Sleep apnea is a condition where your breathing repeatedly stops and restarts during sleep, sometimes dozens of times per hour. Roughly 80% of cases go undiagnosed, largely because the most telling symptoms happen while you’re unconscious. The pauses in breathing last anywhere from a few seconds to over a minute, and each one triggers a mini stress response in your body that fragments your sleep and, over time, damages your cardiovascular system.
How Sleep Apnea Works
When you fall asleep, your brain dials down the signals it sends to the muscles that keep your airway open. For most people, this slight relaxation doesn’t matter. But if your airway is already narrow, whether from excess tissue, bone structure, or other factors, those muscles can’t hold it open against the pull of gravity and surrounding tissue. The airway either narrows significantly (called a hypopnea) or collapses completely (an apnea), cutting off airflow.
Your chest muscles and diaphragm keep trying to pull air in against the blockage, but nothing gets through. Oxygen levels in your blood drop. Carbon dioxide builds up. After several seconds, your brain registers the emergency and jolts you just awake enough to tense those airway muscles and gasp in a breath. You likely won’t remember these awakenings, but they prevent you from reaching or staying in the deeper stages of sleep your body needs to recover.
Obstructive vs. Central Sleep Apnea
Obstructive sleep apnea (OSA) is by far the more common type. It’s a mechanical problem: your airway physically collapses or gets blocked despite your body’s ongoing effort to breathe. You’re trying to inhale, but the air has nowhere to go.
Central sleep apnea (CSA) is a signaling problem. Your airway isn’t blocked at all. Instead, your brain temporarily stops telling your breathing muscles to work, so you simply don’t attempt a breath. CSA is less common and often occurs alongside heart failure, stroke, or the use of certain medications. Some people have a mix of both types, sometimes called complex sleep apnea.
Common Symptoms
The hallmark sign is loud, chronic snoring, especially snoring that’s interrupted by silent pauses followed by choking or gasping sounds. A bed partner usually notices this before the person with the condition does. Other symptoms develop because of fragmented sleep and repeated drops in oxygen:
- Excessive daytime sleepiness that persists no matter how many hours you spend in bed
- Morning headaches caused by fluctuating oxygen and carbon dioxide levels overnight
- Waking with a dry mouth or sore throat from breathing through an open mouth
- Difficulty concentrating, memory problems, or irritability during the day
- Frequently waking to urinate at night, which happens because the body releases a hormone that increases urine production during apnea episodes
In children, sleep apnea often looks different. Rather than obvious daytime sleepiness, kids tend to show behavioral changes: hyperactivity, trouble paying attention, or poor performance in school. Enlarged tonsils and adenoids are the most common cause in children, and the first-line treatment is usually surgery to remove them.
Who’s Most at Risk
About two-thirds of people with obstructive sleep apnea are overweight or obese. Extra weight, particularly around the neck and throat, adds tissue that can press on the airway during sleep. For men, a neck circumference greater than 17 inches is a significant risk marker. But sleep apnea also affects people at a healthy weight, particularly those with a naturally narrow airway, a recessed jaw, or large tonsils.
Other risk factors include being male (men develop OSA at roughly twice the rate of premenopausal women), being over 40, having a family history of the condition, smoking, and nasal congestion. After menopause, women’s risk rises to nearly match men’s, likely due to hormonal changes that affect airway muscle tone.
What It Does to Your Body Over Time
Each time your breathing stops, your blood oxygen drops and your nervous system kicks into fight-or-flight mode, releasing stress hormones and spiking your blood pressure. When this happens 15, 30, or even 60 times an hour, night after night, the cumulative damage is substantial.
The repeated cycles of oxygen loss and recovery create oxidative stress and chronic inflammation throughout your blood vessels. This accelerates the buildup of plaque in your arteries. Sleep apnea independently raises the risk of high blood pressure, heart attack, heart failure, irregular heart rhythms, and stroke. The link between sleep apnea and stroke goes beyond just elevated blood pressure. It appears to involve changes in blood clotting, disrupted blood flow to the brain, and sustained inflammation in blood vessel walls.
Sleep apnea also disrupts metabolism. Intermittent oxygen deprivation in fat tissue, combined with elevated stress hormones, promotes insulin resistance and makes it harder to manage blood sugar. This creates a feedback loop: metabolic changes encourage weight gain, and weight gain worsens the apnea.
How Sleep Apnea Is Diagnosed
Diagnosis centers on measuring how many times your breathing stops or becomes dangerously shallow per hour of sleep. This number is called the Apnea-Hypopnea Index (AHI). The severity categories for adults are:
- Mild: 5 to fewer than 15 events per hour
- Moderate: 15 to fewer than 30 events per hour
- Severe: 30 or more events per hour
The gold standard test is an overnight sleep study in a lab (polysomnography), where sensors track your breathing, oxygen levels, brain waves, heart rhythm, and body movements. For many people, though, a home sleep test is a reasonable first step. These portable devices measure airflow, breathing effort, and blood oxygen while you sleep in your own bed. Home tests have about 95% sensitivity for detecting sleep apnea overall, meaning they catch the vast majority of cases. They’re somewhat less precise for distinguishing moderate from severe disease, with accuracy around 78% for that distinction. If a home test comes back normal but your symptoms are strong, a full in-lab study is typically the next step.
Treatment Options
CPAP (continuous positive airway pressure) remains the most effective treatment. The machine delivers a steady stream of pressurized air through a mask, acting as a pneumatic splint that keeps your airway open all night. It’s highly effective at reducing apnea events, raising blood oxygen levels, and improving daytime alertness. The challenge is that many people find the mask uncomfortable, noisy, or claustrophobic, and consistent use is what makes it work.
Oral appliances are an alternative, particularly for mild to moderate cases. These custom-fitted devices, made by a dentist, push your lower jaw slightly forward to keep the airway from collapsing. CPAP reduces apnea events more effectively in controlled studies, but oral appliances tend to score higher on patient satisfaction and adherence. Because people actually wear them more consistently, the real-world benefit for daytime sleepiness ends up comparable to CPAP in many cases. For someone who can’t tolerate a CPAP mask, an oral appliance they’ll actually use every night is often the better practical choice.
Weight loss makes a meaningful difference for people whose apnea is connected to excess weight. Losing even 10% of body weight can significantly reduce the number of apnea events per hour, and for some people with mild disease, it can resolve the condition entirely. Positional therapy (training yourself to sleep on your side instead of your back) helps a subset of people whose apnea is worst in the supine position. For more severe or treatment-resistant cases, surgical options exist to remove excess tissue, reposition the jaw, or implant a device that stimulates the nerve controlling tongue movement to keep the airway open during sleep.