Sleep Apnea - Central and Obstructive Sleep Apnea

Medically reviewed by: Stephanie Curreli, MD, PhD
Last Updated: Mar 1, 2019


Sleep apnea is a disorder in which a person repeatedly stops breathing during sleep. This disorder is characterized by episodes of shallow breathing or long pauses (apneic events).

cross section of throat and upper airway

Sleep apnea commonly occurs in both children and adults. The condition affects both men and women, but it is much more prevalent in men.

Types of Sleep aAnea

  1. Obstructive sleep apnea is the most common type of sleep apnea. The problem occurs when muscles of the throat relax during sleep. Such relaxation allows the soft tissues in the back of the throat (soft palate and uvula) to collapse and block airflow into the lungs. Loud snoring occurs as air moves in the narrowed passageway. There are shallow breaths, long pauses, and choking sensations. Episodes of sleep apnea decrease the blood oxygen level, triggering the brain to urgently jolt the person awake and open the airway. The brain immediately falls back to sleep and the cycle of sleep apnea starts over again. Many individuals experience numerous disruptive cycles of sleep apnea an hour.
  2. Central sleep apnea is a rarer form of sleep apnea, caused by a disorder in the part of the brain that controls breathing. This condition may also be triggered by medications that affect the brain functions.


Overweight or obese people are more likely to develop obstructive sleep apnea because of an increased amount of fat in the airway tissues. In children, sleep apnea is often associated with enlarged tonsils and adenoids.

Risk factors for obstructive sleep apnea include:

In central sleep apnea, the brain malfunctions and fails to properly maintain breathing. This disorder can be caused by heart failure or stroke. Central sleep apnea is more prevalent in people over age 60.


Individuals with sleep apnea are typically unaware of their condition and have no recall of the apneic episodes occurring while they are asleep. Family members or bed partners observe loud snoring, repeated apneic events, choking, and gasping during sleep. Sleeping on the back exacerbates these episodes compared to sleeping on the side.

People with sleep apnea experience numerous sleep interruptions all night long. This problem deprives their bodies of deep restorative sleep, causing numerous daytime symptoms.

The following symptoms are frequently associated with sleep apnea:

Complications Resulting from Untreated Sleep Apnea

Over time, the frequent drops in blood oxygen level and poor sleep quality cause harmful increases in stress hormones and serious complications may occur, including:


The diagnosis is easily missed because people with the condition are asleep when the problem is occurring. Since not everyone who snores has sleep apnea, a complete medical evaluation is required. The physical examination of a person with obstructive sleep apnea may reveal an enlargement of the tongue, tonsils, or uvula. Often further testing is required to confirm the diagnosis.

Sleep study

During a sleep study, sensors are applied to monitor a person’s breathing, vital signs, and oxygen level during sleep. This test, known as polysomnography, is usually performed overnight in a special sleep center.



Maintaining normal body weight is a very important factor in decreasing the risk for obstructive sleep apnea. Other lifestyle choices, such as quitting smoking and avoiding excess alcohol, are also beneficial.


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Tina Shahian, PhD

Tina is a Life Science Writer for a number of online publications, including Her expertise is in conveying complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. In her spare time, she enjoys drawing science-related cartoons.