Babies aren't the only ones who fall asleep faster when rocked, according to researchers who found that, like infants, adults find it easier to nap on a slowly swinging bed.
Gentle rocking can also improve one's quality of sleep, Swiss researchers reported in the journal Current Biology. The finding may offer hope for those suffering from sleep problems, the authors suggested.
"It is a common belief that rocking induces sleep: we irresistibly fall asleep in a rocking chair and, since immemorial times, we cradle our babies to sleep," study co-author Sophie Schwartz, of the University of Geneva, said in a news release from the journal's publisher. "Yet, how this works had remained a mystery. The goal of our study was twofold: to test whether rocking does indeed soothe sleep, and to understand how this might work at the brain level."
Sleeping on a hammock
In conducting the study, the researchers asked 12 well-rested adults with no history of sleep problems to nap on a custom-made bed or an "experimental hammock" that could remain still or rock gently. As their brain activity was being monitored, each participant took two 45-minute afternoon naps - one in a rocking bed and one in a bed that remained still.
The investigators found that rocking worked by lengthening the duration of stage N2 sleep, which is a form of non-rapid eye movement sleep that accounts for about half of a good night's sleep.
"We observed a faster transition to sleep in each and every subject in the swinging condition, a result that supports the intuitive notion of facilitation of sleep associated with this procedure," study co-author Michel Muhlethaler explained.
The rocking also promoted brain activity associated with deep sleep, by increasing the slow oscillations and bursts of activity known as sleep spindles.
Looking ahead, the study authors noted that more research is needed to determine whether or not rocking can improve more than just naps. This type of motion, they pointed out, may help in the treatment of troubling sleep disorders, including insomnia. The researchers added that rocking may also benefit memory consolidation and potentially help people who've suffered from brain damage by improving brain repair mechanisms.
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