A new study from Northwestern Medicine uncovers how breathing rhythms during sleep coordinate brain waves in the hippocampus, playing a crucial role in memory consolidation and emphasizing the importance of addressing sleep-related breathing disorders.
Just as a conductor unifies an orchestra, breathing coordinates the timing of brain waves in the hippocampus to bolster memory during sleep, reports a new Northwestern Medicine study.
For the first time, researchers have linked breathing rhythms during sleep to hippocampal brain waves — specifically, slow waves, spindles and ripples — in humans. While these brain waves have long been associated with memory consolidation, their underlying driver remained a mystery until now.
“To strengthen memories, three special neural oscillations emerge and synchronize in the hippocampus during sleep, but they were thought to come and go at random times,” senior author Christina Zelano, a professor of neurology at Northwestern University Feinberg School of Medicine, said in a news release.
The team discovered that they are coordinated by breathing rhythms.
The research, published in the Proceedings of the National Academy of Sciences, reveals that hippocampal oscillations align with specific points in the breathing cycle, underscoring the critical role of breathing rhythms in memory consolidation during sleep.
“Memory consolidation relies on orchestration of brain waves during sleep, and we show that this process is closely timed by breathing,” corresponding author Andrew Sheriff, a postdoctoral student in Zelano’s lab, said in the news release.
These findings carry significant implications for individuals with disordered breathing during sleep — conditions like sleep apnea — which are linked to impaired memory consolidation.
Historical observations support this discovery. As far back as ancient Rome, the scholar Quintilian noted the remarkable enhancement of memory following sleep. Modern science explains this as memory consolidation, a process orchestrated by finely tuned synchronization of brain waves in the hippocampus.
“When you’re sleeping, your brain is actively replaying experiences you had during the day,” added Sheriff.
He recounted a personal experience following a trip to Reykjavik, Iceland.
“The hippocampus plays a major role in forming a map of a new area,” he added. “I would wake up and feel I had a better representation of the city around me. That was facilitated by the oscillations that occurred during my sleep, which we found are coordinated by breathing.”
The study suggests that individuals with disrupted sleep-related breathing issues should consider seeking treatment. Addressing these issues could have profound effects on cognitive function and overall brain health.
“When you don’t get sleep your brain suffers, your cognition suffers, you get foggy,” added Sheriff. “We also know that sleep-disordered breathing is connected with stroke, dementia and neurodegenerative disorders like Alzheimer’s Disease.”
Sheriff also mentioned an interesting observation about sleep.
“If you listen to someone breathing, you might be able to tell when they are asleep, because breathing is paced differently when you’re sleeping,” he explained. “One reason for that may be that breathing is performing a careful task: coordinating brain waves that are related to memory.”