|Throughout human history, breast-feeding mothers sleeping
alongside their infants constituted a marvelously adaptive system in which both the
mothers' and infants' sleep physiology and health were connected in beneficial ways.
By sleeping next to its mother, the infant receives protection, warmth, emotional
reassurance, and breast milk - in just the forms and quantities that nature intended.
This sleeping arrangement permits mothers (and fathers) to respond quickly to the
infant if it cries, chokes, or needs its nasal passages cleared, its body cooled,
warmed, caressed, rocked or held. This arrangement thus helps to regulate the infant's
breathing, sleep state, arousal patterns, heart rates and body temperature. The
mother's proximity also stimulates the infant to feed more frequently, thus receiving
more antibodies to fight disease. The increased nipple contact also causes changes in
the mother's hormone levels that help to prevent a new pregnancy before the infant is
ready to be weaned. In this way, the infant regulates its mother's biology, too;
increased breast-feeding blocks ovulation, which helps to ensure that pregnancies will
not ordinarily occur until the mother's body is able to restore the fat and iron
reserves needed for optimal maternal health.
It is a curious fact that in Western societies the practice of mothers, fathers and
infants sleeping together came to be thought of as strange, unhealthy and dangerous.
Western parents are taught that "co-sleeping" will make the infant too
dependent on them, or risk accidental suffocation. Such views are not supported by
human experience worldwide, however, where for perhaps millions of years, infants as a
matter of course slept next to at least one caregiver, usually the mother, in order to
survive. At some point in recent history, infant separateness with low parental
contact during the night came to be advocated by child care specialists, while
infant-parent interdependence with high parental contact came to be discouraged. In
fact, the few psychological studies which are available suggest that children who have
"co-slept" in a loving and safe environment become better adjusted adults
than those who were encouraged to sleep without parental contact or reassurance.
The fear of suffocating infants has a long and complex cultural history. Since
before the middle ages "overlying" or suffocating infants deliberately was
common, particularly among the poor in crowded cities. This form of infanticide led
local church authorities to make laws forbidding parents to let infants sleep next to
them. The practice of giving infants alcohol or opiates to get them to sleep also
became common; under such conditions, babies often did not wake up, and it was
presumed that the mothers must have overlaid them. Also, in smoke-filled,
under-ventilated rooms, infants can easily succumb to asphyxia. Unfortunately, health
officials in some Western countries promote the message that sleep contact between the
mother and infant increases the chances of the infant dying from sudden infant death
syndrome (SIDS). But the research on which this message is based only indicates that
bed-sharing can be dangerous when it occurs in the context of extreme poverty or when
the mother is a smoker. Some researchers have attempted to export this message to
other cultures. However, in Japan, for example, where co-sleeping is the norm, SIDS
rates are among the lowest in the world, which suggests that this arrangement may
actually help to prevent SIDS.
Human infants need constant attention and contact with other human beings because
they are unable to look after themselves. Unlike other mammals, they cannot keep
themselves warm, move about, or feed themselves until relatively late in life. It is
their extreme neurological immaturity at birth and slow maturation that make the
mother-infant relationship so important. The human infant's brain is only about 25% of
its adult weight at birth, whereas most other mammals are born with 60-90% of their
adult brain size. The young of most other mammals become independent of their parents
within a year, whereas humans take 14 to 17 years to become fully developed
physically, and usually longer than that to be fully independent.
Apart from being a natural characteristic of our species, constant proximity to the
mother during infancy is also made necessary by the need to feed frequently. Human
milk is composed of relatively low amounts of protein and fat, and high amounts of
quickly absorbed and metabolized sugars. Therefore the infant's hunger cycle is short,
as is the time spent in deep sleep. All of these factors seem to indicate that the
custom of separating infants from their parents during sleep time is more the result
of cultural history than of fundamental physiological or psychological needs. Sleep
laboratory studies have shown that bed-sharing, instead of sleeping in separate rooms,
almost doubled the number of breast-feeding episodes and tripled the total nightly
duration of breast-feeding. Infants cried much less frequently when sleeping next to
their mothers, and spent less time awake. We think that the more frequently infants
are breast-fed, the less likely they are to die from cot death.
Our scientific studies of mother and infants sleeping together have shown how
tightly bound together the physiological and social aspects of the mother-infant
relationship really are. Other studies have shown that separation of the mother and
infant has adverse consequences. Anthropological considerations also suggest that
separation between the mother and infant should be minimal. Western societies must
consider carefully how far and under what circumstances they want to push infants away
from the loving and protective co-sleeping environment. Infants' nutritional,
emotional and social needs as well as maternal responses to them have evolved in this
environment for millennia.