Sleep apnea is a condition in which breathing repeatedly stops and starts during sleep. Sleep apnea is caused by the throat muscles relaxing, blocking the airway, and preventing deep breaths from occurring. Sleep apnea can be treated with positive-pressure ventilation, CPAP machines, or surgery. Sleep apnea symptoms include snoring, waking up with headaches, and feeling tired throughout the day. Sleep Apnea causes can vary from obesity to certain medications or a genetic predisposition. Sleep apnea treatments depend on the severity of sleep apnea but there are many options available including surgery. Information can be found here.
Sleep Apnea is fairly common. Sleep apnea affects approximately 22 million Americans and more than 80 percent of people with sleep apnea are undiagnosed or misdiagnosed. Sleep Apnea can lead to diabetes, heart attack, stroke, depression, attention deficit disorder in children, and many other health issues if left untreated. See here for information about The Dangers of Sleep Apnea.
The most common form of Sleep Apnea is Obstructive Sleep Apnea (OSA) which occurs when throat muscles relax causing tissue in your mouth or nose to obstruct airflow through your windpipe. The resulting pauses in breathing are called "apneas" while you attempt to draw breath against the blockage; these momentary arousals from deep sleep result in fragmented, poor quality rest at night - particularly evident early on during the Sleep Cycle.