Poor sleep quality increases risk of high blood pressure

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New research finds that reduced slow wave sleep (SWS) is a powerful predictor for developing high blood pressure in older men.

New research from Brigham and Women's Hospital (BWH) conducted in collaboration with California Pacific Medical Center and six clinical sites across the U.S. finds that reduced slow wave sleep (SWS) is a powerful predictor for developing high blood pressure in older men. This research is published in Hypertension: Journal of the American Heart Association.

"Our study shows for the first time that poor quality sleep, reflected by reduced slow wave sleep, puts individuals at significantly increased risk of developing high blood pressure, and that this effect appears to be independent of the influence of breathing pauses during sleep," said Susan Redline, M.D., a co-author on the study, physician and researcher in the Department of Medicine at BWH, and the Peter C. Farrell Professor of Sleep Medicine at Harvard Medical School. "Good quality sleep is the third pillar of health. Sleep, diet and physical activity are critical to health, including heart health and optimal blood pressure control. Although the elderly often have poor sleep, our study shows that such a finding is not benign. Poor sleep may be a powerful predictor for adverse health outcomes and initiatives to improve sleep may provide novel approaches for reducing hypertension burden."

Using standardized in-home sleep studies, researchers evaluated sleep characteristics related to high blood pressure in 784 men who were on average, 75 years old, who didn't have hypertension. The researchers assessed a wide range of measurements of sleep disturbances, such as frequency of breathing disturbances, time in each sleep state, number of nighttime awakenings, and sleep duration.

Researchers report that men who spent less than 4 percent of their sleep time in SWS were significantly more likely to develop high blood pressure during the 3.4 years of the study. Men with the lowest level of SWS had an 80 percent increased risk of developing high blood pressure. Additionally, men with reduced SWS had poorer sleep quality, as measured by shorter sleep duration and more awakenings at night, and also had more severe sleep apnea than men with higher levels of SWS. SWS is one of the deepest stages of sleep, and is characterized by non-rapid eye movement (non-REM) from which it's difficult to awaken. SWS has also been implicated in learning and memory with recent data also highlighting its importance to a variety of physiological functions, including metabolism and diabetes, and neurohormonal systems affecting the sympathetic nervous system that contribute to high blood pressure.

"When considering of all measures of sleep quality, decreased SWS was the most strongly associated with the development of high blood pressure," Redline said. "Generally, older men and women are more likely to develop high blood pressure than younger people and sleep disorders and poor quality sleep are more common in older adults than in younger ones. Although women were not included in this study, it's quite likely that those who have lower levels of slow wave sleep for any number of reasons may also have an increased risk of developing high blood pressure," Redline said.

The collection and analysis of sleep data were conducted under the direction of Dr. Redline by the BWH Sleep Reading Center. The primary author of the study is Maple Fung, M.D. formerly of the University of California, San Diego. The study is coordinated by the San Francisco Coordinating Center, under the direction of Principal Investigator Katie L. Stone, Ph.D. at California Pacific Medical Center Research Institute.

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BWH Division of Sleep Medicine

Brigham and Women's Hospital (BWH) is a 793-bed nonprofit teaching affiliate of Harvard Medical School and a founding member of Partners HealthCare, an integrated health care delivery network. BWH is the home of the Carl J. and Ruth Shapiro Cardiovascular Center, the most advanced center of its kind. BWH is committed to excellence in patient care with expertise in virtually every specialty of medicine and surgery. The BWH medical preeminence dates back to 1832, and today that rich history in clinical care is coupled with its national leadership in quality improvement and patient safety initiatives and its dedication to educating and training the next generation of health care professionals. Through investigation and discovery conducted at its Biomedical Research Institute (BRI), BWH is an international leader in basic, clinical and translational research on human diseases, involving more than 900 physician-investigators and renowned biomedical scientists and faculty supported by more than $ 537 M in funding. BWH is also home to major landmark epidemiologic population studies, including the Nurses' and Physicians' Health Studies and the Women's Health Initiative. For more information about BWH, please visit Brigham and Women's Hospital.