Sleep apnea is a serious sleep disorder that occurs when a person's breathing is interrupted during sleep. People with untreated sleep apnea stop breathing repeatedly during their sleep, sometimes hundreds of times during the night.

There are two types of sleep apnea: obstructive and central. Obstructive sleep apnea is the more common of the two. Obstructive sleep apnea occurs as repetitive episodes of complete or partial upper airway blockage during sleep. During an apnea episode, the diaphragm and chest muscles work harder as the pressure increases to open the airway. Breathing usually resumes with a loud gasp or body jerk. These episodes can interfere with sound sleep, reduce the flow of oxygen to vital organs, and cause heart rhythm irregularities.

In central sleep apnea, the airway is not blocked but the brain fails to signal the muscles to breathe due to instability in the respiratory control center. Central apnea is named as such because it is related to the function of the central nervous system.

Sleep apnea is a common sleep disorder characterized by brief interruptions of breathing during sleep. These episodes usually last 10 seconds or more and occur repeatedly throughout the night. People with sleep apnea will partially awaken as they struggle to breathe, but in the morning, they will not be aware of the disturbances in their sleep. The most common type of sleep apnea is obstructive sleep apnea (OSA) caused by relaxation of soft tissue in the back of the throat that blocks the passage of air. Central sleep apnea (CSA) is caused by irregularities in the brain's normal signals to breathe. Most people with sleep apnea will have a combination of both types. The hallmark symptom of the disorder is excessive daytime sleepiness. Additional symptoms of sleep apnea include restless sleep, loud snoring (with periods of silence followed by gasps), falling asleep during the day, morning headaches, trouble concentrating, irritability, forgetfulness, mood or behavior changes, anxiety, and depression. Not everyone who has these symptoms will have sleep apnea, but it is recommended that people who are experiencing even a few of these symptoms visit their doctor for evaluation. Sleep apnea is more likely to occur in men than women, and in people who are overweight or obese.

This answer from the National Institute of Neurological Disorders and Stroke has been reviewed and/or edited by Dr. William D. Knopf.

Sleep apnea is a condition that makes you stop breathing temporarily while you sleep. This forces you to awaken to resume breathing, resulting in disruptive sleep.

People with sleep apnea show marked increases in their blood pressure over time and have a higher level of sympathetic nervous system (SNS) action, research shows.

The SNS plays an important role, controlling heart rate and the constriction of the blood vessels.

Normally, when you sleep, your blood pressure and SNS will taper off gradually. That doesn't happen if you have sleep apnea and you are waking at regular intervals to resume breathing.