Link Between Common Sleep Disorder And High Blood Pressure Discovered

RLS, a common and debilitating sleep disorder, adversely affects the lives of tens of millions of people worldwide. The study findings were conducted by scientists at Emory University with colleagues at deCODE Genetics, Inc., an Icelandic genomics company, and Icelandic physicians at Landspitali in Reykjavik.

The findings will be presented June 12th at the 21st Annual Meeting of the Associated Professional Sleep Societies in Minneapolis, Minn.

RLS is a condition that produces an intense, often irresistible urge to move the legs because of creeping, crawling, tingling or burning sensations. RLS affects approximately 10 percent of the U.S. population, causing considerable discomfort, insomnia and sleep disruption in people of all ages. Symptoms can occur when people are awake or asleep.

David Rye, MD, PhD, professor of neurology at Emory University School of Medicine, director of the Emory Program in Sleep and lead author of the study, says the association between RLS and increased risk for high blood pressure was confirmed with the new study.

"Our results confirm and extend accumulating evidence that periodic leg movements of sleep (PLMs) seen in most RLS patients are associated with increased release of adrenaline," says Dr. Rye.

"Of greatest import, these findings suggest that the clinical significance of PLMs extends beyond sleep disruption and sleepiness," he says. "Our findings indicate that in addition to treating RLS symptoms, effective treatments may also need to target PLMs, particularly in patients at high-risk for cardiovascular disease (e.g., those with strong family histories of premature cardiovascular disease, smoking, etc.).

The 4-year joint study was by Dr. Rye and deCODE Genetics scientist Kari Stefansson MD, PhD, with the goal of advancing the understanding of the pathophysiology and clinical impact of RLS.

The research team recruited 900 Icelanders for the study. Participants provided clinical information and the number of PLMs they experienced per hour of sleep over a period of two to five nights were measured. Age, gender, body mass index (BMI), and PLMs were examined as predictors of hypertension. Researchers found the likelihood of hypertension increased with PLMs severity by 50 percent in participants who experienced more than 30 PLMs per hour of sleep. Older age and higher BMI were associated with increased hypertension risk as has been shown by others, yet, PLMs were associated with hypertension status independent of these two factors.

Donald L. Bliwise, PhD, professor of neurology at Emory University, and Lisa Biilars, MD, a senior resident in Neurology, also contributed to the study.