What causes obstructive sleep apnea?
When you fall asleep, the tongue and throat muscles relax and the airway narrows. Extra fat around the neck from obesity, a small jaw, large tonsils or age-related loss of muscle tone make the airway collapse more easily. A breathing pause of 10 seconds or more is an apnea; a major reduction is a hypopnea. Blood oxygen drops and the brain briefly wakes up, fragmenting sleep. Being male, obesity, alcohol and sleeping pills raise the risk.
Diagnosis
An overnight sleep study (polysomnography) records brain waves, breathing, oxygen levels and leg movements to calculate the apnea-hypopnea index (AHI), the number of events per hour. Five or more means sleep apnea, 15 or more is moderate and 30 or more is severe. Home sleep tests are also used. A 2019 estimate found about 936 million adults aged 30–69 worldwide have at least mild OSA and 425 million have moderate or worse.
Health effects
Daytime sleepiness and poor concentration raise the risk of car crashes, and OSA is linked to high blood pressure, atrial fibrillation, stroke and diabetes. It's especially common in people whose blood pressure is hard to control with medication.
Treatment
- CPAP: a mask delivers air at steady pressure to keep the airway open, clearly improving snoring, daytime sleepiness and quality of life.
- Oral appliances: pull the lower jaw forward to widen the airway; used for mild to moderate cases.
- Weight loss and sleep position: side sleeping and cutting back on alcohol help.
- Surgery: tonsil or soft-palate surgery and hypoglossal nerve stimulation are options for selected patients.
In the 2016 SAVE trial, CPAP didn't reduce cardiovascular events in 2,717 people with heart disease, but average use was only 3.3 hours a night—a key limitation.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Is loud snoring always sleep apnea?
- No, but loud snoring with gasping, witnessed pauses in breathing or heavy daytime sleepiness is a reason to ask your doctor about a sleep study.
Sources reviewed: 2026-10-25
References
- Benjafield, A. V., et al. (2019). Estimation of the global prevalence and burden of obstructive sleep apnoea. Lancet Respiratory Medicine, 7(8), 687–698.
- McEvoy, R. D., et al. (2016). CPAP for prevention of cardiovascular events in obstructive sleep apnea. New England Journal of Medicine, 375(10), 919–931.
- Peppard, P. E., et al. (2013). Increased prevalence of sleep-disordered breathing in adults. American Journal of Epidemiology, 177(9), 1006–1014.