Poor Sleep Quality Raises Risk of High Blood Pressure
Reduced slow-wave sleep is a powerful predictor of hypertension in older men. As one of the deeper stages of sleep, it is characterized by non-rapid eye movement (non-REM), a state from which it is difficult to awaken. Slow-wave sleep is represented by relatively slow, synchronized brain waves (delta activity) on an electroencephalogram. Researchers conducting the Outcomes of Sleep Disorders in Older Men Study found that people with the lowest level of slow-wave sleep had an 80 percent increased risk of developing high blood pressure.
"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., study co-author and Peter C. Farrell, Professor of Sleep Medicine in at Brigham and Woman's Hospital and Beth Israel Deaconess Medical Center, Harvard Medical School in Boston.
Men who spent less than 4 percent of their sleep time in slow-wave sleep were likely to develop high blood pressure during the 3.4 years of the study. Men with reduced slow-wave sleep generally had poorer sleep quality, as measured by a shorter sleep duration and more awakenings at night. They also had more severe sleep apnea compared with men who had higher levels of slow-wave sleep. However, of all measures of sleep quality, decreased slow-wave sleep was the most strongly associated with hypertension. This relationship was observed even after other aspects of sleep quality were considered.
The average body mass index (BMI) of the participants was 26.4 kg./[m..sup.2]. But the study effects of slow-wave sleep were independent of obesity and continued to be seen after the effects of obesity were taken into consideration. The researchers conducted comprehensive and objective evaluation of sleep characteristics related to high blood pressure in 784 men who did not have hypertension. The men were studied at home. The team used Polysomnography to assess brain-wave activity, REM and non-REM sleep, and sleep apnea by measuring breathing disturbances and levels of oxygenation during sleep. …