Alaska Sleep Education Center

The 3 Types of Sleep Apnea Explained: Obstructive, Central, & Mixed

Posted by Jennifer Hines

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on Jul 13, 2018 4:04:00 AM

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Sleep apnea is a very common sleep disorder, affecting roughly 20 million Americans. Sleep apnea is a condition in which a person stops breathing periodically during sleep. These cessations in breathing can occur anywhere from a few times a night up to hundreds of times a night.

When a person stops breathing in their sleep, they are partially awakened from sleep as their brain is forced out of deeper stages of sleep to get the body to begin breathing again. When this occurs several times an hour, quality sleep decreases, and a whole slew of medical problems can begin to arise.

While many people may be familiar with the most prevalent form of sleep apnea, obstructive sleep apnea, it often goes unrecognized that there are other types of apneas that a person may be suffering from. Here we aim to shed light on all three of the types of sleep apnea and discuss the symptoms, prevalence, causes, and treatments of each.

What is Obstructive Sleep Apnea?

Obstructive sleep apnea (OSA) is the most common form of sleep apnea and is believed to affect approximately 4% of men and 2% of women. However, it is believed that only about 10% of people with OSA seek treatment leaving the majority of OSA sufferers undiagnosed.


OSA illustrationObstructive sleep apnea is caused by a partial or complete blockage of the airways during sleep. During sleep, a person's throat muscles relax allowing the tongue and/or fatty tissues of the throat to fall back into the airways and block airflow.

During an apnea, event air is restricted from moving beyond the obstruction reducing blood flow to the brain. This in turn signals the brain to partially awaken from sleep to signal the body that it needs to breathe.

This is often followed by loud gasping, choking, or snorting sounds as the person takes a deep enough breath to fight past the obstruction.


Once a breath is taken the brain returns to sleep, and the process begins once again. This process can occur just a few times a night or hundreds of times a night depending on the severity of the condition.

  • Mild OSA- The sufferer experiences 5-14 episodes of interruptions in breathing in an hour.

  • Moderate OSA- The sufferer experiences 15-30 episodes of interruptions in breathing in an hour.

  • Severe OSA- The sufferer experiences 30 or more interruptions in breathing in an hour.

Other symptoms of obstructive sleep apnea include:

  • Snoring that is loud, disruptive, and regular is one of the most obvious signs of potential OSA. 

  • Frequent breaks in breathing caused by an obstruction. These cessations are often followed by choking or gasping noises as the body's respiratory system fights through the blockage.

  • Excessive daytime sleepiness is caused by frequent interruptions of sleep.

  • Morning Headaches stem from the loss of oxygen in your bloodstream that flows to your brain as a result of irregular breathing at night.

  • Restless sleep. Sufferers of obstructive sleep apnea often have fitful sleep as their minds and body are constantly awakened throughout the night, pulling them out of the much-needed stages of non-REM and REM sleep. 

  • Depression or irritability. Lack of regular quality sleep can wreak havoc on a person's mental well-being. Sufferers of obstructive sleep apnea often find themselves feeling short-tempered, and in time it can lead to more severe symptoms of depression.

Causes and Risk Factors

  • Weight- In many cases, a person's body weight is directly linked to having obstructive sleep apnea. People who are overweight or obese are more likely to have sleep apnea than those that maintain a healthy weight.

    Sleep apnea can often be caused by excess fatty tissues that become built up in the neck and throat. This can lead to restrictions in airflow as the upper respiratory system's pathway is narrowed or pinched off during sleep.

  • Age- As people age, their muscles begin to lose muscle tone. This is also true of the muscles in the throat. As throat muscles lose definition, they become weaker and more likely to collapse into the airways during sleep.

  • Enlarged tonsils or adenoids are the leading cause of obstructive sleep apnea in children but can also affect adults who never had a tonsillectomy when they were younger.

  • Natural causes- Some people can be genetically predisposed to having a narrower throat or may have an enlarged tongue that falls back into their airway. If your family has a history of OSA you are more likely to have it yourself.

  • Frequent alcohol use- Alcohol relaxes the muscles in the body, and this includes the throat muscles as well which may relax to the point of blocking the airway during sleep.

  • Smoking- Smoke is an irritant to the lungs, throat, and esophagus. It can cause inflammation and fluid retention in the upper airways that can impede airflow.


sleep apnea CPAP machinePositive airway pressure (PAP) Therapy

Oral Appliances

  • Mandibular advancement devices (MADs)

  • Tongue retaining mouthpieces


  • Uvulopalatopharyngoplasty (UPPP)
  • Adenotonsillectomy

  • Nasal Surgery

  • Maxillomandibular Advancement (MMA)

What is Central Sleep Apnea?

Central sleep apnea (CSA) occurs when the brain temporarily fails to signal the muscles responsible for controlling breathing. Unlike obstructive sleep apnea, which can be thought of as a mechanical problem, central sleep apnea is more of a communication problem.

Central sleep apnea is also much less common than obstructive sleep apnea. Some estimates claim that approximately 20% of sleep apnea cases are CSA, but many others believe that number to be much lower (Source).

Central sleep apnea is often caused by medical problems and conditions that affect the brainstem. These different causes often lead to varying symptoms and different types of central sleep apnea.


  • Alaska-sleep-apnea150Stopping breathing or irregular breathing during sleep

  • Shortness of breath leading to awakenings

  • Excessive daytime drowsiness

  • Chronic Fatigue (turmeric supplements may be able to help with this)

  • Morning headaches

  • Poor/Restless Sleep

  • Difficulty concentrating

  • Mood changes

  • Snoring (snoring isn't as prevalent as it is in OSA sufferers)

Causes or conditions that can lead to CSA

  • Parkinson's disease

  • Medical conditions that affect the brain stem including brain infection and stroke

  • Obesity

  • Certain medications like narcotic painkillers

  • Heart failure

Risk Factors

  • Men are more likely to develop CSA than women

  • More common among older adults, especially those over 65

  • People with heart disorders such as atrial fibrillation and congestive heart failure are at greater risk

  • People who have had a stroke or have a brain tumor

  • People sleeping at higher altitudes than they're accustomed to. Symptoms usually go away after returning to regular altitude

  • People who use opioid medications are at greater risk

  • Some people with obstructive sleep apnea can develop central sleep apnea when they're being treated with positive airway pressure (PAP) devices.


  • Treating existing conditions that are causing CSA is often the first line in treatment options for the disorder.

  • happycpapcoupleContinuous positive airway pressure (CPAP). Similar to OSA, one of the first treatment options for CSA is the use of CPAP therapy. A CPAP device includes a breathing mask that sleep apnea sufferers wear when sleeping. Just enough consistent air pressure is delivered via the mask to the patient's airways to keep the tissue that otherwise would collapse (and cause breathing pauses and snoring) from closing during sleep. CPAP devices are effective in treating sleep apnea but do not cure the disorder. If you discontinue using your CPAP device, your sleep apnea may return.

  • Bilevel positive airway pressure (BPAP). Bilevel positive airway pressure is similar to CPAP except that BPAP adjusts the level of air being delivered depending on whether the patient is inhaling or exhaling. During inhalation, an electronic sensor tells the BPAP to send more air through the mask to clear the apnea-causing obstruction. When the user exhales, the air pressure is reduced. This decrease is helpful for sleep apnea sufferers who have a rough time breathing out against the constant pressure of a CPAP machine.

  • Adaptive-servo ventilation (ASV). The Adaptive-servo ventilation device monitors breathing and adjusts airflow appropriately through the mask to match how the patient would be normally breathing if awake. This adjustment can be made quickly as soon as the ASV detects that the patient is not breathing correctly (as is the case with central sleep apnea, when the brain doesn’t signal the body to take a breath). When the patient exhales or after the patient resumes a normal breathing pattern, ASV adjusts the pressure again.

  • Medications. Certain medications, such as acetazolamide (Diamox) or theophylline (Theo-24, Theochron, others), have been used to stimulate breathing in people with central sleep apnea. Medications may be prescribed when positive airway pressure therapy fails to be efficient.
  • Phrenic Nerve Stimulation

    Phrenic Nerve Stimulation is a new FDA-approved therapy for moderate to severe central sleep apnea in adult patients.  Phrenic nerve stimulation is delivered by a pacemaker-like implantable device that stimulates a nerve in the chest (phrenic nerve) to send signals to the diaphragm to control breathing.  It monitors respiratory signals while you sleep and helps restore normal breathing patterns. Because the device is implantable and turns on automatically during sleep, it does not require wearing a mask.


    Phrenic nerve stimulation allows normal breathing to resume by stabilizing carbon dioxide, preventing apneic events, and the subsequent period of rapid breathing.


What is Mixed Sleep Apnea? AKA Complex Sleep Apnea

Mixed sleep apnea is a combination of both obstructive and central sleep apnea symptoms. Some patients being treated for obstructive sleep apnea with the use of CPAP machines develop symptoms of central sleep apnea upon PAP therapy. This phenomenon had long been noticed in sleep labs but had not been previously researched. In 2006 researchers from the Mayo Clinic conducted a study of 223 sleep apnea patients and found that 15% of sleep apnea patients who were believed to have OSA in fact had mixed sleep apnea. (source)

During CPAP treatment for the patients believed to have OSA, the patient's airways were successfully splinted open and free from obstructions, but the patient continued to have difficulty breathing while asleep. Their symptoms of OSA shifted to symptoms of CSA while CPAP therapy was being administered.


Optimal treatment options for mixed sleep apnea still need to be refined. Currently, one of the best treatments is still CPAP devices but set at the lowest possible pressure setting that successfully keep the airways free from obstructions, but doesn't allow CSA symptoms to develop.

In some cases where CPAP fails, BiPAP machines and adaptive servo-ventilation devices are then tried which can better control ventilation (source). Bilevel positive airway pressure devices are able to deliver pressurized air that can resolve the obstructive component as well as stabilize ventilation during central apneas by forcing breaths (timed breath) during episodes of central apneas.

Adaptive servo ventilators have shown successful use as the machines are capable of performing a breath-to-breath analysis and altering their settings accordingly.

However, while both BiPAP and ASV machines have shown improvement in therapy over CPAP machines for mixed sleep apnea there is still no best treatment for Mixed sleep apnea.

What to do Next

If you're an Alaskan resident and you believe that you may have symptoms of sleep apnea, click the link below to schedule a free 10-minute phone consultation with one of our clinical sleep specialists. In just 10 minutes we can help you discover whether or not your symptoms warrant a sleep study to help you get diagnosed and treated for your sleep disorder.

Chronic Drowsiness

Topics: sleep apnea, sleep disorders

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