Sleep apnea is a disorder in which breathing repeatedly stops and starts during sleep. The most common form, obstructive sleep apnea, occurs when soft tissue in the throat collapses and blocks the airway.

Episodes can last from a few seconds to more than a minute and may occur dozens or hundreds of times per night. Each interruption briefly arouses the sleeper, fragmenting sleep architecture and preventing restorative deep and REM stages. Loud snoring, gasping, and excessive daytime sleepiness are typical signs. Risk factors include obesity, male sex, older age, and anatomical features that narrow the airway.

Untreated sleep apnea is associated with hypertension, heart disease, stroke, and impaired cognitive function. Continuous positive airway pressure (CPAP) is the most effective treatment for moderate to severe cases; weight loss, positional therapy, and oral appliances help some people. Diagnosis is confirmed by overnight sleep study.

When breathing repeatedly fails during the night, both sleep and long-term health suffer.