Today on the Stanford Center for Sleep Sciences and Medicine blog on the Huffington Post, sleep neurologist Mitchell Miglis, MD, explains why individuals with untreated sleep apnea have an increased risk of suffering from heart attack and stroke as well as developing high blood pressure, high cholesterol and diabetes.
Researchers have established that resting blood pressure typically falls by 10 to 20 percent in most individuals during sleep. This is a normal physiological response, mediated by the parasympathetic component of the autonomic nervous system. However, in some individuals, termed "non-dippers," this does not occur. In others, so-called "reverse dippers," blood pressure actually increases by 10 to 20 percent. Non-dippers and reverse dippers are at higher risk for stroke than dippers are. And those with obstructive sleep apnea are much more likely to be non-dippers or reverse dippers.
In addition, whenever there is a sudden arousal from sleep, be it due to a nightmare or to upper airway obstruction from sleep apnea, there is a surge in sympathetic activity. As a result, there is a burst of adrenaline released into the bloodstream, blood pressure shoots up (sometimes extremely high), and -- especially if there is a corresponding drop in blood-oxygen levels as frequently occurs during an apnea -- heart rate can become irregular and dangerous arrhythmias, such as atrial fibrillation may develop.
Furthermore, it is thought that this apnea-induced sympathetic surge carries over into the waking state. Researchers have found that patients with sleep apnea have higher daytime levels of adrenaline and higher resting blood pressure than normal controls. They were, however, able to significantly lower the levels in those treated with continuous positive airway pressure (CPAP), the most common treatment for obstructive sleep apnea.
Previously: How effective are surgical options for sleep apnea?, Experts discuss possible link between sleep disorder and dementia and In mice, at least, uninterrupted sleep is critical for memory
Photo by Becky Wetherington