Sleep apnea is a condition where your breathing repeatedly stops and restarts during sleep. An estimated 936 million adults worldwide between ages 30 and 69 have some form of it, and roughly 26% of Americans in that age range are affected. Many people live with it for years without knowing, often because the most telling signs happen while they’re unconscious.
How Sleep Apnea Works
There are two main types, and they have different root causes. The most common by far is obstructive sleep apnea (OSA), where the physical structures in your throat collapse and block airflow. The second is central sleep apnea, where your brain temporarily stops sending the signals that tell your body to breathe. A third type, sometimes called complex sleep apnea, involves both problems at once: a physical obstruction combined with faulty breathing signals from the brain.
In obstructive sleep apnea, the soft palate (the fleshy tissue at the back of the roof of your mouth) acts almost like a one-way valve. It allows air in during inhalation easily enough, but during exhalation it can swing backward and press against the wall of the throat, narrowing or completely sealing off the airway. MRI imaging of people with the condition shows the soft palate physically making contact with the back of the throat during the exhale phase, blocking air from passing through. People whose soft palates are thicker, enlarged, or more relaxed are especially prone to this collapse.
Each time the airway closes, your blood oxygen drops. Your brain registers the emergency and jolts you just awake enough to restore muscle tone and reopen the airway, often with a gasp or snort. You typically don’t remember these micro-awakenings, but they can happen dozens or even hundreds of times per night, preventing you from reaching the deep, restorative stages of sleep.
Common Symptoms
The most recognizable sign is loud, persistent snoring, though not everyone who snores has sleep apnea. What distinguishes sleep apnea snoring is that it’s punctuated by silent pauses (the moments your airway is blocked) followed by gasps or choking sounds. A bed partner is often the first to notice these episodes.
During the day, the effects of fragmented sleep accumulate. The most common symptoms include:
- Excessive daytime sleepiness that persists even after what seemed like a full night of sleep
- Morning headaches
- Waking with a dry mouth
- Difficulty concentrating or paying attention
- Irritability
- Trouble staying asleep through the night
Because you don’t consciously experience the breathing pauses, many people attribute their daytime fatigue to stress, aging, or poor sleep habits and go years without a diagnosis.
Who Is Most at Risk
Excess weight is the single biggest risk factor for obstructive sleep apnea. Fat deposits around the neck and throat narrow the airway, making collapse more likely. A neck circumference greater than 17 inches in men or 16 inches in women is a well-established marker of increased risk, largely because it signals excess fat tissue in that area.
Other factors that raise your odds include being male, being over 40, having a naturally narrow airway or a recessed jaw, nasal congestion, smoking, and a family history of the condition. Central sleep apnea is more common in people with heart failure or who have had a stroke, since both can affect the brain’s breathing control centers.
Why It’s More Than Lost Sleep
The real danger of untreated sleep apnea goes well beyond daytime tiredness. Every time your blood oxygen drops during an apnea episode, your body mounts a stress response. Your nervous system floods with adrenaline-like hormones, your blood vessels constrict, and your blood pressure spikes. Repeated hundreds of times a night, these surges cause sustained high blood pressure that persists into daytime hours, increased arterial stiffness, and damage to the lining of blood vessels.
Over time, this cascade raises the risk of serious cardiovascular problems. The heart has to work harder against the pressure swings in the chest, which can lead to thickening of the heart muscle and eventually heart failure. Sleep apnea also pushes the blood into a more clot-prone state, with elevated levels of clotting factors and increased platelet activity. Combined with the ongoing damage to blood vessel walls, this creates conditions ripe for atherosclerosis, heart attack, and stroke.
The metabolic effects are equally concerning. The repeated drops in oxygen and sleep fragmentation trigger chronic inflammation and disrupt hormone systems that regulate appetite and blood sugar. This promotes fat accumulation and reduces the body’s sensitivity to insulin, creating a pathway toward type 2 diabetes that operates independently of weight gain alone.
How Sleep Apnea Is Diagnosed
Diagnosis hinges on measuring how often your breathing is disrupted during sleep. The key number is the apnea-hypopnea index (AHI), which counts the average number of breathing pauses or significant airflow reductions per hour. An AHI of 5 to 14 is classified as mild, 15 to 30 as moderate, and above 30 as severe.
The gold standard test is an overnight sleep study, called polysomnography, conducted in a sleep lab. Sensors track your brain waves, eye movements, muscle activity, heart rhythm, breathing effort, oxygen levels, body position, and snoring throughout the night. It’s the most comprehensive picture of what’s happening while you sleep.
For many people with suspected obstructive sleep apnea, a home sleep test is a more convenient alternative. These portable devices measure fewer signals, typically focusing on airflow, breathing effort, and oxygen saturation. They’re reasonably accurate, correctly identifying about 80 out of 100 people who have the condition, though they miss roughly 20% of cases. If a home test comes back negative but symptoms persist, a full in-lab study is usually the next step.
Treatment Options
The most effective and widely used treatment is a CPAP machine (continuous positive airway pressure). It delivers a steady stream of pressurized air through a mask you wear while sleeping. The air pressure acts as a splint, holding the airway open so the soft tissues can’t collapse. It doesn’t breathe for you; it simply keeps the passage clear so your own breathing continues uninterrupted. Most people notice a dramatic improvement in daytime alertness within the first few days of consistent use.
For people who need higher pressure settings, a BiPAP (bilevel positive airway pressure) machine is often more comfortable. It delivers higher pressure when you inhale and lower pressure when you exhale, so you’re not fighting against as much resistance on the out-breath. This tends to become the preferred option when CPAP pressure needs to reach around 15 centimeters of water pressure or higher, which can feel like exhaling against a strong wind. BiPAP is also used when central sleep apnea or low oxygen from other lung conditions is involved, since it can be set with a backup breathing rate.
Oral appliances offer an alternative for people with mild to moderate sleep apnea who can’t tolerate a CPAP machine. The most common type, a mandibular advancement device, looks similar to a sports mouthguard and works by pulling the lower jaw forward during sleep. This repositions the tongue and opens up space in the back of the throat. They’re not as effective as CPAP at restoring normal airflow, but for some people with milder cases they completely resolve symptoms. A dentist with training in sleep medicine custom-fits these devices.
Weight loss, when applicable, can significantly reduce or even eliminate obstructive sleep apnea by decreasing the fat deposits that compress the airway. Sleeping on your side rather than your back also helps, since gravity pulls the tongue and soft palate backward more in the supine position. For certain anatomical causes, surgical options exist to remove or reposition tissue in the throat, though these are typically reserved for cases where other treatments have failed.