Obstructive sleep apnea (OSA) is a disorder in which a person temporarily stops breathing during the night, perhaps hundreds of times. These gaps in breathing are called apneas. The word apnea means absence of breath. An obstructive apnea episode is defined as the absence of airflow for at least 10 seconds.
Obstructive sleep apnea (OSA) occurs when tissues in the upper throat relax and come together during sleep, temporarily blocking the passage of air. In general, OSA occurs as follows:
- On its way to the lungs, air passes through the nose, mouth, and throat (the upper airway).
- Under normal conditions, the back of the throat is soft and tends to collapse inward as a person breathes.
- Dilator (widening) muscles work against this collapse to keep the airway open. Interference or abnormalities in this process cause air turbulence.
- If the tissues at the back of the throat collapse and momentarily block the airway, apnea occurs. Breath is temporarily stopped. In most cases the person is unaware of it, although sometimes they awaken and gasp for breath.
- In some cases, the interference is incomplete (called obstructive hypopnea) and causes continuous but slow and shallow breathing. In response, the throat vibrates and makes the sound of snoring. Snoring can occur whether a person breathes through the mouth or the nose. (Snoring often occurs without apnea.)
- Apnea decreases the amount of oxygen in the blood, and eventually this lack of oxygen triggers the lungs to suck in air.
- At this point, the patient may make a gasping or snorting sound but does not usually fully wake up.
Symptoms of sleep apnea include:
- Excessive daytime sleepiness
- Morning headaches
- Impaired emotional or mental functioning