“Having a good night’s sleep means falling asleep rapidly and then staying asleep during the whole night,” said Laurence Bayer from the University of Geneva, Switzerland. “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.”
Bayer and his colleague Sophie Schwartz, also from the University of Geneva, had previously studied the positive benefits of rocking during 45-minute naps. However, they wanted to know if rocking could profoundly impact an entire night’s sleep.
18 volunteers participated in the sleep study. For two nights, half of the participants slept on stationary beds whereas the others slept on gently rocking beds. Those who were rocked fell asleep faster, slept more deeply, and woke up less during the night.
Researchers also tested the participants’ memory by having them study word pairs. They then had participants recall the word pairs each night and each morning. Those who slept in the rocking beds had better recollection of the word pairs than those who didn’t.
Bayer and Schwartz found through further testing that rocking actually caused an syncing up of specific brain oscillations of non-rapid eye movement sleep, which therefore caused a synchronization of the neural activity in the thalamo-cortical networks of the brain responsible for sleep and memory.
Paul Franken from the University of Lausanne, Switzerland then tested the rocking method on mice to see if other species reacted to rocking in a similar manner. Although mice had to be rocked four times faster than humans, the motion helped mice fall asleep faster and stay asleep longer. However, it is not known if the mice slept more deeply.
Furthermore, Franken and his team found that mice who did not have functioning otolithic organs in their ears, those being organs vital to the vestibular system, the sensory system that contributes to balance and spatial orientation, did not experience any of the benefits of rocking during sleep.
“Current tools, such as optogenetics, can help us decipher which structures, or even neuronal populations, receive the stimulus from the otolithic organs and transfer it further to the structures of the sleep circuitry,” Franken said. “Mapping the network of communication between the two systems will provide with basic understanding, as well as novel clinical targets to cope with sleep disorders, like insomnia.”
The findings from both studies may be beneficial in the future for treating patients with insomnia and mood disorders. Older adults who struggle with sleep may also benefit from these findings.