Sleep apnea (or sleep apnoea in British English; //) is a type of sleep disorder characterized by pauses in breathing or instances of shallow or infrequent breathing during sleep. Each pause in breathing, called an apnea, can last from at least ten seconds to several minutes, and may occur 5 to 30 times or more an hour. Similarly, each abnormally shallow breathing event is called a hypopnea. Sleep apnea is classified as a dyssomnia, meaning abnormal behavior or psychological events occur during sleep. When breathing is paused, carbon dioxide is building up the bloodstream. Chemoreceptors in the blood stream note the high carbon dioxide levels. The brain is signaled to wake the person sleeping and breathe in air. Breathing normally will restore oxygen levels and the person will fall asleep again. Sleep apnea is often diagnosed with an overnight sleep test called a polysomnogram, or "sleep study".
There are three forms of sleep apnea: central (CSA), obstructive (OSA), and complex or mixed sleep apnea (i.e., a combination of central and obstructive) constituting 0.4%, 84% and 15% of cases respectively. In CSA, breathing is interrupted by a lack of respiratory effort; in OSA, breathing is interrupted by a physical block to airflow despite respiratory effort, and snoring is common. According to the National Institutes of Health, 12 million Americans have OSA. There are more cases of sleep apnea still because people either do not report the condition or do not know they have sleep apnea.
Regardless of type, an individual with sleep apnea is rarely aware of having difficulty breathing, even upon awakening. Sleep apnea is recognized as a problem by others witnessing the individual during episodes or is suspected because of its effects on the body (sequelae). Symptoms may be present for years (or even decades) without identification, during which time the sufferer may become conditioned to the daytime sleepiness and fatigue associated with significant levels of sleep disturbance.
Sleep apnea affects not only adults but some children as well. As stated by El-Ad, "patients complain about excessive daytime sleepiness (EDS) and impaired alertness". In other words, common effects of sleep apnea include daytime fatigue, a slower reaction time, and vision problems. OSA may increase risk for driving accidents and work-related accidents. If OSA is not treated, one has an increased risk of other health problems such as diabetes. Even death could occur from untreated OSA due to lack of oxygen to the body. Moreover, patients are examined using “standard test batteries” in order to further identify parts of the brain that are affected by sleep apnea. Tests have shown that certain parts of the brain cause different effects. The “executive functioning” part of the brain affects the way the patient plans and initiates tasks. Second, the part of the brain that deals with attention causes difficulty in paying attention, working effectively and processing information when in a waking state. Thirdly, the part of the brain that uses memory and learning is also affected. Due to the disruption in daytime cognitive state, behavioral effects are also present. This includes moodiness, belligerence, as well as a decrease in attentiveness and drive. Another symptom of sleep apnea is waking up in sleep paralysis. In severe cases, the fear of sleep due to sleep paralysis can lead to insomnia. These effects become very hard to deal with, thus the development of depression may transpire. There is also evidence that the risk of diabetes among those with moderate or severe sleep apnea is higher. There is also increasing evidence that sleep apnea may also lead to liver function impairment, particularly fatty liver diseases (see steatosis). Finally, because there are many factors that could lead to some of the effects previously listed, some patients are not aware that they suffer from sleep apnea and are either misdiagnosed, or just ignore the symptoms altogether.
Sleep Apnea Awareness Day is April 18 every year. April 18 recognizes Colin Sullivan's invention of the CPAP machine and technology. In 1981 he released his study with results of five patients suffering from sleep apnea and successfully used the CPAP machine. The American Sleep Apnea Association (ASAA) believes the CPAP machine greatly changed the treatment and regulation of sleep apnea. Research found using this sleep technology allowed for a better night's sleep and reduced related conditions like diabetes, depression, and hypertension.