In the 1920s, the poet Federico García Lorca heard a woman in Granada sing a lullaby to her child and was struck by the acute sadness of the song. In a lecture delivered in Madrid in 1928, he observed that the country’s “saddest melodies and most melancholy texts” are contained in these so-called cradle songs. “Spain possesses joyous songs, jokes, jests … Why then has Spain reserved the most potent songs of blood to lull its children to sleep, those least suited to their delicate sensibilities?”

Lorca’s lecture, “On Lullabies,” focused specifically on lullabies in Spain, a country, in his words, of dead stones and soulful landscapes, “dashing its head against the walls.” But sad lullabies are hardly unique to that country.

Judging by lyrics alone, the lionshare of lullabies are not sweet and soothing; they are dark and creepy and macabre. There’s an Italian lullaby about a wolf devouring a lamb until “the skin and horns and nothing else remain.” An Andalusian lullaby about a rider who “led his horse to water but would not let him drink.” And a Turkish lullaby about a mother mourning her baby after an eagle has torn it to pieces, karmic punishment when the father fails to fulfill his vow of sacrificing three camels.

Here in America, there’s “Hush Little Baby” with its broken mirrors, fallen horses and mockingbirds that won’t sing. “Rock-a-Bye Baby” ends with an uncertain prognosis — death? injury? — after a cradle containing a baby plummets from a treetop. And, of course, “You are My Sunshine,” the saddest song ever.

So why are so many lullabies about death, despair and loss? And as it relates to their primary function — to lull the child to sleep — does it matter?

Music as Medicine

A lullaby, or cradle song, is defined by Merriam-Webster as just that: “a song to quiet children or lull them to sleep … a soothing refrain.” Any song can serve as a lullaby, says ethnomusicologist and UCLA lecturer Andrew Pettit, provided it is sufficiently slow and rhythmic. There are the songs that are composed specifically as lullabies, he says, and then there are “functional lullabies,” songs that are altered to serve that purpose.

People have said that lullabies are the space to sing the unsung, a place to say the unsayable. You’re alone. Nobody is listening, and you can express the feelings that are not okay to express in society.

“You can take any song, slow it down and sing it to your kid to help them sleep,” said Pettit, whose research has focused on lullabies from India. When his own daughter was an infant, for example, he sang the cowboy ballad “I Ride an Old Paint,” made famous by Woodie Guthrie and Pete Seeger.

Research has shown that lullabies, when used right, can soothe and possibly even help to heal an infant.

A study published in the journal Pediatrics in April 2013 found that live lullabies slowed infant heart rate, improved sucking behaviors that are critical for feeding, increased periods of “quiet alertness” and helped the babies sleep. Researchers followed 272 premature infants in 11 hospitals and found that the music, provided by a certified music therapist, offered stress relief for the parents too. The study concluded that “lullabies, sung live, can enhance bonding, thus decreasing the stress parents associate with premature infant care.”

Lullabies have also been studied as a form of pain relief. Dr. Mark Tramo, a UCLA neurologist and lecturer at the university’s Herb Alpert School of Music, performed a pilot study, also on preterm babies in the neonatal unit. He played lullabies to infants recovering from a painful heel stick procedure used to draw blood. His results suggested that music helped to slow the babies’ heart rates and thus reduce stress, but the study sample was too small to be definitive. He hopes to replicate the study in a larger population to learn more about the power of this effect.

“From a basic science standpoint, we want to know how music affects heart rate,” Tramo said. “But from a clinical standpoint, we want to know if music can prevent heart rate from going into the danger zone.”

As early as the 24th week of pregnancy, babies can hear a range of frequencies that include the human voice and most classical musical instruments, said Sally Goddard Blythe, director of the Institute for Neuro-Physiological Psychology and an expert in early child development. The mother’s voice “is particularly powerful because it resonates internally and externally, her body acting as the sounding board,” she wrote in her book, “The Genius of Natural Childhood.” “Both before and after birth, a mother’s voice provides a connection between respiration, sound and movement, an acoustic link from life and communication before birth – to the brave new world after birth.”

Explaining the Dark Lullaby

It is that voice and the rhythm and melody of the music that the youngest babies respond to, not the content of the song. Is it the case then, that the words are as much for the parent as for the child? That the mother is singing as much to herself as to the baby? Lyrics to lullabies, Pettit said, can indeed be interpreted as a reflection of the caregiver’s emotions.

There is a special physical bond between mother and child in the first year of life, in which mothers feel they can sing to their child about their own fears and anxieties, but in the safety and comfort of physical togetherness.

“People have said that lullabies are the space to sing the unsung,” Pettit said. “A place to say the unsayable. You’re alone. Nobody is listening, and you can express the feelings that are not okay to express in society.”

Driving this may be the closeness between the caregiver and child.

“There is a special physical bond between mother and child in the first year of life, in which mothers feel they can sing to their child about their own fears and anxieties, but in the safety and comfort of physical togetherness,” Blythe said.

In particular, lullabies embody a mother’s fear of loss, said Joanne Loewy, lead author of the April 2013 study in Pediatrics and director of the Louis Armstrong Center for Music and Medicine at Mount Sinai Beth Israel hospital in New York.

“This makes sense as the first infant/toddler years of life are fragile ones.” “Rock-a-Bye Baby”, for example, represents the common fear of crib death, Loewy said.

She compares it to breaking the glass at a Jewish wedding, a ritual that “portrays the sacredness of love that can easily be shattered, if not docked and cradled.”

In ancient Babylon, lullabies were used as magical charms, meant to protect sleeping babies. But darkness pervaded across cultures and centuries, with lullabies expressing fears directly or metaphorically about absent fathers, injured, sick or lost children, domestic abuse and unhappy lives. A gender divide was common in Indian folk lullabies, which celebrated boys, often predicting a wealthy and glorious future, while preparing girls for a life of hardship, Pettit said. But as the inequality gap between genders has narrowed in modern India, he added, recent lullabies have changed to reflect that.

In Spain in Lorca’s time, the most widespread group of cradle songs placed the child as “the sole actor in his own lullaby,” and in the lyrics, he was poor or his mother was missing or was not his mother. In response to such songs, children would cry, kick or protest, Lorca wrote.

“There is no… attempt to threaten, frighten or construct a scene,” Lorca said, “only to thrust the child into the song, alone and unarmed, a little knight defenseless against his mother’s reality.”

In an essay published in 1974, the late folk artist and researcher Bess Lomax Hawes had a similar observation about American lullabies. The most characteristic quality, she wrote, is the “spatial isolation” of the baby. In every traditional American lullaby, caregivers are somewhere else: hunting, for example, or out watching sheep or shaking dreamland trees.

“Baby, meanwhile, is up in a tree, or sailing off in a boat made out of the moon, or driving away with his ‘pretty little horses.’ When he does sleep, he is described as being in a place called ‘dreamland’ which, wherever it is, clearly isn’t his own bed; and he is variously requested or ordered to take himself to that ‘land of Nod’ by the linguistic convention that requires English speakers to ‘go to sleep.’”

The isolation of the child defines these lullabies, she wrote, suggesting that the line: “When the bough breaks, the cradle will fall,” is simply a reference to closing the bedroom door. The context is a culture that values independence and strength in its children. But the tradeoff is the separation strain experienced by the postpartum mother.

The American lullaby then, is a mother’s conversation with herself about separation, Hawes concluded: “And, as such, one of its most profoundly supportive functions is to make the inevitable and inexorable payment of our social dues just a little less personally painful.”

“I always found myself that rocking a baby to sleep was kind of a sad thing to do,” she wrote. “Not miserable or tragic or irksome — just a little bit sad, somehow.”

This post was updated to add a quote from Joanne Loewy, director of the Louis Armstrong Center for Music and Medicine.”

BONUS: Don’t miss this R-rated parody of a lullaby by comedian and composer Tim Minchin. Note: this one’s not for children.