Looking for better sleep? Lose the white-noise machine and listen to your brain's own rhythms, suggests a study.
During deep sleep, the brain's electrical patterns follow a slow oscillating rhythm, notes a research team headed by Jan Born of the University of Tubingen in Germany. Some sleep researchers have induced these rhythms in rats with "pathological" sleep patterns, using electrical stimulation in a bid to make them sleep better.
But what about just playing back sleepers' own brain rhythms to them instead? In the journal Neuron, Born and colleagues played rhythmic sounds generated to match electrical brain readings of 11 sleepers, playing the sounds of their own brain oscillations to them during deep sleep. "The beauty lies in the simplicity," Born said in a statement.
In the study, the researchers exposed the sleepers to light rhythmic noise both in sync and out of sync with their brain's oscillations during deep sleep. The in-sync sounds appear to have strengthened the brain rhythms, the researchers found, while also strengthening memories: volunteers were better able to retain word associations they had learned the night before. The out-of-sync sounds didn't have any effect.
Unlike electrical stimulation, playing soft sounds to sleepers poses no risks, the study notes, beyond the trouble of attaching electroencephalograph leads to their scalps to monitor results for the study.
Besides improving memories, the researchers suggest that brain rhythms might improve sleep for insomniacs. "Moreover, it might be even used to enhance other brain rhythms with obvious functional significance -- like rhythms that occur during wakefulness and are involved in the regulation of attention," Born says.
But don't rush out to buy yourself a slow sleep sounds recording right away. "The method cannot be applied by everyday people, at the moment, because the essential point is the 'closed-loop' fashion of our stimulation, using the brain's own rhythm as a pacemaker," Born says, where electroencephalograph readings predicted just when to deliver the next noise to sleepers to improve their sleep.
"Of course, basically it should be easy to develop a device that records the EEG (electroencephalograph) and searches the record online for the occurrence of a slow oscillation and then delivers acoustic click stimuli," to someone sleeping, Born adds by email. "Maybe there will be a company adopting the approach to make some money out of it."