How gentle rocking can lull you to sleep
Image Credit: Ramachandra Babu/©Gulf News

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 can also 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.

Scientists at the University of Geneva in Switzerland studied 18 healthy young adults while they slept in the lab for two nights.

Gentle rocking experiment

One night they slept in regular stationary beds; another night they slept in beds that gently rocked from side to side all night.

The order of the rocking and stationary nights was randomised, so that each person served as his or her own control.

The researchers found that rocking caused the subjects to fall asleep more quickly and increased their amount of slow-wave deep sleep, a phase of sleep that is associated with feeling refreshed and rested upon waking.

They also experienced fewer periods of spontaneous arousal.

The researchers found that rocking caused the subjects to fall asleep more quickly and increased their amount of slow-wave deep sleep, a phase of sleep that is associated with feeling refreshed and rested upon waking. They also experienced fewer periods of spontaneous arousal.

- Findings of scientists at the University of Geneva in Switzerland

This was true despite the fact that they were already good sleepers.

Memory consolidation

Rocking did not affect the duration of rapid eye movement or dream sleep.

The study also assessed memory consolidation by having the subjects study word pairs before going to bed.

They were tested on their recall of these words in the evening and then again in the morning when they woke up.

The subjects showed improved recall on the morning test after the rocking night compared with the stationary night, showing that rocking enhanced the accuracy of their memories.

This study was, of course, quite small.

30%

of adults report that they don’t get enough sleep

But other studies have reported similar findings, though the size of the effect appears to depend on the frequency and type of rocking.

Whether and to what extent rocking might help people with severe sleep issues is unknown, but these findings are welcome news for our nation of insomniacs — more than 30 per cent of adults report that they don’t get enough sleep — to say nothing of the rampant use of sleeping pills, which can have harmful effects on cognition and everyday functioning.

Kind of synchrony in brain

It might not be surprising that rocking helps. After all, who hasn’t noticed the soothing effects of swinging in a hammock or lying on a raft on the undulating water? And let’s not forget that we spend the first nine months of our lives being gently rocked in an amniotic sea.

But why does it work? How exactly does a gentle rhythmic motion change the sleep architecture of the brain?

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 hypothesise 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 ADHD 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.

Effect of doodling on memory

The study found that the “doodling group performed better on the monitoring task and recalled 29 per cent more information on a surprise memory test”.

So maybe my grade-school teachers were wrong to scold me for not “paying attention” in class because I was busy doodling or antsy — I might have in fact been enhancing my learning.

And what about the effects of repetitive everyday movements one sees in other areas of life — like during religious rituals?

Does this physical activity enhance the religious experience in some way?

It wouldn’t be surprising if it did, given the fact that many “outside-in” interventions that target the body can also alter our brain and mind — like using Botox to treat depression or acupuncture for pain.

We like to think the brain is sovereign, but it is obvious that it sometimes takes its marching orders from the body.

I imagine some marketing guru is out there right now, inventing a grown-up version of the SNOO — a $1,160 (Dh4,266) robotic bassinet that can gently rock a baby all night long.

When it comes to sleep, Rock-a-Bye Baby isn’t just for children.

— New York Times News Service

Dr Richard A. Friedman is a psychiatrist 
and a contributing opinion writer.