerbate this problem. Perhaps the
physiological changes induced by co-sleeping, especially when
combined with nighttime breastfeeding, can benefit some infants by
helping them sleep more lightly. At the same time, co-sleeping
makes it easier for a mother to detect and respond to an infant in
crisis. Rethinking another sleeping practice has already shown a
dramatic effect: in the United States, SIDS rates fell at least
30% after 1992, when the American Academy of Pediatrics
recommended placing sleeping babies on their backs, rather than
face down.
The effect of co-sleeping on SIDS remains to be proved, so it
would be premature to recommend it as the best arrangement for all
families. The possible hazards of co-sleeping must also be
assessed. Is the environment otherwise safe, with appropriate
bedding materials? Do the parents smoke? Do they use drugs or
alcohol? (These appear to be the main factors in those rare cases
in which a mother inadvertently smothers her child.) Since
co-sleeping was the ancestral condition, the future for our
infants may well entail a borrowing back from ancient ways.
