Pillow talk: Hearing relaxing words while asleep calms the heart

LIÈGE, Belgium — New research out of Belgium gives an entirely new meaning to the phrase pillow talk. Scientists from the GIGA – Center of Research Cyclotron at the University of Liége have uncovered that our bodies and hearts react to external stimuli even while asleep. More specifically, hearing relaxing words while sleeping helps promote a lower heart rate.

Study authors say these discoveries help explain how certain information from the sensory environment can affect sleep quality and shine a light on brain-heart interactions during sleep in general.

The team at ULiège collaborated with scientists at the University of Fribourg in Switzerland to investigate if the human body truly “disconnects” from the external world during sleep. To achieve this, they chose to focus on how the heartbeat changes when we hear different words while asleep. This approach led to the revelation that hearing relaxing words indeed slowed down cardiac activity. The team believes that this lower heart rate is a reflection of deeper sleep. In comparison, neutral words did not result in the same slowing effect.

Researchers Matthieu Koroma, Christina Schmidt, and Athena Demertzi from the GIGA Cyclotron Research Center at ULiège previously already collaborated with a group from the University of Fribourg to analyze brain data using electroencephalogram. Ultimately, that research showed that relaxing words increased deep sleep duration and sleep quality. That earlier work also indicated that we can positively influence sleep using meaningful words.

Couple sleeping in bed
Scientists found that hearing relaxing words while sleeping helps promote a lower heart rate. (© Chad Bridwell – stock.adobe.com)

For this latest round of research, study authors enjoyed an opportunity to analyze cardiac activity (using electrocardiogram) as a means of testing this hypothesis. Their strategy led to the finding that the heart slows down its activity only after the presentation of relaxing, but not control (neutral) words.

Next, the research team compared markers pertaining to both cardiac and brain activity to better understand just how much they contributed to the modulation of sleep by auditory information. Cardiac activity has long been believed directly contribute to the way one perceives the world around them, but most evidence in support of this view has come from experiments where the participants were awake. These results, on the other hand, show that it also holds true while asleep, supplying a fresh perspective on the essential role of bodily reactions beyond brain data when it comes to understanding human sleep.

“Most of sleep research focuses on the brain and rarely investigates bodily activity,” Dr. Schmidt says in a university release.

“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,” Dr. Demertzi explains.

“We shared freely our methodology following the principles of Open Science hoping that the tools that helped to make this discovery will inspire other researchers to study the role played by the heart in other sleep functions,” Dr. Koroma concludes.

The study authors believe their work offers a much more comprehensive view of the modulation of sleep functions by sensory information. By focusing on cardiac responses to sounds, researchers say future studies can conceivably analyze the role the body plays in the way sounds influence emotional processing of memories during sleep.

The study is published in the Journal of Sleep Research.

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John Anderer

Born blue in the face, John has been writing professionally for over a decade and covering the latest scientific research for StudyFinds since 2019. His work has been featured by Business Insider, Eat This Not That!, MSN, Ladders, and Yahoo!

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  1. That’s right. Keep on spreading misinformation to make people sick, weak, and unhealthy—the ultimate dream of every leftist totalitarian tyrant. In the last couple of months, you’ve been trying to convince people that working out, gaining muscle strength, eating protein, consuming meat, and getting fit lead to poorer health and early death. All part of the WEF agenda to eviscerate the masses and wipe out more than 90% of the population, which these socialist elites deem to be unnecessary for the planet.

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