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- Babies are soothed by being rocked to sleep.
- There’s some evidence it’s good for adults too.
- Researchers in Switzerland tested rocking adults to sleep.
- They found rocking helped people spend more time in deep sleep – the stage which helps build our memories.
- The results could help find treatments for people who suffer with insomnia, and for older people who struggle falling asleep and commonly have memory problems.
There’s nothing more relaxing than swinging in a hammock. Something about rocking from side to side not only puts babies to sleep, but adults too.
A new study from the University of Geneva in Switzerland, published in the journal Current Biology, examined the effect rocking could have on our sleep.
Scientists recruited 18 young adults to take part in a sleep lab. On the first night they got used to their surroundings, then they stayed two more nights, one of which was spent on a gently rocking bed.
Previous research had shown continuous rocking during a 45 minute nap helped people fall asleep quicker and snooze more soundly, so the team were curious about how rocking the entire night could affect brain waves and sleep quality.
“Having a good night’s sleep means falling asleep rapidly and then staying asleep during the whole night,” said Laurence Bayer, one of the authors. “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.”
Participants spent less time in the first few stages of sleep, and more time in non-rapid eye movement sleep. They also spent more time in deep sleep, and woke up less.
Sleeping well helps keep our memory fresh
Rocking also increased the amount of “sleep spindles,” which are sudden bursts of oscillatory brain activity that happen during the second stage of light sleep. Sleep spindles have been associated with the replaying of memories, helping us make sense of the days activities, and remember things better.
To test the participants’ memories, the team asked them to study word pairs. They tested how well the subjects recalled those paired words in an evening session then again when they woke up the next day. People who were rocked through the night performed better on the memory tests than those who weren’t.
“The present human experiment thus provides new insights into the neurophysiological mechanisms underlying the effects of rocking stimulations on sleep,” the researchers wrote.
“These results may be relevant for the development of non-pharmacological therapies for patients with insomnia or mood disorders, or even for aging populations, who frequently suffer from decreased deep sleep and/or from memory impairments.”
Sophie Schwartz, another author of the study, told the BBC the research could help explain why people fell asleep so easily on trains.
“I was contacted by someone in America who works on a high crane, which moves gently all day,” she said. “He told me that now he understands why he sleeps so deeply during his after-lunch nap.”