Complex Sleep Apnea: Symptoms, Causes, Diagnosis & Treatments

There are three primary categories of sleep apnea, the most prevalent of which is obstructive sleep apnea (OSA), which is most effectively treated with a sleep device. The other two forms are complex sleep apnea and central sleep apnea.

Complex sleep apnea is being diagnosed at an accelerating rate as researchers and medical professionals learn about the condition and the factors that contribute to its development. Central sleep apnea, however, is still relatively uncommon.

Complex sleep apnea is essentially a mix of central and obstructive symptoms. It occurs when the patient does not experience a remission of symptoms after therapy with either CPAP or an oral appliance. Even when they are utilizing a CPAP, patients who have complex sleep apnea will usually still have episodes of the condition.

The condition known as sleep apnea might be difficult to grasp. Regrettably, even some doctors and other medical professionals sometimes get the definitions of certain diagnoses wrong. This may result in tests and treatments that are not essential, resulting in additional expenses.

It is critical to have a thorough understanding of the symptoms and indications that are associated with a specific diagnosis, namely complex sleep apnea. What does it mean to have complex sleep apnea, also referred to as treatment-emergent sleep apnea?

Find out more about this ailment, including its symptoms and what causes it, as well as how it is diagnosed, the most effective therapies for it, and whether or not therapy is even required.

Complex Sleep Apnea

Complex Sleep Apnea

Complex sleep apnea is also known as treatment-emergent central sleep apnea. It happens when a person with a history of obstructive sleep apnea acquires central sleep apnea due to being treated with continuous positive airway pressure (CPAP).

Unpacking all of this will take some time, so let’s start with the definitions.

First, obstructive sleep apnea happens when the upper airway (or throat) closes while the patient is sleeping. This can cause reductions in the oxygen levels in the blood and awakenings or arousals from sleep.

This disorder is considered to be present when a diagnostic sleep study known as a polysomnogram reveals that five or more obstructive episodes are happening per hour of sleep. There are a few other names for these types of airway collapses, including obstructive apneas, mixed apneas, hypopneas, and respiratory-related arousals.

Continuous positive airway pressure (CPAP) therapy is by far the most frequent and successful treatment option once obstructive sleep apnea has been diagnosed. A face mask is worn during this therapy, through which a steady stream of air is delivered.

This increased air prevents the airway from contracting or being blocked, which in turn stops snoring from occurring. However, in some people, this might cause alterations in their breathing that lead to a condition known as central sleep apnea, which is when they hold their breath while sleeping.

When CPAP therapy is used to treat sleep apnea, this condition is considered to be complex sleep apnea. When treatment is administered, obstructive episodes go away, but central apnea events either arise or continue to exist.

These central apnea events must occur at least five times each hour, and they should account for more than fifty percent of the overall number of apnea and hypopnea occurrences. You do not have complicated sleep apnea if, throughout the course of your CPAP therapy, you experience 100 apneic episodes, and only 49 (or perhaps even less) of them are due to central apnea.

It is fairly usual for certain instances of central apnea to arise, although it is possible that they do not require any more action beyond the passage of time.

Causes Of Complex Sleep Apnea

There is still a mystery about the root causes of complex sleep apnea. There might be a lot of factors that led to the disease, and not all of them are associated with the CPAP treatment.

Certain people may be more likely to develop the illness because they have less control over their breathing than others. People who have trouble falling or staying asleep, such as those with insomnia, may have a higher risk of developing this condition. It appears to be precipitated by low carbon dioxide levels in other individuals.

If a person has more severe sleep apnea in the beginning (with a greater apnea-hypopnea index, six or AHI), or if they have more central apnea occurrences detected before therapy, this may increase their risk. Additionally, it appears to be more common among males.

It is important to note that the likelihood of developing complex sleep apnea seems to be increased by various sleep apnea therapies.

There have been reports of central sleep apnea being brought on by both surgical procedures and the use of oral appliances. It is also possible for this to occur if the PAP therapy’s pressure settings are either too high or, on the other hand, too low, whether this is established during a titration study or during later home usage.

Symptoms Of Complex Sleep Apnea

Symptoms Of Complex Sleep Apnea

Complex Sleep Apnea usually begins with Obstructive sleep apnea, so the symptoms are almost similar. It is essentially a mix of both central and obstructive symptoms. It occurs when the patient does not experience a remission of symptoms after therapy with either CPAP or an oral appliance. Even when they are using a CPAP, patients who have complex sleep apnea will frequently still have episodes of the condition.

The following are some symptoms that may be associated with sleep apnea:

  • Daytime tiredness and drowsiness
  • Insomnia
  • Trouble concentrating and paying attention 
  • Issues with memory 
  • Anxiety
  • Irritability
  • Headaches
  • Difficulty executing tasks

Diagnosis Of Complex Sleep Apnea

Your doctor may conduct an assessment based on your indications and symptoms and a history of your sleeping patterns, which you may offer to your doctor with the assistance of someone who shares your bed or your home.

You should expect to be referred to a facility that focuses on the treatment of various sleep disorders. At that location, a sleep expert will be able to aid you in assessing whether or not you need more tests.

Monitoring your breathing and other bodily processes as you sleep for a whole night at a sleep center is typically required during an examination. However, there is also the option of carrying out sleep evaluations at home. Tests such as the following can be used to diagnose sleep apnea:


During this test, you will be linked up to several pieces of machinery that will monitor your heart rate, breathing patterns, arm and limb movements, and blood oxygen levels while you are sleeping.

Home Sleep Testing

Home Sleep Testing

To accurately diagnose sleep apnea, your doctor may provide you with some simpler tests that you may perform at home. During these examinations, your heart rate, blood oxygen level, airflow, and breathing patterns are often measured.

Your physician may be able to prescribe a treatment for you even if additional testing is not necessary if the results are abnormal. Portable monitoring equipment does not identify all types of sleep apnea; however, even if your first findings are benign, your doctor may still prescribe polysomnography as a precautionary measure.

Suppose you have been diagnosed with obstructive sleep apnea. In that case, your primary care physician may suggest that you see a specialist in ear, nose, and throat conditions in order to rule out the possibility of a blockage in either your nose or throat. To investigate potential causes of central sleep apnea, a patient would need to undergo testing with a cardiologist or a neurologist.

Treatment Of Complex Sleep Apnea

Treatment Of Complex Sleep Apnea

Even while most people recover from complex sleep apnea over time, there is still a subset of individuals (around 2% of the population) in whom the illness remains, and there may be further repercussions. Some of these individuals may need other therapies in order to get rid of the illness.

Likely, complex sleep apnea will still be present even after the periodic download of PAP compliance statistics. During the first three months of usage, this will often occur at a follow-up consultation routinely scheduled with your sleep expert.

Adjustments may need to be made if more than five episodes of central apnea occur in one hour, even though episodes of obstructive sleep apnea have stopped occurring. Why could this possibly be important?

Persistent sleep fragmentation and oxygen desaturation may result from complex sleep apnea, which a high residual AHI often accompanies. This might result in daytime tiredness and other negative health impacts in the long run.

However, this may also affect PAP therapy since the user may not report experiencing many benefits from the treatment and may have trouble adhering to it over the long run.

It is quite necessary to take into consideration the probability of change from one night to the next. In the context of your starting condition, you may be able to tolerate some increases in the AHI as long as the overall response to therapy is satisfactory.

Although the devices can offer an approximate measurement of central apnea occurrences, they are not ideal, and it is possible that this would be better analyzed using a regular polysomnogram.

It is possible that treating the underlying reasons will be necessary in order to cure complex sleep apnea. For instance, if the pressures that are being utilized are simply excessive (or, much less frequently, inadequate), a specific change could be enough to rectify the situation. Likewise, if you wake up because your mask is leaking, getting it properly fitted might be helpful.

In some circumstances, it may be essential to move to adaptive servo-ventilation (ASV) treatment or bilevel servo-ventilation (ST), which involves a timed breath rate provided during breath pauses. In order to determine the best settings for the device, a titration study is frequently necessary for these types of treatment modalities.

The wisest therapy is typically the one that is most effective: time. Keeping up with treatment for complex sleep apnea will often result in an improvement in 98 percent of patients. It is possible that it will not be necessary to take any additional action other than waiting and seeing how the remaining events resolve themselves independently.


A person is said to have complex sleep apnea if they do not react completely to CPAP therapy and continue to have apnea episodes during sleep, although their airway is now more open.

The underlying cause is frequently neurological, and it cannot be remedied by any of the treatments that are now available. It is also possible for people to acquire complex sleep apnea after utilizing the continuous positive airway pressure (CPAP) machine or an oral appliance for an initial diagnosis of obstructive sleep apnea (OSA).

Most of the time, this issue will clear itself on its own over time and as you continue to use your appliance. However, research is currently being done to determine the characteristics that put people at risk for complicated sleep and what causes it.

Sarah Wagner

I'm Sarah Wagner, and I founded Sweet Island Dreams in 2022. It's a blog dedicated to helping people mental vacation virtually anytime they want. By providing information about the best sleep of your life, I help people drift away to paradise without ever having to leave their bed!

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