Previous studies have found that breastfed babies have protective stages of healthy sleep/wake cycles - reducing the risk of SIDS and other breathing, hormonal, and bio-regulatory irregularities. It was previously thought that because breastfed babies spend more of their day and night in an alert state, that their mothers may have less sleep than formula fed babies' mothers.
Drs. Stephanie Quillin and Lee Glenn, who led the study at East Tennessee State, sought to address the unsolved question of whether there is an interaction between the type of feeding (breastfed or formula fed) and sleep arrangements (sharing sleep vs. solo sleeping) that impacts mothers' postpartum sleep.
Thrity-three first time mothers and their newborns participated in the study over the course of their fourth week postpartum. Total amount of sleep, amount of night-time sleep, number of wakings, and number of sleep periods in 24 hours were recorded using a modified version of the Barnard and Eyres sleep instrument.
Results showed that breastfed babies did have less total sleep per day than formula fed babies, but that nursing, cosleeping mothers enjoyed more sleep in each 24 hour period than those who fed by bottle or put baby to sleep solo. Breastfeeding mothers also slept significantly more often than other mothers when sharing sleep at night or during naps. Bottle feeding mothers' amount of sleep was not changed by the location of their baby, (which is not to suggest that infants didn't benefit from sleeping near their mothers, as we know hormones, respiration, and cardiovascular systems are significantly impacted when a baby is close to his mother during sleep vs. left solo and apart from her).
Average total sleep for a four week old baby was approximately 14 hours daily. Researchers concluded that mothers do in fact receive the most sleep postpartum when breastfeeding and sleeping next to their baby. They have suggested the need for increased and improved methods and means for breastfeeding mothers and their babies to share sleep in a safe manner.
As sociological, anthropological, and historical research has shown, the system of sharing sleep is not a novel one. Most mothers and their babies around the world today, and throughout human history, sleep near to each other during the early years of vulnerability and need for night time nourishment, comfort, security and regulation. Included in this sleep sharing paradigm are all other mammals whose babies sleep near mom during early development, and who, like humans, are defined as 'mammals' in part due to their need for mothers' milk.
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Nighttime Parenting: How to Get Your Baby and Child to Sleep
The Baby Sleep Book
Sleeping With Your Baby: A Parent's Guide to CoSleeping
The Family Bed: An Age Old Concept in Child Rearing