What Is Central Sleep Apnea and How It Differs from Obstructive Sleep Apnea

Central sleep apnea is a condition where breathing repeatedly stops during sleep. It is less common than obstructive sleep apnea and is often misunderstood. The two conditions share some symptoms but have different causes and require different treatments. Understanding the difference is essential for getting the right diagnosis.

In obstructive sleep apnea, the airway physically collapses during sleep. Soft tissue at the back of the throat relaxes and blocks the flow of air. The body keeps trying to breathe but cannot get air through. In central sleep apnea, the airway stays open. The problem is in the brain. The brain temporarily stops sending the signal that tells the breathing muscles to work. There is no effort to breathe at all during these episodes.

This distinction matters because the treatments are different. What works for one condition may not work for the other, and in some cases the wrong treatment can make things worse.

Central sleep apnea accounts for roughly 5 to 10 percent of all sleep apnea cases. It affects men more often than women and becomes more common with age. It is also more prevalent in people with certain medical conditions including heart failure, stroke, and kidney disease.

Causes of Central Sleep Apnea

Central sleep apnea has several distinct causes depending on the type.

Idiopathic central sleep apnea has no identifiable underlying cause. The brain simply fails to regulate breathing consistently during sleep, for reasons that are not fully understood. This is the most basic form of the condition.

Heart failure is the most common medical cause. When the heart cannot pump blood efficiently, fluid can build up and the body's control of breathing becomes unstable. This produces a characteristic pattern called Cheyne-Stokes breathing, where breathing gradually increases, then decreases, then stops, in a repeating cycle.

Stroke and neurological conditions can damage the brain regions responsible for sending breathing signals. This includes conditions like Parkinson's disease and multiple system atrophy.

Medications, particularly opioid pain medications, can suppress the brain's respiratory drive. Opioid-induced central sleep apnea is a recognized and growing clinical problem.

High altitude can trigger central apneas in some people due to lower oxygen levels in the air, though this form typically resolves when returning to lower elevations.

Treatment-emergent central sleep apnea occurs in some people when they start CPAP therapy for obstructive sleep apnea. The obstructive events resolve but central apneas appear. This is also called complex sleep apnea syndrome. It often resolves over time with continued treatment.

Symptoms of Central Sleep Apnea

Central sleep apnea symptoms overlap significantly with obstructive sleep apnea, which is one reason it is often diagnosed only after a formal sleep study.

The most common symptoms include frequent awakenings during the night, often with shortness of breath or the sensation of not being able to breathe. Unlike obstructive sleep apnea, loud snoring is less common with central sleep apnea, though it can still occur. Many people with CSA are light sleepers who wake easily and have difficulty returning to sleep.

Daytime consequences are similar to obstructive sleep apnea. People with untreated CSA commonly experience excessive daytime sleepiness, difficulty concentrating, memory problems, and mood changes. Morning headaches can occur as a result of fluctuating oxygen and carbon dioxide levels during the night.

A bed partner may notice episodes where the person stops breathing during sleep. Unlike obstructive apnea, these pauses are typically silent rather than accompanied by loud gasping or snoring.

How Central Sleep Apnea Is Diagnosed

A sleep study is required to diagnose central sleep apnea. The standard test is polysomnography, an overnight study conducted in a sleep laboratory. The test monitors brain activity, heart rate, breathing effort, oxygen levels, and body position throughout the night.

The key diagnostic measure is the apnea-hypopnea index, or AHI, which counts the number of breathing pauses per hour of sleep. The study also distinguishes between obstructive events, where breathing effort continues but airflow stops, and central events, where both breathing effort and airflow stop simultaneously. This distinction is what separates a diagnosis of CSA from OSA.

Home sleep tests are widely used for obstructive sleep apnea but are generally not recommended for central sleep apnea. They do not measure the respiratory effort signals needed to distinguish central from obstructive events. A full in-lab study is usually required.

Central Sleep Apnea vs Obstructive Sleep Apnea

The cause of obstructive sleep apnea is a physical blockage in the airway. The cause of central sleep apnea is a failure of the brain's breathing signal. Obstructive sleep apnea commonly produces loud snoring. Central sleep apnea often does not. Both cause repeated nighttime awakenings and daytime sleepiness. Obstructive sleep apnea is treated primarily with CPAP. Central sleep apnea requires different devices or approaches depending on the underlying cause.

One of the most important practical differences is treatment response. CPAP is highly effective for obstructive sleep apnea. For central sleep apnea, standard CPAP may be insufficient or inappropriate. Some patients with CSA are made worse by CPAP because the steady pressure can disrupt the brain's already-unstable breathing rhythm.

Treatment Options for Central Sleep Apnea

Treatment depends on the underlying cause. Identifying and addressing the root condition, when one exists, is always the first step.

For CSA caused by heart failure, optimizing cardiac treatment often improves the sleep apnea. For opioid-induced CSA, reducing or changing pain medication may help. For high-altitude CSA, descending to lower elevation resolves the problem.

When a specific cause cannot be addressed or the CSA is idiopathic, positive airway pressure therapy is the main treatment approach, though different devices are used than for obstructive sleep apnea.

Adaptive servo-ventilation, or ASV, is the most targeted therapy for CSA. It monitors the patient's breathing in real time and delivers pressure to smooth out irregular patterns, backing up breathing when the brain fails to signal. It is considered more effective than standard CPAP or BiPAP for most forms of CSA. However, ASV is contraindicated for patients with heart failure and reduced ejection fraction, an important distinction that a sleep specialist must evaluate before prescribing.

Bilevel positive airway pressure, or BiPAP, with a backup respiratory rate can provide a minimum breathing rate for patients who stop breathing. It is used when ASV is not appropriate.

Supplemental oxygen is sometimes used alongside positive airway pressure therapy, particularly in patients with heart failure or other conditions that reduce blood oxygen levels.

Acetazolamide is a medication that stimulates breathing by altering blood chemistry. It is sometimes prescribed for high-altitude CSA and occasionally for other forms.

Treatment for central sleep apnea is more complex and individualized than for obstructive sleep apnea. Working with a sleep specialist who has experience with CSA is important.

When to See a Doctor

Anyone who regularly wakes up gasping or struggling to breathe, feels excessively sleepy despite enough time in bed, or has been told by a bed partner that they stop breathing during sleep should see a doctor. These symptoms can indicate either obstructive or central sleep apnea, and only a sleep study can determine which one.

People with heart failure, a history of stroke, or who use opioid medications are at elevated risk for central sleep apnea and should discuss screening with their physician even without obvious symptoms.