Most people think sleep apnoea always means a blocked airway. However, that's only one type. I'm Jo Ng, a Registered Polysomnographic Technologist (RPSGT) in Singapore, and I've used CPAP myself since 2015. In this guide, I explain central and complex sleep apnoea in plain language, how they differ from the obstructive form, and why both demand proper medical care rather than guesswork.
One thing to set straight first. These conditions are diagnosed and managed by a sleep physician, not by self-adjusting a machine. Therefore, treat this as education to help you ask better questions, not as a treatment plan.
What is central sleep apnoea?
Central sleep apnoea is a breathing pause caused by a signalling failure, not a blockage. Your airway may be completely clear, yet your brain briefly stops telling your breathing muscles to work. As a result, breathing simply pauses. This differs fundamentally from the obstructive form, where the airway physically collapses.
The distinction matters because the two have different causes. In central sleep apnoea, there's no struggle against a blocked airway. Instead, the body shows no breathing effort during the pause. Consequently, these events often need a different approach from straightforward obstructive cases, which is why an accurate diagnosis comes first.
How is central different from obstructive sleep apnoea?
The core difference is mechanical versus neurological. Obstructive sleep apnoea (OSA) is a physical blockage, while central sleep apnoea (CSA) is a missed signal from the brain. OSA usually involves loud snoring and visible effort, whereas CSA shows no effort at all. Therefore, only a proper sleep study can tell them apart reliably.
| Feature | Obstructive (OSA) | Central (CSA) |
|---|---|---|
| Cause | Airway physically collapses | Brain doesn't signal breathing muscles |
| Breathing effort | Present (you struggle) | Absent (no effort) |
| Snoring | Common and often loud | Often not the main sign |
| How it's confirmed | Sleep study measuring airflow | Sleep study measuring airflow and effort |
OSA is far more common, while pure central apnoea is comparatively rare. Both, however, lower your blood oxygen and fragment your sleep. So neither is harmless, and both deserve assessment. To understand obstructive cases more fully, see my guide to succeeding with CPAP therapy.
What is complex (mixed) sleep apnoea?
Complex sleep apnoea, also called mixed sleep apnoea, is when both obstructive and central events occur in the same person. Some people have both from the start. Others develop central events only after starting pressure therapy. Therefore, complex apnoea sits between the two pure forms and needs careful, individual assessment.
Because it combines two mechanisms, it can't be reliably guessed from symptoms alone. Instead, it shows up when a sleep study measures both airflow and breathing effort across the night. Notably, this is one reason a thorough, attended study matters for some patients, rather than a basic screening alone.
Why does CPAP sometimes trigger central apnoea?
Sometimes pressure that's set too high can itself trigger central events, known as treatment-emergent central apnoea. Each person has a pressure that's "just enough" to hold the airway open. Push significantly above that, and the body can respond with central pauses. Therefore, more pressure is not automatically better.
This is precisely why pressure belongs with your provider, not with you. A setting that looks helpful for snoring could quietly create a new problem. Consequently, your provider balances "enough to open the airway" against "not so much it triggers central events." For how settings are changed clinically, see my guide on how CPAP pressure settings are adjusted.
How is central or complex apnoea diagnosed?
These conditions are confirmed through a sleep study that measures both airflow and respiratory effort. A simple airflow-only screen can miss the difference, since central events show no effort. Therefore, a more comprehensive, often attended study gives the clearest picture. Only then can a sleep physician separate obstructive from central events accurately.
This is also why I'm cautious about self-diagnosis from a smartwatch or basic home gadget. Such tools can hint at a problem, but they don't distinguish central from obstructive events. So they're a prompt to seek testing, not a substitute for it. For what testing involves, read my sleep study guide for Singapore.
How is central and complex apnoea treated?
Treatment is specialist-led and tailored to the individual. For complex cases, a sleep physician may prescribe a more advanced device than a standard CPAP, such as a bilevel (BiPAP) machine or an ASV unit. These devices manage inhale and exhale pressures differently. However, only a specialist can decide whether one suits you.
The reason is that these machines are powerful tools, not consumer settings to experiment with. An ASV device in particular is highly specialised, so its use is an individualised clinical decision. Therefore, if your case involves central events, the safest path is a sleep physician guiding the device and settings. If you'd like help understanding bilevel options, see my comparison of CPAP vs BiPAP.
What if your therapy data shows central events?
If your data shows rising central apnoeas, report it to your provider rather than adjusting anything yourself. Many machines report a Central Apnoea Index (CAI) in their data. A climbing CAI can suggest your pressure is too high for you. However, the correct response is to share that pattern with your provider, who reviews it safely.
I want to be very clear here, because this is where people get into trouble. Lowering or raising your own pressure to chase a number can backfire and create new central events. So record what you see, then hand it over. For how to read your readings properly, my walkthrough on understanding CPAP data covers leaks, AHI, and pressure together.
Can you prevent or self-manage central apnoea?
No, central and complex apnoea are not conditions to self-manage. The right pressure is a clinical target, not a comfort dial, so it needs professional setting and review. Additionally, the underlying causes can involve your heart or neurological signalling, which only a doctor can properly assess. Therefore, partnership with a sleep physician is essential.
That said, you still have a useful role. Specifically, you can attend testing, report your symptoms honestly, share your data, and stick with the plan your provider sets. In my experience, patients who do this consistently get to a stable result faster. Ultimately, your job is to observe and report, while your provider tunes the therapy.
If you suspect central or complex sleep apnoea, the next step is professional testing, not trial and error. Likewise, if your therapy data shows rising central events, raise it with someone qualified. You can reach our team via the contact page or message us on WhatsApp, and we'll help point you toward a proper sleep study and specialist care. Ultimately, getting the diagnosis right is what makes any treatment work.
Frequently asked questions
What is central sleep apnoea?
Central sleep apnoea is a breathing pause caused by a missed brain signal, not a blocked airway. Your airway can be clear, yet your brain briefly stops telling your breathing muscles to work, so breathing pauses. It differs from obstructive sleep apnoea, where the airway physically collapses. A sleep study is needed to confirm it.
What is the difference between central and obstructive sleep apnoea?
The difference is neurological versus mechanical. Obstructive sleep apnoea is a physical airway blockage, with effort and often loud snoring. Central sleep apnoea is a missed signal from the brain, with no breathing effort during the pause. Therefore, only a sleep study measuring both airflow and effort can tell them apart reliably.
What is complex sleep apnoea?
Complex sleep apnoea, also called mixed sleep apnoea, is when both obstructive and central events occur in the same person. Some people have both from the start, while others develop central events after starting pressure therapy. Because it combines two mechanisms, it needs a thorough sleep study and individual assessment by a sleep physician.
Can CPAP cause central sleep apnoea?
Yes, sometimes. Pressure set too high can trigger treatment-emergent central apnoea, because more pressure is not automatically better. Each person has a pressure that is just enough to hold the airway open. Pushing well above it can create central pauses. Therefore, your pressure should be set and reviewed by your provider, never self-adjusted.
How is central sleep apnoea treated?
Treatment is specialist-led and individual. A sleep physician may prescribe a more advanced device than standard CPAP, such as a bilevel (BiPAP) machine or a specialised ASV unit. These manage inhale and exhale pressures differently. However, only a specialist can decide whether one suits you, so this is a clinical decision rather than a self-setting.
Should I adjust my pressure if I see central apnoeas in my data?
No. A rising Central Apnoea Index can suggest your pressure is too high, but adjusting it yourself can backfire and create new events. Instead, record the pattern and report it to your provider, who can review and change settings safely. Your role is to observe and report, while your provider tunes the therapy.
