Rocking yourself to sleep improves sleep quality and memory — even in grownups
Gentle rocking leads to faster, deeper sleep and beneficial changes in brain waves
Sleep researchers have found that being gently rocked in bed helps healthy adults sleep like babies, as they fall asleep faster, sleep more deeply and rouse less. They also found that rocking leads to changes in brain wave patterns, and might have beneficial effects for memory as well.
Dr. Aurore Perrault, a neuroscientist who specializes in sleep, and a postdoctoral researcher at Concordia Univeristy in Montreal was part of the team, and said their inspiration for the experiment was simple. "When we rock babies, they fall asleep," said Perrault. "So we were wondering, could that work with adults?"
A gentle, rocking bed for adults
To investigate how rocking affects grownups, they had to build an adult sized rocking bed in their sleep lab.
"It's this normal bed (...), except that it's suspended and there is a rotor that push[es] the bed laterally," said Perrault in conversation with Quirks & Quarks host Bob McDonald.
The motion was very gentle. The bed was rocked about 10 centimetres back and forth every four seconds.
Perrault and her colleagues then recruited 18 healthy, young adult volunteers for the experiment. They stayed one night in the lab to get them used to the space. Then they stayed two more nights — one in the rocking bed and one in a stationary bed.
The rocking bed in the researcher's sleep lab. The volunteer is clearly very relaxed. Courtesy Laurence Bayer and Aurore Perrault
Each of the participants was asked to wear a cap with electrodes in it, so the researchers could measure their brain wave activity using an electroencephalogram, or EEG.
The researchers then carefully monitored the volunteers' sleep, using video and monitoring their brain waves.
Adults also benefit from a rocking sleep
They found several benefits for their volunteers when they were rocked while sleeping. They fell asleep faster, spent more time in deep, restorative sleep, and they stayed asleep better — they had fewer "micro-arousals" during the course of the night
They also did a memory test with their volunteers, in which they were asked to memorize a list of pairs of words before sleeping, and then recall the pairs on awakening. Sleeping in a rocking bed improved their performance on the test threefold.
The brain wave measurements offered some explanation for all this. Perrault and her colleagues found that normal brain-wave oscillations that occurred during sleep became more ordered and regular in the rocked sleepers. In fact their brain waves became "entrained" or synchronized with the rocking motion.
She said more regular brain wave oscillations are associated with better sleep and memory consolidation during sleep.
One hypothesis Perrault says the team suggested for why adults, as well as babies respond so strongly to a gentle rocking is that it's "the first sensory experience." We experience a similar rocking in utero as our mothers move around.
Rockabye beds as a therapeutic tool?
So far, Perrault and her colleagues have only tested the effects of a gentle swaying on sleep in healthy adults and in mice. The next step is to see if rocking can provide the same benefits to people who experience difficulty sleeping.
People with sleep disorders, and also the elderly, often complain about difficulties falling asleep or maintaining their sleep.
"So we are really hoping that this would actually help them [to sleep] better," said Perrault. "We have to test it on [those with] insomnia and also in an aging population, which also complain of sleep difficulty, as well as memory decline."