Sleep apnea is a condition where your breathing repeatedly stops and restarts during sleep. These pauses can last ten seconds or longer and happen dozens or even hundreds of times per night, pulling you out of deep sleep and starving your body of oxygen. About 34% of adults in the U.S. currently have some form of it, and that number is projected to climb to 46% by 2050.
How Breathing Stops: Two Different Mechanisms
There are two main types of sleep apnea, and the distinction matters because they have different causes and different treatments.
Obstructive sleep apnea (OSA) is by far the more common type. It happens when the muscles in your throat relax too much during sleep, causing the soft tissue to collapse inward and physically block your airway. You’re still trying to breathe, but air can’t get through. This is the type most associated with snoring, gasping, and choking sounds at night.
Central sleep apnea (CSA) is less common and works differently. Your airway stays open, but the brain temporarily stops sending signals to the muscles that control breathing. The result is similar (you stop breathing), but the root cause is neurological rather than structural. Some people have both types simultaneously, which is called complex sleep apnea.
Symptoms Beyond Snoring
Loud snoring is the symptom most people associate with sleep apnea, but many of the telltale signs show up during the day, not at night. Morning headaches are common, caused by fluctuating oxygen and carbon dioxide levels overnight. Difficulty concentrating, irritability, and mood changes like depression frequently appear because your brain never gets the restorative deep sleep it needs.
At night, the less obvious symptoms include waking up frequently to urinate, waking with a dry mouth or sore throat, and restless sleep you may not even remember. Many people with sleep apnea don’t know they stop breathing. It’s often a bed partner who notices the gasping or the long, alarming pauses between breaths. Daytime sleepiness that persists despite what seems like a full night’s sleep is one of the strongest clues.
Who Is Most at Risk
Several physical traits increase the likelihood of obstructive sleep apnea. Neck circumference is one straightforward marker: a neck larger than 17 inches in men or 16 inches in women is a recognized risk factor, because extra tissue around the airway makes collapse more likely. Excess weight, a naturally narrow airway, a recessed jaw, and enlarged tonsils all contribute.
Men currently have a higher prevalence than women (about 46% versus 23%), but that gap is narrowing. Projections show a 65% relative increase in prevalence among women over the next few decades, compared to a 19% increase in men. Age is also a factor. The muscles that hold your airway open lose tone as you get older, which is why sleep apnea becomes more common in middle age and beyond. Alcohol, sedatives, and sleeping on your back can all worsen it.
Why It’s More Than a Sleep Problem
Every time your breathing stops, your blood oxygen drops. Your body responds with a surge of stress hormones, a spike in blood pressure, and inflammation in blood vessel walls. Repeated hundreds of times a night, this creates a pattern of intermittent oxygen deprivation, elevated stress hormones, and damage to the lining of blood vessels.
Over months and years, these nightly events contribute to high blood pressure, coronary heart disease, irregular heart rhythms, heart failure, and stroke. The relationship is causal, not just a correlation. Treating sleep apnea reduces cardiovascular risk, which is one reason diagnosis matters even if the daytime sleepiness feels manageable.
How Sleep Apnea Is Diagnosed
Doctors classify severity using the apnea-hypopnea index, or AHI, which counts how many times per hour your breathing stops or becomes dangerously shallow. Fewer than 5 events per hour is normal. Five to 14 is mild, 15 to 29 is moderate, and 30 or more is severe. Someone with severe sleep apnea may stop breathing once every two minutes throughout the night.
There are two main ways to measure this. An in-lab sleep study (polysomnography) is the more comprehensive option. You sleep overnight in a clinic while sensors track your brain waves, eye movements, heart rhythm, muscle activity, breathing effort, and blood oxygen. It captures the full picture of what’s happening during each sleep stage.
A home sleep test is simpler and more convenient. You wear a small device that monitors breathing, airflow, and oxygen levels. The trade-off is that home tests don’t measure brain waves, so they can’t tell exactly when you’re asleep versus awake. This means they estimate breathing interruptions based on total recording time rather than actual sleep time, which can sometimes undercount the severity. Home tests work well as a first step for people with a high likelihood of moderate to severe OSA, but an in-lab study may be needed if results are inconclusive or if central sleep apnea is suspected.
During a physical exam, your doctor may also look at the structures inside your mouth. The visibility of the soft palate, uvula, and the arches near your tonsils when you open wide gives a rough indication of how crowded your airway is. Less visible structures suggest a narrower airway and a higher risk of obstruction.
Treatment Options and What to Expect
CPAP (continuous positive airway pressure) remains the most effective treatment for obstructive sleep apnea. It delivers a steady stream of air through a mask you wear while sleeping, keeping your airway from collapsing. It works immediately on the first night for most people, and the improvement in sleep quality can be dramatic. The challenge is comfort. Many people find the mask, the noise, or the sensation of pressurized air difficult to tolerate, and some stop using it over time.
For people with mild to moderate OSA who can’t tolerate CPAP, oral appliances offer an alternative. These custom-fitted devices look similar to a sports mouthguard and work by pushing the lower jaw slightly forward to keep the airway open. They’re less effective than CPAP overall, but some people find they completely resolve symptoms. Oral appliances are not appropriate for severe OSA, where relying on them alone can be dangerous. They also don’t work for central sleep apnea, since the problem isn’t a physical blockage.
Lifestyle changes can make a meaningful difference, particularly for milder cases. Losing weight reduces the amount of tissue pressing on the airway. Sleeping on your side instead of your back prevents gravity from pulling the tongue and soft palate backward. Avoiding alcohol and sedatives in the hours before bed keeps throat muscles from relaxing excessively. For some people, these changes are enough to bring the AHI below the threshold for treatment. For others, they’re a useful complement to CPAP or an oral appliance.
Surgical options exist for people with specific anatomical issues, such as enlarged tonsils, a deviated septum, or an unusually small jaw. A newer approach uses an implanted device that stimulates the nerve controlling tongue movement, keeping the airway open during sleep. These are typically considered after CPAP and oral appliances have been tried.