Parents sing lullabies to their children all across the world. For the littlest babies, though, lullabies and other musical sounds might do more than calm a baby's crying.
A recent study found that different types of music can actually have an effect on preemies' vital signs and feeding and breathing behaviors.
The babies heard lullabies, heartbeat sounds and breath sounds.
Positive changes in sucking behavior, eating, sleeping behaviors and heart rate occurred in the babies when they heard different music types.
The study, led by Joanne Loewy, DA, of the The Louis Armstrong Center for Music & Medicine at Beth Israel Medical Center in New York City, aimed to see how different types of music might influence vital signs in premature newborns.
The study involved 272 babies who were all born at 32 weeks of pregnancy or earlier. All the preemies had either respiratory distress syndrome, clinical sepsis (infection) and/or were born underweight for their age in pregnancy weeks.
Over a two-week period, each baby was exposed to either one of three different types of music or no music at all at six random times. No baby received the same type of music more than one day during a single week during the study.
One type of music was a lullaby identified by each baby's parents as culturally important to their family. If the parents did not have a lullaby to suggest, then "Twinkle Twinkle Little Star" was used because the melody is well known throughout different cultures in the US.
The parents were asked to sing the lullaby if they felt comfortable doing so. For the babies of parents who chose not to sing, the trained musical therapist who sang matched her voice to the vocal range of the mother so that the vocal range was familiar to the infant.
The second type of music was "entrained breathing sounds," conveyed with a musical instrument called the Remo ocean disc. The study describes this instrument as round and filled with tiny metal balls.
"When the disc is rotated, the metal balls move slowly to create a sound effect that is contained and quiet and meant to simulate the fluid sounds of the womb," the study describes. "The disc as it is played live can be entrained to match the infant’s inhalation and exhalation cycles."
The third type of music used a rectangular instrument called a gato box that could simulate the sound of a heartbeat, similar to what a baby would hear in the womb.
Each music type was played between 55 and 65 decibels and was played in morning or afternoon. Data on the baby's vital signs, feeding behaviors and sleeping patterns were gathered before, during and after each time the music was played.
This data was also gathered throughout the two-week period and in the opposite time of day as the music on the days that music was played.
If the music was played in the morning, data was gathered that afternoon also. If music was played in the afternoon, data was gathered that morning as well.
Then the researchers compared all their data to determine how the different music types affected the babies.
They found that changes in the babies' heart rates occurred with all three music types. The babies' heart rates slowed down during the lullaby, during the heartbeat sounds and after the ocean disc sounds.
The researchers also noted positive changes in the babies' sucking behavior during the heartbeat sounds and positive changes in their sleeping patterns during the ocean disc sounds.
The researchers reported the rate of "good sleep" as 94 percent during the lullaby, 96 percent during the ocean disc sounds and 95 percent during the heartbeat sounds.
During the lullabies, the babies also ate more and showed more sucking behavior. The parents also felt less stressed during the lullabies.
Overall, 52 percent of the babies heard "Twinkle Twinkle Little Star," and 48 percent heard a different culturally important song.
Babies who heard "Twinkle" showed slightly higher oxygen saturation levels than children hearing other songs. However, children hearing other songs showed slightly higher levels of calorie intake and feeding behaviors.
"The informed, intentional therapeutic use of live sound and parent-preferred lullabies applied by a certified music therapist can influence cardiac and respiratory function," the researchers concluded based on their analysis of the results.
"Entrained with a premature infant’s observed vital signs, sound and lullaby may improve feeding behaviors and sucking patterns and may increase prolonged periods of quiet–alert states," they continued.
"Parent-preferred lullabies, sung live, can enhance bonding, thus decreasing the stress parents associate with premature infant care," they wrote.
The study was published April 15 in the journal Pediatrics. The research was funded by the Heather on Earth Music Foundation. The authors declared no conflicts of interest.