New moms are often overcome with the stress of losing sleep with their new babies. But one potential stress-reliever is good for your baby, too.

A study of 50 mothers and their babies from Douglas Hospital Research Centre in Montreal found that mothers who breast-feed are less stressed than those who bottle-feed their children.

Researcher Claire-Dominique Walker said it’s well established that breast milk is the best source of nutrition for infants.

“Our work now shows that there is a reciprocal benefit of breast-feeding to the mothers - they react less to stressful situations,” Walker said in a news release.

“This means they will focus more on their children and have more energy for activities such as attending to their infants and producing milk. This is an obvious gain for the children.”

Researchers studied the stress responses of 25 breast-feeding and 25 bottle-feeding mothers, having either one baby or several other children. The moms were exposed to different types of stressful situations, ranging from watching a video about hurt and lost children, to watching videos about public speaking and math problems. Stress was determined by measuring the levels of the stress hormone cortisol in their saliva.

“Our study may also have implications for women prone to postpartum depression,” Walker said. “Postpartum stress is a risk factor for postpartum depression. If we can better understand how the breast-feeding moms reduce their stress, by filtering daily life challenges, we may be able to better treat the moms prone to postpartum depression.”