Whispered dreams: How relaxing words tune our heartbeat to sleep

Researchers have discovered that our bodies remain attuned to the external environment even as we sleep, reacting positively to relaxing words spoken to the brain during deep stages of slumber.

This revelation was unveiled in a fascinating study conducted by the GIGA – Center of Research Cyclotron (GIGA-CRC) at the University of Liège, in collaboration with the University of Fribourg, Switzerland.

Their study challenges the long-held belief that sleep disconnects us from our surroundings, highlighting the intricate ways in which sensory information can influence the quality of our rest.

Listening to relaxing words while sleeping

The research focused on the interaction between the brain and the heart during sleep, specifically investigating how our heartbeat responds to auditory stimuli.

The study found that hearing relaxing words while sleeping can slow down cardiac activity, indicating a state of deeper, more restful sleep compared to when neutral words are heard.

This fascinating discovery provides insight into the complex brain-heart interactions that occur during sleep and opens up new avenues for enhancing sleep quality through auditory stimuli.

Leading the research was Matthieu Koroma, a postdoctoral researcher with the Fund for Scientific Research (FNRS). Working alongside was Christina Schmidt and Athena Demertzi, both FNRS Research Associates at the GIGA Cyclotron Research Center at ULiège.

Symphony of sleep: The brain-heart connection

Previously, this team had established that relaxing words can extend the duration of deep sleep and improve sleep quality by analyzing brain activity through electroencephalograms.

This earlier work laid the groundwork for the current study, which sought to explore how the heart’s response to these words during sleep could further influence sleep quality.

By analyzing cardiac activity through electrocardiograms, the team was able to confirm their hypothesis that the heart indeed slows down following the presentation of relaxing words, but not in response to neutral or control words.

Power of relaxing words during sleep

This finding underscores the potential of using meaningful words to positively affect sleep, demonstrating that our brains and bodies are capable of processing and responding to sensory information in a way that promotes relaxation during sleep.

The study also compared markers of cardiac and brain activity to better understand the interplay between auditory information and sleep modulation.

This comparison sheds light on the essential role that bodily reactions play in our comprehension of sleep, beyond what brain data alone can reveal.

As Dr. Schmidt notes, most sleep research has traditionally focused on the brain, often overlooking the significance of bodily activity.

This research, however, emphasizes the interconnectedness of the brain and body, even in states where communication seems limited, such as during sleep.

Bridging body and mind: Unseen ties that bind

Dr. Demertzi elaborates on the importance of considering both brain and body information for a comprehensive understanding of our reactions to the environment, suggesting that this holistic approach can enhance our knowledge of how sensory information modulates sleep functions.

“We nevertheless hypothesize that the brain and the body are connected even when we cannot fully communicate, including sleep. Both brain and body information need then to be taken into account for a full understanding of how we think and react to our environment”, explains Dr. Demertzi.

In the spirit of Open Science, the researchers have made their methodology publicly available, encouraging other scientists to explore the heart’s role in various sleep functions.

Dr. Koroma expresses hope that the tools and findings from this study will inspire further research into how the body, particularly the heart, interacts with sensory information during sleep.

This pioneering work adds a new dimension to our understanding of sleep opens new doors for innovative approaches to improving sleep quality.

Future research could explore how the body’s responses to sounds affect emotional processing of memories during sleep, offering new perspectives on the role of the body in sleep and cognition.

Embracing whispers in the night

In summary, this fascinating study from the University of Liège and FNRS, fundamentally shifts our understanding of sleep by revealing that our bodies, contrary to prior beliefs, remain in tune with external sensory stimuli during sleep.

This research highlights how the subtle influence of relaxing words can significantly slow cardiac activity, leading to deeper, more restorative sleep.

By bridging the gap between brain and heart responses, the study opens up new avenues for enhancing sleep quality through auditory stimulation.

As we continue to unravel the complex interactions between our environment and our sleep states, this paves new roads for innovative sleep improvement strategies, emphasizing the importance of a holistic approach to sleep science that considers both the mind and the body.

The full study was published in the Journal of Sleep Research.

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