Vacation and relaxation often conjure up images of a hammock swaying gently in the shade of a palm tree on the beach. How easy it would be to drift off to sleep!
A new study by researchers from University of Geneva in Switzerland offers a basis for why this might actually be the case. They found indicators that the rocking motion similar to that of a hammock caused participants to fall asleep faster and also boosted the quality of their sleep.
A WebMD article by Jennifer Warner describes how the analysis took place. The 12 male volunteers, ages 22-38, each took two 45-minute naps at least one week apart on a custom-made bed. The bed was stationary for one nap, and for the other it had a gentle rocking motion. Participants were well-rested and had no history of insomnia or other sleep disorders. Study co-author Sophie Schwartz of the University said that the team had two main goals:
- To see if rocking actually enhances sleep
- To understand the significance inside the brain
Brain activity of each participant was monitored with an electroencephalogram (EEG) during the study to help determine any neurological effects of the movement.
Rocking and the Brain
Mothers have known for eons that rocking or swaying will usually soothe a baby enough to fall asleep, and here’s one reason why: the slow, back-and-forth movement actually increases the quick bursts of activity and the slow oscillations called “sleep spindles” in the brain. Deep sleep and memory consolidation are associated with sleep spindles, according to the WebMD article.
Their test also showed that it lengthened the duration of non-rapid eye movement (stage N2) sleep, which makes up about 1/2 of a normal night’s sleep. It also slightly modified brain activity during N2, taking on the characteristics of deep sleep for all the study participants. The UK’s National Health Service (NHS) Choices website explains the sleep cycle this way:
Sleep normally happens in cycles of non-rapid eye movement (NREM) and rapid eye movement (REM). NREM is further divided into three types: N1, N2 and N3. A sleep cycle normally follows the pattern: N1-N2-N3-N2-REM.
In addition, stage N1 was shorter than normal when volunteers were on the rocking bed.
The study cannot provide definitive conclusions until it’s performed on a larger scale with expanded scenarios. Additionally, test volunteers were healthy, so researchers are unable to accurately predict a similar outcome for those with sleeping disorders. However, the study indicates that this kind of motion may have potential for helping those with sleep disorders.