Sleep apnea syndrome falls into three types, based on what’s actually causing the breathing to stop.
Each type has a slightly different cause and a slightly different treatment approach, which is why classifying it correctly matters.
Kazuyuki Sugaya
Director, Ueno Snoring Clinic / Anesthesiologist
Our director, with over 20,000 general anesthesia cases, focuses primarily on the diagnosis and treatment of snoring and sleep apnea, offering care tailored to each patient. [Insurance-Covered] Ueno Snoring Clinic
This article was reviewed by our Director, Kazuyuki Sugaya, and explains accurate medical information about the testing and treatment of snoring and sleep apnea syndrome (SAS) in clear, accessible terms.
The causes of snoring range from the structure of the throat to body weight. Ueno Snoring Clinic doesn’t rely on a single treatment approach — we’re set up to recommend the best plan for each patient from a broad, evidence-based range of options.
Insurance-Covered: Thorough Testing and Ongoing Treatment
Self-Pay: Address the Root Cause, Short-Term Focus
*As a clinic specializing in snoring treatment, we work to resolve “snoring that won’t stop” through both insurance-covered and self-pay options.
Quick Answer
Sleep apnea syndrome falls into three types based on what’s actually causing the breathing to stop: obstructive (OSA), where the airway physically collapses and which accounts for more than 90% of cases; central (CSA), where the brain’s respiratory control center fails to send the signal to breathe, often linked to heart failure, stroke, certain medications, or high altitude; and mixed, which combines both patterns and can be especially difficult to diagnose and treat. Because treatment differs meaningfully by type — starting standard CPAP for what’s actually a central or mixed pattern can sometimes make things worse rather than better — getting an accurate diagnosis through proper sleep testing matters more than the label “sleep apnea” alone.
📋 What This Article Covers
This is by far the most common type, accounting for more than 90% of cases. It happens when the upper airway — the passage air travels through — particularly the pharynx at the back of the throat, physically collapses during sleep, causing breathing to stop again and again. This pattern shows up in the vast majority of sleep apnea cases, with more than 90% classified as obstructive.
A defining feature is that the person is still trying to breathe, but no air actually gets through. The chest and abdomen keep moving — meaning the physical effort to breathe continues — even though the airway itself is blocked and oxygen can’t get in.
As a result, blood oxygen levels drop, and the brain senses the effective suffocation and forces a brief awakening in order to restart breathing. This “waking up” is often something the person has no memory of at all — in reality, apneas lasting anywhere from a few seconds to over ten seconds can repeat dozens, sometimes over a hundred times, in a single night. Without realizing it, the person ends up in a state where they should be asleep, but aren’t actually getting any real rest.
Breathing stops because the airway at the back of the throat — the pharynx — becomes physically blocked.
A simple analogy makes this easier to picture: imagine trying to drink through a straw that’s been pinched flat between your fingers — no matter how hard you suck, no air or liquid gets through. In OSA, the airway acts like that pinched straw, physically collapsed shut.
Making things worse, when this cycle repeats over and over, the entire rhythm of sleep gets fragmented — the body spends the whole night cycling through suffocation, waking, breathing resuming, and apnea again.
In a very real sense, it’s a quiet battle being fought where no one else can see it.
This type occurs when a malfunction in the brain’s respiratory control center causes breathing to stop. It’s more common in people with a history of heart failure or stroke. Unlike OSA, the airway isn’t blocked at all — breathing stops simply because the brain fails to send the signal to breathe.
Specifically, the neural activity in the brainstem and medulla that controls the breathing muscles temporarily halts, so no signal reaches the chest or diaphragm telling them to move.
In other words, unlike OSA — where the throat is physically blocked and air can’t get through — CSA involves no physical airway obstruction whatsoever. Breathing itself simply stops, due to a more central, neurological cause.
There are several known causes of CSA, broadly grouped as follows.
In patients with heart failure, where the heart’s pumping function is reduced, a mismatch develops between blood flow and the respiratory control center, destabilizing the mechanism that regulates breathing timing and triggering CSA. This type of CSA often shows a pattern called Cheyne-Stokes breathing, where breaths alternate between shallow and deep — and it can also be a sign of worsening heart failure overnight.
Damage to the brainstem or medulla can impair the nerves that control breathing itself, sometimes resulting in CSA.
Long-term use of opioid pain medications in particular — such as morphine or fentanyl — is known to suppress the respiratory control center and can trigger CSA.
In low-oxygen environments such as high mountain regions, the respiratory control center can become either overstimulated or suppressed, leading to periodic fluctuations in breathing — a form of central apnea sometimes called “high-altitude CSA.” This is usually temporary.
It’s not an exaggeration to say this is a state where, overnight, the body essentially “forgets” to even try to breathe. Since the respiratory muscles aren’t working at all and there’s no airflow whatsoever, this type of apnea is often silent — with no snoring audible to people nearby — which makes it especially easy to miss.
This type involves a combination of both OSA and CSA. A defining feature of mixed apnea is that it starts as a quiet apnea, and then the body gradually begins struggling to resume breathing.
Watching a patient with mixed apnea sleep, a distinct pattern often emerges: it begins in complete silence — not even snoring — and then breathing sounds gradually return, often accompanied by louder snoring and body movements as the person struggles to breathe.
This “silence → struggle → snoring resumes” sequence is the classic signature of mixed apnea.
Diagnosing mixed apnea is only possible through a thorough, overnight sleep study (polysomnography, or PSG). By using sensors to track respiratory effort — the movement of the chest and abdomen — clinicians can determine whether that effort is present, pointing to an obstructive component, or absent, pointing to a central one.
In particular, if a patient reports being unable to sleep, or feeling “off,” after starting CPAP therapy, mixed apnea should be strongly suspected. That’s because treatment aimed at OSA can sometimes unmask an underlying central component, making overall treatment less effective — or even counterproductive.
For these reasons, mixed sleep apnea can be genuinely difficult to diagnose.
The key lies in re-selecting the right form of respiratory support.
Simple CPAP therapy is often not enough for mixed sleep apnea. In particular, when the central component is significant, more advanced respiratory support options are considered, such as the following.
ASV is a state-of-the-art ventilation device that analyzes a patient’s breathing pattern in real time and automatically adjusts pressure and ventilation as needed. A major advantage is that it can address both central (CSA) and obstructive (OSA) sleep apnea. That said, it can be contraindicated in patients with certain forms of heart failure, so a careful evaluation of cardiac function is needed before starting it.
Bilevel NIPPV supports breathing by applying different pressure levels during inhalation and exhalation. In mixed apnea cases where the obstructive component is more prominent, it can help by assisting inhalation while reducing the effort needed to exhale. It tends to work well for patients whose mixed apnea leans more toward the OSA side.
Mixed sleep apnea comes with three particular challenges:
Because of this, diagnosis and ongoing monitoring by a specialist experienced in sleep medicine are essential.
It’s also important to maintain both device tolerability and quality of life. For each patient, the type of device, pressure settings, and mask shape need to be carefully adjusted and optimized over the long term.
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We provide medical services for international patients. Please check our English website for details on how to visit our clinic.
Supervising Physician
Kazuyuki Sugaya, Director of Ueno Snoring Clinic
After graduating from Fujita Health University School of Medicine in 2004, Dr. Sugaya began his career as an anesthesiologist at Toho University Omori Medical Center. He has since gained extensive clinical experience at municipal hospitals and private clinics nationwide, administering general anesthesia in over 20,000 cases. In 2020, he founded the "Tokyo Spine Clinic," and has served as the Director of Ueno Snoring Clinic since 2025.
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