Sleep is transformative in more ways than we know.
Sleep specialists, including Sujith Vijayan, have found that sleep’s beneficial brain rhythms can be enhanced by another type of rhythm: sound waves.
“By playing sounds during sleep, we can change brain dynamics and improve learning and memory,” said Vijayan, who is an associate professor in Virginia Tech’s School of Neuroscience.
Sleep can act like a memory booster — taking a nap might help more on a test than last-minute cramming — but it may also be important for what Vijayan calls cerebral “housekeeping.”
“It turns out the blood vessels in your brain get bigger while you sleep, so sleep is how your body cleans out a lot of the everyday toxins,” Vijayan said.
In Vijayan’s experimental studies, research participants engage in certain learning tasks and then fall asleep in a sleep room wearing an EEG (electroencephalogram) headcap to record brain waves. Researchers monitor participant electrical brain waves and play soft sounds when the waves reach critical moments.
Electrical brain waves vary in frequency with the different stages of sleep. The first part of a sleep cycle is usually deep, restorative sleep. Rapid eye movement (REM) sleep, which comes later in the cycle, is also called paradoxical sleep because the brain activity looks like an alert, wakeful brain.
The realm of vivid dreams, REM sleep is also the realm for processing emotional memories. Vijayan is using auditory stimulation to probe this chaotic, critical stage of sleep.
In one computational modeling study published recently in the Journal of Neuroscience, Vijayan explored how these techniques could help restore the healing quality of sleep for people suffering from post-traumatic stress disorder (PTSD).
With support from a National Science Foundation CAREER award, Vijayan is also investigating if the brain’s work during sleep can help people learn tasks associated with brain computer interfaces, which allow an individual to use their brain activity alone to control an external device like a wheelchair or a cursor on a computer screen.
In these and other projects, Vijayan continues to advance understanding of the relationship between sleep rhythms and memory, learning, and housekeeping. In his vision of the future, sound can be used as therapy and medicine to modulate brain waves.
“It’s like when you have an extremely high fever, you take a Tylenol to get your temperature back down,” Vijayan said. “I think we can get to the point that we can restore brain rhythms during sleep so the body can do what it needs to do to heal.”
