Breast milk is well-known to contain antibodies and nutrients that play a vital role in a baby’s health. Babies fed with formula rather than breast milk generally have a higher risk for conditions such as asthma, diabetes and obesity.
However, moms who decide to breast-feed or co-sleep with their babies are impacting their own health, not just the health of their babies, according to a new study conducted at Northwestern University. The study found that women with the most ideal stress hormone patterns were those who breast-fed their babies but did not sleep in the same bed with them. Women who did the opposite — slept with their babies, but didn’t breast-feed them — had the worst stress hormone patterns. The news could be helpful to new moms looking for ways to reduce stress while providing optimal care for their newborns.
More Energy in the Day, Easier to Sleep at Night
During the study, researchers from Northwestern University’s School of Education and Social Policy examined the saliva samples of 195 women from Chicago. The saliva samples were taken over the course of one day roughly six months after the women gave birth, with a sample collected upon waking, 30 minutes later, and just before bedtime.
The researchers analyzed the saliva samples in order to determine the levels of cortisol, a stress hormone, in each woman. Ideally, cortisol levels should be highest in the morning, when alertness and energy are needed to tackle the day, and lower in the evening, when a heightened level of alertness could interfere with sleep.
The moms in the study who breast-fed and abstained from co-sleeping enjoyed the sharpest drops in cortisol levels between their morning saliva samples and the evening one. Previous studies have indicated that individuals with this trait are more likely to survive certain types of cancer, experience better cardiovascular health and be healthier in general.
The mothers in the study who neither breast-fed nor slept with their babies still experienced a decline in cortisol levels over the course of the day, but not to the same extent as mothers who breast-fed but didn’t co-sleep. Mom who co-slept with their babies but abstained from breast-feeding experienced the least-ideal cortisol patterns.
Cortisol, Breast-Feeding and Stress
In previous studies, researchers found that cortisol levels tended to steadily rise throughout pregnancy and fall off following birth. However, none of these older studies examined cortisol levels in mothers several months after childbirth, as was done in the Northwestern University study.
According to Clarissa Simon, one of the lead researchers behind the study, previous studies have also found that breast feeding relieves stress and depression. Simon suggests that moms who share a bed with their infants may have trouble sleeping, which could affect cortisol levels during the day.
The study was limited in that it only examined mothers from a single suburb of Chicago. The results could be further confirmed by a larger study that includes mothers from a more diverse set of locations.
The Bottom Line
A breast feeding mom who does not sleep with her baby experiences the most optimal stress hormone levels throughout the day, according to a new study by researchers in Chicago. The study, which has yet to receive publication, was presented recently at an annual meeting of the American Public Health Association.