Learn about sleep apnea, including: the definition, the various causes, the classic symptoms, the important consequences, and the diagnosis. Sleep apnea (or sleep apnoea in British English) is a sleep disorder characterized by abnormal pauses in breathing or instances of abnormally low breathing during sleep. Learn about sleep apnea, including a description of types of sleep apnea, symptoms, treatment (surgical and nonsurgical), causes, complications, diagnosis, evaluation Find in-depth information on sleep apnea, including symptoms ranging from loud snoring to headaches and irritation.