Richard A. Friedman, The Neuroscience of ‘Rock-a-Bye Baby, NYTimes, 10 Feb 2019:
Want to fall effortlessly into profound slumber and sleep like a baby? Everyone knows that infants can be lulled to sleep by gentle rocking. Well, now it seems that what works for babies works for adults, too.
New research shows that a slow rocking motion not only improves sleep but also can help people consolidate memories overnight. And this, in turn, tells us something interesting about how much the brain is affected by what seem to be purely physical interventions.
The researchers found that rocking induced a kind of synchrony in brain wave activity that varied in tandem with the external motion. Rocking also increased the number of brain oscillations specific to sleep, which are critical for memory consolidation and learning. Though the exact mechanism is unclear, the researchers hypothesize that rocking activates motion-sensitive neurons in the inner ear, which then leads to modulation of brain activity.
All this made me wonder: How does physical movement affect the brain more broadly? It’s well known that exercise enhances cognitive functioning, but what about movements like rocking that involve minimal exertion? What effect on the brain do our seemingly purposeless everyday physical movements have — like fidgeting, foot shaking and doodling, among others?
A 2016 study showed that children with A.D.H.D. who were allowed to fidget — bouncing around and moving gently in place — performed better on a concentration task the more they moved.
Another study focused on doodling. Researchers had 40 participants monitor a boring telephone message for the names of people attending a party. Half the group was randomly assigned to doodle — they shaded printed shapes — while listening to the message. The study found that the “doodling group performed better on the monitoring task and recalled 29 percent more information on a surprise memory test.”