In the study, published in the journal Child Development, researchers at Pennsylvania State University observed 45 families over the course of a week. The children ranged in age from 1 month to 2 years. Moms were asked questions about a variety of issues from how they were doing emotionally to the baby's sleep patterns.
Cameras were also installed to watch how the moms interacted with their babies in the middle of the night.
Here's what they found: Moms who had higher levels of symptoms of depression were more likely to respond to minor sounds, wake their baby up and nurse them (even if they weren't hungry) or pick their sleeping child up and put them in bed with them. It can be a vicious cycle.
"The more sleep you lose, the more likely you are to feel depressed," says lead author Douglas M. Teti, a professor of human development, psychology and pediatrics at Pennsylvania State University.
Image: Sleeping baby, via Shutterstock.