The Neuroscience of "Rock-a-Bye Baby" and Rocking Adult Beds

Rhythmic nighttime rocking boosts deep sleep and memory via neural entrainment.

Posted Jan 26, 2019

PublicDomainPictures/Pixabay
Source: PublicDomainPictures/Pixabay

Parents intuitively use continuous rhythmic rocking motions to soothe babies and induce sleep. One could assume that humans have rocked their young to sleep since temps immémorial. Throughout recorded history, rocking has been a standard reference in nursery rhymes, lullabies, and pop music.

The first known published references to “rock-a-bye baby" date back hundreds of years. For example, the partial lyrics to this lullaby appeared in a 1765 print version of Mother Goose's Melody.

In 1893, the New York Times reported, “The composer of the popular song, “Rock-a-Bye Baby,” which beautifully adapts and incorporates the old and familiar lullaby, is Miss Effie L. Canning.” In 1918, a Broadway interpretation of this lullaby, "Rock-a-Bye Your Baby (with a Dixie Melody)," from the musical Sinbad was recorded by Al Jolson and reached #1 on the charts. Almost a century later, in 2016, Clean Bandit (feat. Sean Paul & Anne-Marie) hit the top of the charts with their 21st-century interpretation of Rockabye, which has been viewed by over two billion people on YouTube.

Have you ever wondered why rocking has the universal ability to calm a baby and helps infants fall asleep? A new study, “Whole-Night Continuous Rocking Entrains Spontaneous Neural Oscillations with Benefits for Sleep and Memory,” offers fresh clues about the neuroscience behind "Rock-a-Bye Baby" and reveals that—just like infants—adults also benefit from rhythmic mechanosensory stimulation (e.g., rocking) throughout the night. This paper (Perrault et al., 2019) was published January 24 in the journal Current Biology.

"Having a good night's sleep means falling asleep rapidly and then staying asleep during the whole night," the study’s senior author Laurence Bayer of the University of Geneva said in a statement. "Our volunteers—even if they were all good sleepers—fell asleep more rapidly when rocked and had longer periods of deeper sleep associated with fewer arousals during the night. We thus show that rocking is good for sleep."

This study is a follow-up to a 2011 paper, "Rocking Synchronizes Brain Waves During a Short Nap,” by Bayer et al. which reported that lying on a slowly rocking bed (0.25 Hz) during a nap helped study participants doze off more quickly and sleep more soundly. Curling up on a rocking bed during 45-minute afternoon napping sessions appeared to enhance synchronous brain wave activity within thalamo-cortical networks.

For their most recent study on the brain benefits of sleeping in a rocking bed, Bayer and his team set out to investigate how mechanically rocking someone all night long effects sleep. From a neuroscience perspective, their focus was on how whole-night continuous rocking influenced brain wave oscillations and subsequent memory consolidation.

Analysis of the research data showed that sleeping in a rocking bed with a gentle, side-to-side lateral movement helped study participants fall asleep more quickly. Participants in the rocking bed also spent more time in deep sleep and woke up less frequently compared to a control group that slept in a traditional bed of identical construction that did not rock back and forth. When given memory tests the following day, they performed better than study participants who hadn't been gently rocked. 

This video below shows the rocking bed recently used by Laurence Bayer and first author Aurore Perrault in their Sleep, Cognition and Neuroimaging Laboratory (SCNLab) in Switzerland.

The gentle and continuous rocking motion of the bed used by sleep researchers at the University of Geneva helped to synchronize neural activity between thalamo-cortical networks of the brain, which the researchers believe play an important role in boosting memory consolidation.

“Altogether, these findings demonstrate that a continuous rocking stimulation strengthens deep sleep via the neural entrainment of intrinsic sleep oscillations,” the authors concluded.

A companion study on the neuroscience of rocking and sleep was also published online January 24 in Current Biology. This paper (Kompotis et al., 2019) reports that gentle rocking promotes deep sleep in mice via the rhythmic stimulation of the vestibular system.

This study on mice was led by Paul Franken of the University of Lausanne in Switzerland along with first author Konstantinos Kompotis and colleagues. The goal of this research was to build on the aforementioned whole-night sleep study on young adults by identifying if rocking promotes sleep and brain wave changes in other species.

For this study, Kompotis et al. used mechanized equipment to gently rock mouse cages back and forth while mice were sleeping. The researchers used EEG and EMG electrodes to monitor brain wave activity while the mice slept. Just like young adults in the first experiment, the rocking mice fell asleep more quickly, spent more time in deep sleep, and had fewer wake episodes while sleeping.

As the authors explain, “Rocking has long been known to promote sleep in infants and, more recently, also in adults, (Perrault et al., 2019) increasing NREM sleep stage N2 and enhancing EEG slow waves and spindles. Our findings demonstrate that rocking also promotes sleep in the mouse and that this effect requires input from functional otolithic organs of the vestibule."

milinkapoor/Pixabay
Source: milinkapoor/Pixabay

Although using a hammock to rock back and forth while taking an afternoon nap is commonplace, rocking beds for adults are uncommon in the real world. That said a January 4, 2018 press release announced a new patent-pending invention called, wait for it... the “Rocking Bed.” As the company’s tagline states, “The rocking bed is for adults who want to sleep like a baby.”

This mechanized bed is the brainchild of Mark Russell who had a Eureka! moment and decided to invent the so-called “rocking bed” after going on a cruise with his wife and realizing that the gentle swaying of the ship when they were at sea significantly improved their sleep quality.

Once the couple was back on terra firma and home in Atlanta, Georgia, the Russell's wanted to buy an adult-size bed that would gently rock them to sleep like the myriad of automated rocking cradles and baby bassinets manufactured for infants. Unfortunately, nobody had invented or mass-produced a rocking bed for adults. On the eve of his rocking bed invention, Russell is quoted as saying, "With virtually every single human being on earth having been rocked to sleep as babies, how had this never been invented?”

In 1967, inventor Thomas Meeks patented, “Small beds for newborns or infants, e.g. bassinets or cradles with rocking mechanisms.” In 2016, Mark Russell filed a U.S. patent application describing “An apparatus for supporting a mattress of a bed for gentle side to side rocking motion.” To the best of my knowledge, Russell's patent-pending invention is currently the only rocking bed for adults on the market.

For the record: I haven’t tried the Rocking Bed and can’t make any claims about its efficacy for inducing deep sleep or boosting memory consolidation. Anecdotally, Kelly Ripa and Ryan Seacrest were almost lulled to sleep on live national TV while laying on a rocking bed. As Ripa was blissfully swaying on the rocking bed, she exclaimed, “I'm in heaven! This is the happiest I’ve ever been.” A few seconds later she quipped, “This bed is the answer to world peace!”

References

Aurore A. Perrault, Abbas Khani, Charles Quairiaux, Konstantinos Kompotis, Paul Franken, Michel Muhlethaler, Sophie Schwartz, and Laurence Bayer. "Whole-Night Continuous Rocking Entrains Spontaneous Neural Oscillations with Benefits for Sleep and Memory." Current Biology (First published online: January 24, 2019) DOI: 10.1016/j.cub.2018.12.028

Konstantinos Kompotis, Jeffrey Hubbard, Yann Emmenegger, Aurore Perrault, Michel Mühlethaler, Sophie Schwartz, Laurence Bayer, and Paul Franken. "Rocking Promotes Sleep in Mice through Rhythmic Stimulation of the Vestibular System." Current Biology (First published online: January 24, 2019) DOI: 10.1016/j.cub.2018.12.007 

Laurence Bayer, Irina Constantinescu, Stephen Perrig, Julie Vienne, Pierre-Paul Vidal, Michel Mühlethaler, and Sophie Schwartz. "Rocking Synchronizes Brain Waves During a Short Nap." Current Biology (First published: June 21, 2011) DOI: 10.1016/j.cub.2011.05.012

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