Breathing coordinates brain waves for memory storage during sleep

Sleep is essential for restoring the body and mind. It’s a time when memories take root and the brain processes the day’s experiences.

While the link between sleep and memory consolidation is well-documented, researchers at Northwestern Medicine have uncovered a surprising player in this intricate process: breathing.

Often dismissed as an automatic function, breathing actually orchestrates memory consolidation through its interaction with hippocampal brain waves, which are rhythmic electrical activities critical for memory storage.

This discovery reveals a fascinating connection between the timing of our breaths and the synchronization of these brain waves during sleep. According to the study authors, this connection is akin to a conductor directing a symphony orchestra.

Breathing: The conductor of brain waves

The novel study, conducted at Northwestern University Feinberg School of Medicine, has identified a direct link between breathing rhythms and three key hippocampal brain waves: slow waves, spindles, and ripples.

These oscillations, previously thought to occur randomly, are now known to synchronize with specific points in the breathing cycle.

“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,” explained study senior author Professor Christina Zelano. “We discovered that they are coordinated by breathing rhythms.”

Unraveling the mystery of memory consolidation

Memory consolidation, the process by which the brain strengthens and organizes information from the day, has long fascinated scientists.

Study co-author Andrew Sheriff, a postdoctoral student in Christina Zelano’s lab, noted that the study sheds light on a critical yet overlooked aspect of memory storage: the role of breathing.

“Memory consolidation relies on orchestration of brain waves during sleep, and we show that this process is closely timed by breathing,” Sheriff said.

The hippocampus is a crucial part of the brain responsible for memory and spatial navigation. It uses these oscillations to replay and organize the day’s experiences. Sheriff related this activity to his personal experience of becoming familiar with navigating a new city.

“The hippocampus plays a major role in forming a map of a new area. 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,” said Sheriff.

The implications of disordered breathing

The findings carry significant implications for individuals with sleep-disordered breathing, such as sleep apnea.

Disruptions to the regular rhythm of breathing during sleep are associated with poor memory consolidation and can increase the risk of neurodegenerative conditions.

“When you don’t get sleep, your brain suffers, your cognition suffers, you get foggy,” Sheriff said. “We also know that sleep-disordered breathing is connected with stroke, dementia, and neurodegenerative disorders.”

This research highlights the importance of seeking treatment for disrupted sleep breathing.

“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,” said Sheriff. “One reason for that may be that breathing is performing a careful task: coordinating brain waves that are related to memory.”

The link between memory and sleep

The link between sleep and memory has fascinated scholars for centuries. Ancient Roman scholar Quintillion once observed: “The interval of a single night will greatly increase the strength of the memory.”

This phenomenon, now known as memory consolidation, is a carefully tuned process involving hippocampal oscillations that modern science has begun to unravel.

“When you’re sleeping, your brain is actively replaying experiences you had during the day,” Sheriff explained.

This replay, which is orchestrated by breathing rhythms, strengthens neural connections and reinforces learning.

Prioritizing sleep health

The study is a wake-up call for individuals experiencing sleep disruptions. Proper breathing during sleep is not just essential for physical health, but also for maintaining cognitive performance.

Disordered breathing, such as in sleep apnea, can disrupt the rhythm necessary for memory consolidation and increase the risk of neurodegenerative conditions like Alzheimer’s disease, dementia, and stroke.

The science of sleep

This research, titled “Breathing orchestrates synchronization of sleep oscillations in the human hippocampus,” represents a collaborative effort by scientists at Northwestern University.

The team included Guangyu Zhou, Justin Morgenthaler, Christopher Cyr, Katherina K. Hauner, Mahmoud Omidbeigi, Joshua Rosenow, Stephan Schuele, and Gregory Lane.

The findings mark a significant step in understanding the hidden mechanisms of memory consolidation.

As science continues to uncover the intricate interplay between sleep, breathing, and memory, this study serves as a powerful reminder of the profound impact of seemingly simple physiological processes on our cognitive health.

The full study was published in the journal Proceedings of the National Academy of Sciences.

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