Contact: Ryan C. Brindle, Ph.D.
For Release: Immediately
Deep sleep may provide a surprising buffer against the toll that daytime acute stress can take on the heart, suggests a unique new study published online by the American Psychosomatic Society (APS). The two-night lab study will appear in a forthcoming issue of Psychosomatic Medicine, journal of the American Psychosomatic Society.
The study measured overnight sleep, how 99 adults’ heart rates responded to a number-matching exercise that induces stress, and the inner layers of their neck artery walls. After acute stress—heavy traffic, a fraught meeting with the boss–higher jumps in heart rate and blood pressure have been linked to thicker neck artery walls. And the thicker these carotid walls are, the greater your risk for heart attack and stroke, scientists believe. During slow-wave or deepest sleep, our blood pressure falls to its 24-hour nadir.
In the study, among those who spent the least amount of slumber time in deep or slow-wave sleep—averaging just 3.6% of the time–higher heart-rate and blood pressure increases after stress were tied to thicker artery walls. In fact, the greater the body’s reaction to stress, the thicker the walls, says Ryan C. Brindle, Ph.D., of the Dept. of Psychiatry at University of Pittsburgh, senior author of the study, with coauthor and colleague Martica H. Hall. That link did not appear for those with a higher percentage of deep sleep—17%. The researchers controlled for age, sex, and socioeconomic status, which affect artery thickness, and the findings remained significant.
Plenty of slow-wave sleep also has been found to be important for memory because slower brain waves rest the neurons.
“In our study, deep sleep seems to be functioning as a protective buffer against blood pressure surges caused by stresses during the day,” says Brindle. “If you don’t get enough slow-wave, it may be like going to the gym seven days a week; your body never has a chance to repair. We think when your blood pressure goes down in slow-wave sleep your blood vessels may have a window of time to repair and perhaps cope with daytime stress in a way that’s less damaging to the cardiovascular system.”
There is hope, though, for chronic light or fitful sleepers. Exercise and mental activity have been shown to promote slow-wave sleep, Brindle adds, and he recommends both.
The American Psychosomatic Society (APS) (www.psychosomatic.org), founded in 1943, is an international multidisciplinary academic society that organizes an annual scientific meeting and educational programs. Psychosomatic Medicine is its scientific journal. The membership of over 700 is composed of academic scientists and clinicians in medicine, psychiatry, epidemiology, health psychology and allied health services. The mission of the APS is “to advance and integrate the scientific study of biological, psychological, behavioral and social factors in health and disease.”