Central Sleep Apnea: How It Differs From Obstructive Apnea

Breathing stops in central sleep apnea because the drive to breathe fades during sleep. The airway is open the whole time, and nothing is blocking it. That is what separates the condition from obstructive sleep apnea, and the difference runs through everything after it: what a sleep study records, which machine is worth a trial, and which underlying illness the assessment goes looking for.

In obstructive sleep apnea the airway itself narrows or closes, so the muscles of breathing keep working against a blockage. In central sleep apnea the airway stays open because the drive to breathe weakens, which changes what the study shows and which causes get considered, from heart failure to an opioid prescription.

If a partner has described long silences in your breathing, or you wake short of breath with no explanation, the assessment starts with the pattern on the report. Treatment has moved as well: the 2025 guideline from the American Academy of Sleep Medicine sets out which options the evidence supports, and it suggests against one approach that used to be tried.

Key takeaways

• Airflow stops with no breathing effort, because the drive to breathe falls away during sleep.
• About 0.9% of people in the community have central apnea, and it is much more common in people with heart failure, atrial fibrillation or a previous heart attack (Merck Manual Professional Edition).
• A regular waxing and waning pattern, with a cycle of about 60 to 90 seconds, points to heart failure, stroke or kidney failure (Merck Manual Professional).
• The 2025 American Academy of Sleep Medicine guideline suggests CPAP, adaptive servo-ventilation, low-flow oxygen or acetazolamide depending on the cause, and suggests against bilevel pressure that has no backup rate.
• Central apneas that appear after CPAP is started for obstructive apnea usually settle over time.

Review status: medical review pending under the practice's editorial policy. Dr. Mohammad Fawzi Katranji holds American Board certification in sleep medicine, pulmonary medicine, critical care and internal medicine, and he signs the medical review of each article.

What central sleep apnea is

Central sleep apnea is a pause in breathing during sleep that happens because the signal to breathe weakens or drops away. The airway is open, and no effort is made to breathe. A leaflet from Great Ormond Street Hospital puts it plainly: "The body does not make an attempt to breathe during these pauses."

Apnea means a pause in breathing, and central describes where the signal fails. In central apnea the fault sits in the drive that tells the chest and diaphragm to move; in obstructive apnea it sits in the airway itself. The Merck Manual Professional Edition defines central apnea as a change in ventilatory drive without airway obstruction, in contrast to the obstructive form.

The mechanism runs in two directions. In one, the drive to breathe falls and carbon dioxide rises, which the same reference links to opioids, hypothyroidism, neuromuscular disease and lesions in the brainstem. In the other, breathing overshoots during sleep, carbon dioxide drops below the level at which the brainstem keeps sending its signal, and apneas follow until it builds up again. Heart failure and a night at altitude sit behind that second pattern.

None of this means the brain is damaged. The usual explanations are a heart condition, an opioid prescription, a night at altitude or a brainstem problem. In some people no cause is found at all, and the apneas are then called primary central apnea. It is much less common than obstructive apnea.

If you have been told that your breathing pauses at night, book an appointment and bring the report with you. The pattern on it is the starting point.

Central sleep apnea vs obstructive sleep apnea

Both stop your breathing for a few seconds at a time, and both break sleep into fragments. The difference sits in what the airway and the breathing muscles are doing while the airflow stops.

A study does not only count full apneas. Many events are hypopneas, where airflow falls without stopping completely, and in those the trace alone may not show whether the airway was blocked or the drive fell away. That is one reason a report can list both kinds of event for the same person.

The labels are not exclusive. Central and obstructive events can appear in the same person on the same night, and some people develop central apneas while using CPAP for obstructive apnea, a picture called treatment-emergent central sleep apnea. In most cases those apneas resolve over time, as the Merck Manual Professional Edition notes.

The distinction changes what is tried first. A machine that holds the airway open acts on a blockage, and the 2025 guideline treats that same pressure as one option among several in central apnea. The condition behind the apneas gets its own treatment as well.

Snoring cannot settle the question either way. It can occur with central apnea, at times more quietly than a blocked airway produces, so a quiet night with long pauses still needs an assessment.

If you already have a diagnosis of obstructive apnea, obstructive sleep apnea symptoms covers the signs on that side and how that condition is tested.

Why it happens: causes and breathing patterns

The shape of the breathing on the trace often points at the cause before any other test does. A regular crescendo and decrescendo between apneas is Cheyne-Stokes respiration, and when the cycle runs about 60 to 90 seconds, the Merck Manual Professional Edition lists heart failure, stroke and kidney failure as the conditions to look for.

Heart failure is the commonest setting for that pattern, and the cycle has a visible logic. A run of deeper breaths blows off carbon dioxide, the level drops below the threshold at which the brainstem keeps signalling, and breathing pauses until carbon dioxide builds back up. A study that shows the pattern therefore sends the assessment towards the heart, and an echocardiogram is often arranged.

Stroke and other brainstem disease can interrupt the signalling pathway itself, and kidney failure sits in the same list of conditions to look for. Opioids and other sedatives matter because they depress the drive to breathe, and the medication list is one part of this you can act on with the prescriber.

Other patterns point elsewhere. Periodic breathing without the waxing and waning, over a shorter cycle, suggests primary central apnea or recent time at altitude. Breathing that is irregular and ataxic may point to opioids or other drugs.

When the drive is too low, carbon dioxide sits high, and the causes include hypothyroidism, neuromuscular disease, brainstem lesions such as infarction or encephalitis, and opioid medication including methadone. When the drive overshoots, carbon dioxide falls below the apneic threshold, the level under which the brainstem stops sending its signal to breathe, and the pause lasts until carbon dioxide recovers.

Altitude produces the same instability in healthy people, through thinner air and lower oxygen. A third picture begins after CPAP is started for obstructive apnea, when central events appear; the apneas usually fade with continued use.

Some people have no identifiable cause, and their apneas are managed as primary central apnea. Which treatment gets chosen depends on the cause more than on the event count, and the 2025 guideline says as much: treat the condition feeding the apneas, and judge success by how the person feels as well as by the number of events.

Symptoms: what you or your partner may notice

Long, quiet pauses are the usual description, and a partner usually supplies it. The pause gives way to shallow breaths and then a deeper breath or a sigh, and the sleeper may be restless through the night. Waking short of breath belongs to the same picture, and some people notice nothing at all until a study is done for another reason. What the partner reports is worth writing down while it is fresh: the length of the silence, the sound at the end of it, and how often it repeats.

Some people have no sleep complaint at all. Central apnea turns up during cardiac assessment, when someone is being investigated for heart failure or an irregular heartbeat, and the question of a sleep study often comes up there first.

Daytime signs are less specific: excessive sleepiness, lethargy, poor concentration, a morning headache and low mood. Each of them can come from many causes, and none points to central apnea on its own.

Snoring is unreliable in both directions. It can be present in central apnea, though usually at lower volume than a blocked airway produces, and a silent night does not rule the condition out.

Children need their own scale, because a certain number of pauses in breathing are normal in infants, children and young people (Great Ormond Street Hospital). The length and the number of pauses matter more than a single episode, and a parent's account of them is worth as much as any test.

Treat each of these as a pointer and write down what you notice: how long the pauses last, how often they happen, and what the breathing sounds like afterwards. That description goes into the consultation.

How it is diagnosed: what the sleep study shows

The assessment begins with the history: what you notice, what a partner notices, which medicines you take, and whether there is heart or neurological disease. Opioids and sedatives matter here, so bring the list. A medication review and an examination come before any test is booked.

Confirmation comes from a sleep study, which may be a night in a laboratory with polysomnography or a home study with portable equipment when the picture allows it. A study records airflow, the effort your chest and abdomen make, oxygen levels, heart rhythm, brain activity and video, which is how it separates an airway that closed from a signal that failed. The practice's page on what a sleep study records covers the setup and what to expect on the night.

A central event is scored when airflow stops and effort stops with it; an obstructive event shows continued effort against a closed airway. The report turns those central events into a central apnea index, the count per hour of sleep, and a mixed picture also gets a combined central apnea-hypopnea index.

The tests that follow explain the pattern. Awake arterial blood gases and bicarbonate separate the high-carbon-dioxide mechanism from the low one, and a Cheyne-Stokes pattern usually leads to an echocardiogram to look at the heart. Where carbon dioxide is high, brain or brainstem imaging may be added.

A normal study does not close the question while symptoms continue, and testing is sometimes unnecessary when the cause is obvious and reversible, such as heart failure or a recent move to altitude.

Treatment: what the options are and how they are chosen

The 2025 clinical practice guideline from the American Academy of Sleep Medicine opens with a good practice statement, and it puts the conditions behind the apneas first. Treatment should fit the clinical picture, the conditions that go with the apneas and the findings on the study, and success includes how the person feels, not only the event count. When central events persist after treatment starts, the guideline asks for the risk factors to be reviewed again.

The cause is treated first: heart failure managed properly, opioids and sedatives reviewed with the prescriber, thyroid disease or a neuromuscular condition handled on its own terms. Some people with minimal symptoms need no specific therapy at all.

CPAP is suggested over no CPAP across the main causes, at a conditional recommendation with low certainty of evidence. Bilevel pressure with a backup rate is suggested, and bilevel pressure without a backup rate is suggested against. Adaptive servo-ventilation is suggested, with shared decision-making before it starts, and the guideline limits it in heart failure with reduced ejection fraction to centres with experience, close monitoring and follow-up.

Low-flow oxygen and oral acetazolamide are suggested for central apnea due to heart failure and for central apnea at altitude. Transvenous phrenic nerve stimulation, a device placed through a vein that stimulates the nerve driving the diaphragm, is suggested for primary central apnea and for central apnea due to heart failure, with a remark that it needs an invasive procedure, is not available everywhere and carries high costs, so other options are usually considered first.

No device cures central apnea, and the certainty behind several of these recommendations is low, in places lower still. The aim is fewer events and better symptoms, checked at follow-up. If a device is chosen, CPAP and BiPAP assessment explains how pressure is set and reviewed.

Getting assessed in Dubai: no referral needed

You can ask for an assessment without a referral and without a diagnosis in hand. The practice sees adults and children, so a parent who has noticed pauses in a child's breathing books in the same way. Some consultations can happen by video when an examination is not needed, and others need a visit to the clinic.

Bring what you have: a list of medicines, any earlier sleep study report, and a partner's account of the nights. A sleep study can be arranged and read, and the result discussed in terms of the pattern, the index and the condition it points to. The practice's sleep medicine at the practice page covers the wider service, including sleep studies and CPAP care.

Breathlessness that does not settle, at rest or during the night, needs emergency care: call 998 in the UAE.

What are the treatment options for sleep apnea?

For central apnea the options are CPAP, a bilevel machine set to deliver a backup rate, adaptive servo-ventilation, low-flow oxygen and acetazolamide, with transvenous phrenic nerve stimulation for selected cases. The 2025 guideline suggests these conditionally, and the cause decides which is tried first. Bilevel pressure with no backup rate is suggested against.

What are the potential health consequences of untreated sleep apnea?

Untreated apneas break sleep into short fragments, and daytime sleepiness, lethargy and morning headaches follow. Central apnea is also common alongside heart failure, atrial fibrillation and a previous heart attack, and the guideline asks clinicians to treat the conditions contributing to the apneas, so a cardiac assessment may be arranged once the pattern is seen.

Can you have apnea while awake?

No. Apnea is defined by pauses during sleep, and wakefulness supplies extra stimuli that keep breathing steady. Awake blood gases and bicarbonate are still measured, because they show whether carbon dioxide runs high or low and which mechanism is at work. Waking short of breath is a symptom worth investigating.

If your nights include long pauses, or mornings that never feel rested, book your appointment and bring the report, the medication list and the account from the person who shares your room.