Deep Sleep With Pink Noise Increases Benefits to Cardiovascular System

Deep sleep with auditory stimulation poses benefits to the heart, specifically the left ventricle, causing it to contract and relax more vigorously, according to the results of a study from the University of Zurich. Investigators noted that blood is pumped more efficiently through the circulatory system, which will benefit most organs, extremities, and the brain.¹

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In the study (NCT04166916), published in the European Heart Journal, investigators used echocardiography, or cardiac ultrasound examinations, to show how the left ventricle changes after a auditory stimulation. According to a statement, this is the first time that research has shown an increase in brain waves during deep sleep that improved cardiac function.¹

“We were expecting that stimulation with tones during deep sleep would impact the cardiovascular system, but the fact that this effect was so clearly measurable after just 1 night of stimulation surprised us,” Caroline Lustenberger, PhD, Swiss National Science Foundation Ambizione Fellow at the Neural Control of Movement Lab at ETH Zurich, said in the statement.¹

There were 18 individuals included in the study, who were non-smokers and had no cardiovascular disease, sleep disorders or comorbidities, or significant concomitant diseases, according to the study authors. They spent 3 non-consecutive nights in a sleep laboratory, in which investigators stimulated the individuals with sounds on 2 nights.^1,2

The investigators continuously measured the individual’s brain activity, blood pressure, and heart activity during sleep. The measurements were simultaneously uploaded into a computer to analyze the data.¹

When the individual fell into deep sleep, a series of brief tones at frequencies known as pink noise played. The series was 10 seconds of pink noise, followed by 10 seconds of silence, then repeated. Investigators monitored whether the sound enhanced deep sleep and whether it influenced the individual’s heart rate and blood pressure. In the morning, the investigators examined the cardiac function of the individual.¹

The study authors reported that the pink noise stimulation during sleep significantly and globally enhanced slow waves, and influenced cardiovascular functions. There were no significant differences in the condition of absolute systolic blood pressure, according to the results; however, after corrections made to baseline data, investigators found a small, but consistent, increase in relative systolic blood pressure.²

Furthermore, the study authors observed a significant increase in the left ventricular, with a significant increase in left ventricular ejection fraction and a significant decrease in the left ventricular E/e′ ratio. They determined that the results indicate improvements in left ventricular systolic and diastolic functions for the pink noise stimulation. Additionally, the blood biomarkers and carotid-femoral pulse wave velocity showed no significant effect on the stimulation overnight.²

“Despite the relatively small group of subjects, the results are significant. We were also able to reproduce the results on 2 separate nights, which in statistical terms makes them very strong,” Lustenberger said in the statement.¹

She added that future studies should include those who are female due to sex differences in sleep and cardiovascular health, especially because the menstrual cycle and menopause have major effects on sleep.¹

Investigators will also look to research more powerful stimulation methods to determine the impact on the cardiovascular system.¹

References

1. Increased deep sleep benefits your heart. News release. EurekAlert. October 5, 2023. Accessed October 13, 2023. https://www.eurekalert.org/news-releases/1003820
2. Huwiler S, Carro-Domínguez M, Stich FM, Sala R, et al. Auditory stimulation of sleep slow waves enhances left ventricular function in humans. Eur Heart J. 2023;ehad630. doi:10.1093/eurheartj/ehad630