Sleep apnea is a disorder where a person experiences a sequence of shallow breaths or pauses in breathing while sleeping. The duration of the pauses varies from a few seconds to minutes and they usually occur repeatedly throughout the night, often leaving the individual feeling sleep deprived the next morning.

About half of the people with Obstructive Sleep Apnea (the most common type) also have hypertension and there is mounting evidence indicating that treatment of sleep apnea via CPAP machines can significantly reduce blood pressure.

Both severe and minor Symptomatic Obstructive Sleep Apnea have been tied to endothelial dysfunction, a situation in which the cells that line blood vessels, arteries and veins throughout the body do not expand as needed often leading to increased blood pressure. When the body goes though periods of not receiving enough oxygen, as it does with sleep apnea, there is a decrease in nitric oxide production. Sufficient nitric oxide is essential for proper endothelial function and not enough prohibits the endothelium from behaving properly. There is also evidence to suggest that sleep apnea results in increased sympathetic activity, a known contributor to hypertension.

Malcolm Kohler, Sonya Craig, Debby Nicoll, Paul Leeson, Robert J. O. Davies, John R. Stradling. Endothelial Function and Arterial Stiffness in Minimally Symptomatic Obstructive Sleep Apnea. American Journal of Respiratory and Critical Care Medicine.2008:178;984-988. Available at: http://ajrccm.atsjournals.org/cgi/content/abstract/178/9/984. Accessed June 8, 2009.

Ali A. El Solh, Morohunfolu E. Akinnusi, Fadi H. Baddoura, Corey R. Mankowsi. Endothelial Cell Apoptosis in Obstructive Sleep Apnea. American Journal of Respiratory and Critical Care Medicine. 2007;175:1186-1191. Available at: http://ajrccm.atsjournals.org/cgi/content/full/175/11/1186. Accessed June 8, 2009.

Amy Atkeson and Sanja Jelic. Mechanisms of endothelial dysfunction in obstructive sleep apnea. Vasc Health Risk Manag. 2008 December; 4(6): 1327–1335. Available at http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2663447. Accessed June 8, 2008.

Mary S. M. Ip, Hung-Fat Tse, Bing Lam, Kenneth W. T. Tsang and Wah-Kit Lam. Endothelial Function in Obstructive Sleep Apnea and Response to Treatment. American Journal of Respiratory and Critical Care Medicine. 2004;169:348-353.Available at: http://ajrccm.atsjournals.org/cgi/content/full/169/3/348. Accessed June 8, 2008.