Sleep apnea is the general medical term for a pair of conditions - called obstructive sleep apnea and central sleep apnea - that produce dangerous disruptions in the normal breathing patterns of sleeping people. Obstructive sleep apnea (OSA) occurs much more frequently than central sleep apnea, and roughly half of all U.S. combat veterans affected by post-traumatic stress disorder (PTSD) also have symptoms of this breathing disorder. According to the results of a study presented in July 2013 to the Associated Professional Sleep Societies, use of a primary treatment for obstructive sleep apnea also significantly decreases the frequency of nightmare-related symptoms in PTSD-affected veterans. This treatment is called continuous positive airway pressure, or CPAP. Obstructive Sleep Apnea Basics Obstructive sleep apnea gets its name because people with the disorder develop obstructions in their throats that intermittently block the flow of air to the lungs during sleep. The underlying cause of these obstructions is an excessive drop in the normal tension of the throat muscles. In some cases, people with OSA develop complete airway blockages that fully halt the breathing process; in other cases, affected individuals develop partial blockages that still permit some amount of air to flow through. Episodes of apnea can occur frequently or infrequently during each nightly hour of sleep; they can also last anywhere from a few seconds to well over a minute. The National Heart Lung and Blood Institute lists potential consequences of the disorder that include heightened risks for heartbeat irregularities or heart failure, heightened risks for workplace accidents and heightened risks for obesity, hypertension, type 2 diabetes, strokes and heart attacks. Association With PTSD In a study published in 2010 in the American College of Chest Physicians\u2019 Chest Journal, a team of researchers examined the effects of sleep disturbances in U.S. combat veterans diagnosed with PTSD. The authors of this study concluded that various forms of these disturbances appear in the overwhelming majority of PTSD-affected military personnel. They also concluded that obstructive sleep apnea, in particular, appears in fully 54 percent of these individuals. By comparison, only roughly 20 percent of the overall U.S. adult population qualifies for an OSA diagnosis. CPAP Treatment CPAP treatment gets its name because it involves the use of a continuous, low-pressure flow of air to offset the throat muscle collapse associated with obstructive sleep apnea. A pump attached to a tube and mask provides this airflow, and the person receiving treatment wears his or her CPAP mask each night for the duration of the sleeping session. In addition to preventing airway blockages, the pressure provided during treatment can also decrease the frequency of snoring and stop or diminish the blood pressure increases commonly associated with OSA. While doctors can use other methods to treat obstructive sleep apnea, CPAP is the best available option for many individuals. One of the main issues in CPAP use is compliance. Some people find the treatment uncomfortable and inconvenient, especially in the beginning, and eventually stop using their CPAP masks on a regular basis. Doctors can help offset the discomfort of the treatment by changing the type of mask used to deliver air pressure, and most people can find a mask that suits their needs. However, significant numbers of people don\u2019t make the necessary adjustments, and therefore never take all of the steps they can to improve their CPAP compliance. CPAP\u2019s Effects on PTSD Symptoms One of the prominent common symptoms of PTSD is the presence of nightmares that cause the affected individual to relive some aspect of the traumatic event(s) responsible for triggering the disorder\u2019s onset. Some people develop nightmares before or shortly after the end of the 30-day waiting period that\u2019s required before doctors can officially make a PTSD diagnosis. However, others only start experiencing nightmares months or even years after they develop other PTSD-related symptoms. In some cases, the presence of obstructive sleep apnea can lead to the start of nightmares in a person with post-traumatic stress disorder. In the study presented to the Associated Professional Sleep Societies, a multi-institution research team examined the nightmare-related effects of regular CPAP use in combat veterans affected by both obstructive sleep apnea and PTSD. They did this by measuring the number of weekly nightmares prior to CPAP treatment and comparing that number to the number of weekly nightmares experienced after half a year of CPAP use. After making their comparisons, the study\u2019s authors concluded that CPAP can produce meaningful declines in the number of nightmares associated with PTSD. They also concluded that the greatest benefit of treatment appears in individuals who stick to their CPAP prescriptions and use the treatment on a regular basis.