Babies feel the rhythm: New study finds infants sync with moms during lullabies

Elvis once said, “Rhythm is something you either have or don't have." But where does it come from?

A new study suggests that Elvis and everyone with rhythm may have gotten it from their moms.

The experience of singing to a baby is universal, across languages, cultures and time -- especially well-loved lullabies. Canadian researchers took a look at the relationship between mothers and babies during lullabies.

“We know lullabies work with babies,” Laura Cirelli, the primary author, said. But she wanted to know, “how our parents shape that experience.”

In this cross sectional study, 30 mothers were asked to sing “Twinkle, Twinkle, Little Star” to their children in two moods: “playful” and “soothing.”

For the study, moms sang to their babies up to 10 times. Baby brain arousal was measured via devices placed on the skin that are similar to a polygraph and measure sweat gland activity.

Cirelli explained that sweat is an indicator of mood because “when we are excited, levels increase” and “when we are calm, they decrease.”

Increased stress leads to increased sweat gland activity and higher skin conductance levels. Calm states mean decreased sweat gland activity and decreased skin conductance.

The authors also monitored baby behavior during the singing.

During soothing versions of the song, moms sang more slowly and at a lower pitch, the researchers found. This was less arousing for both moms and babies and that decrease was “correlated," meaning that mom's and baby's response were synced.

During playful versions, moms sang more quickly and with a higher pitch; arousal levels for both were stable. Both infant attention to mom and babies’ overall happiness ratings -- determined by facial expression, such as smiling -- increased.

“Infant brains must be able to track auditory events to make sense of music,” the author said.

She suggests that early exposure to music may help babies develop rhythm perception which may facilitate engagement in both social and emotional settings. Cirelli says, “music is a tool that we can use to bring people together, and this starts in infancy.”

She suggested a playlist based on rhythmic qualities, saying that "lullabies may be used to soothe” and “play songs for entertainment and getting attention.”

Lullabies
“Twinkle Twinkle Little Star”
“You Are My Sunshine”
“Rock-a-bye-baby”
“Hush Little Baby”
“Somewhere Over the Rainbow”

Playful
“Itsy Bitsy Spider”
“The Wheels On the Bus”
“If You’re Happy and You Know It”
“Old MacDonald”
“Zoom Zoom Zoom”

The study is limited in some ways. The research was reported this week as part of a meeting presentation and hasn't been published at this time in a peer-reviewed academic journal. Additionally, this is a small study including only 30 pairs of moms and babies. The author plans to open a baby lab and continue researching this field.

Dr. Joseph Cafone is a fourth-year internal medicine and pediatrics resident working in the ABC News Medical Unit.