Apnea simply means when you stop breathing. The human airway is surrounded by large muscles such as the larynx or tongue. While we are awake these muscles are tightened, removing any obstruction. However, when you sleep these muscles relax over time. Soon breathing causes the muscles to vibrate, which in turn causes snoring. Eventually the muscles relax enough to completely block the airway. This causes temporary suffocation and your brain interrupts deep sleep in order to gain more control over the muscles. Needless to say, this condition can be very annoying, but it also poses some serious health risks.