What causes sleep apnea?

Short Answer

Sleep apnea is usually caused by repeated airway collapse during sleep (obstructive apnea) due to anatomy, reduced muscle tone, and factors like weight, alcohol, and nasal obstruction. Less commonly, the brain’s breathing control is unstable (central apnea).

Why This Matters

This matters because breathing interruptions cause oxygen drops and arousals, which leads to fragmented sleep and strong daytime fatigue even if you slept “all night.” Over time, repeated stress responses result in higher blood pressure, worse metabolic health, and increased cardiovascular risk. Recognizing causes leads to effective treatment (CPAP, oral appliances, positional changes, weight management).

Where This Changes

People can have apnea at any weight, and symptoms vary—some snore loudly, others don’t. Alcohol and sleeping on your back can worsen apnea, and if you have witnessed apneas or significant sleepiness, a sleep study is the best next step.