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While sleep apnea is becoming a term that is more and more familiar among people in the United States, it’s less common that people realize that there are actually two main types of sleep apnea. Though obstructive sleep apnea (OSA) is much more common, central sleep apnea (CSA) is also an important condition to be aware of.
In both OSA and CSA, a person suffers from apneas — temporary halts in breathing — during the night. These apneas can be very disruptive to sleep and can pose more serious health issues. However, the causes and treatments for these two types of sleep apnea are quite different.
In this guide, we’ll introduce you to the key information about central sleep apnea, including an explanation of what it is and how it is different from OSA. We’ll also cover its causes, symptoms, health risks, diagnosis, and treatment so that you can be informed about this particular type of sleep apnea.
What Is Central Sleep Apnea?
CSA is much less common than OSA. When someone refers to “sleep apnea” without specifying a type, they are usually referring to OSA.
CSA happens because the brain does not effectively send messages to the muscles that control breathing at night. In particular, CSA occurs because of a problem in the brain stem, which controls breathing. Normally, the brain stem manages our breathing — such as promoting more rapid or slower breathing — based on the concentration of carbon dioxide in the blood. But in people with CSA, the brain stem struggles at effectively performing this function, causing breathing to become shallower and prone to halting apneas.
While CSA is a condition relating to the brain and how it controls breathing, OSA, on the other hand, happens because of a physical blockage of the airway. This blockage makes it difficult for air to pass, leading to loud snoring and apneas.
It is possible for someone to have both CSA and OSA at the same time, and this is known as complex sleep apnea.
What Are the Symptoms of Central Sleep Apnea?
Apneas and interrupted breathing are the most obvious symptoms of central sleep apnea. For this reason, CSA is often first noticed by a partner who observes this shallow and halted breathing.
Some symptoms of CSA are similar to OSA. For example, the two conditions may share the following symptoms:
- Abnormal breathing when sleeping: breathing can slow significantly and may pause or halt for up to a minute. At times, breathing may sound very shallow or like a person is gasping or choking while sleeping.
- Difficulty sleeping: apneas can cause a person to wake up in the night, and for some people this can make it harder to fall back asleep. This interrupted sleep can also erode overall sleep quality.
- Dry mouth and throat: shallow breathing and gasping can lead to issues with dryness or soreness in the mouth and throat.
- Morning headaches: people with both OSA and CSA often find that they have painful and consistent morning headaches.
- Pronounced daytime sleepiness: given the abundance of sleep disruptions from apneas, many people with CSA and OSA find that they are extremely sleepy during the day. This ultimately can interrupt work and social functions.
- Fatigue: a broader lack of energy and a feeling of a lack of strength can both be symptoms of both types of sleep apnea.
- Cognitive problems: as a result of reduced sleep duration and quality, people with sleep apnea may struggle to remember things, to maintain their attention span, or to have their normal level of focus. They may have mood changes such as being easily frustrated, irritable, anxious, or depressed.
- Raised blood pressure: poor breathing while sleeping can cause oxygen levels in the blood to fall and can even lead to a subsequent increase in blood pressure.
While CSA and OSA share many symptoms, it is important to note one symptom that is not normally shared: snoring. Snoring is one of the most common symptoms of OSA because of the actual physical obstruction of the airway. But in CSA, snoring is not nearly as common or as pronounced even when it does occur.
As CSA is caused by improper functioning of the brain stem, sometimes it happens at the same time as other nervous system issues. For this reason, other symptoms may appear along with CSA that can be an indication of this type of problem. Some examples of these types of symptoms are difficulty swallowing, numbness in much of the body or throughout the body, and changes to a person’s voice.
What Are the Causes of Central Sleep Apnea?
There are multiple potential causes of CSA. Some of these causes include:
- Use of sedatives and narcotic pain medications: these types of drugs can affect the performance of the brain stem, especially if their use is prolonged. People who have chronic pain and regularly take opioids may be at heightened risk of CSA.
- Heart failure or stroke: these can cause a type of CSA called Cheyne-Stokes breathing. This is marked by a gradual increase and then decrease in the rate of breathing.
- High altitude: living at a higher altitude can put a person at an elevated risk of developing CSA.
- Injury or condition of central nervous system: an injury or other health issue that affects the brain, particularly the brain stem, can cause CSA. One example is a brain tumor, but it is important to know that this is a rare cause of CSA.
In some situations, there is no clear explanation for why a person has CSA. This is referred to as idiopathic CSA.
For OSA, obesity is a main risk factor, but for CSA, there is limited evidence that obesity contributes to a person’s risk.
What Are the Health Risks of Central Sleep Apnea?
There can be major health risks associated with CSA. Some of these risks stem from the lack of sleep that can come with CSA. For example, everyday obligations and responsibilities, ranging from workplace roles to family and social life, can be difficult to manage without adequate sleep. Excessive sleepiness during the day also raises the risk of personal injury from accidents, falls, or car crashes.
Cardiovascular implications, such as atrial fibrillation and raised blood pressure, are also potential consequences from the reduced level of oxygen in the blood that occurs when breathing during sleep is impaired.
How Is Central Sleep Apnea Diagnosed?
The usual process for diagnosing CSA starts with a visit to a doctor or nurse. During this visit, a health history is taken, and a physical examination is performed. The health history may also involve asking questions of a partner or other family who have observed breathing disruptions in the past.
In many cases, a sleep study is used to diagnose CSA. This is called polysomnography and is very often done in a specialty sleep clinic where you spend the night and you are carefully monitored. This testing can help reveal the amount of oxygen that you are getting and the nature of your apneas. Results from sleep testing of this type are usually available within a few days. A sleep technician or your doctor may review the results with you.
If CSA is diagnosed, other tests may be necessary to try to identify any underlying health conditions that may be causing it. For example, a CT scan or MRI of the brain may be necessary to check for any damage or conditions that could be affecting breathing.
If there is a more direct or obvious cause, such as from the regular use of opioid medications, sleep testing or other types of medical tests may not be necessary unless CSA persists after modifying the patient’s medications to reduce reliance on opioids or sedatives.
How Is Central Sleep Apnea Treated?
If the doctors are able to determine that CSA is being caused by another health condition, then resolving that condition is the first line of therapy. This could include management of heart failure or brain issues or ending the use of pain medications or sedatives.
There are some other therapies that may be used to treat CSA and can be similar to those used for OSA:
- Supplemental oxygen: this involves providing extra oxygen to help ensure that a person’s blood oxygen levels do not fall too low.
- CPAP therapy: CPAP stands for continuous positive airway pressure, and CPAP machines pump pressurized air into the airway to keep it open while you are sleeping. The CPAP machine delivers this air through a hose and into the mouth and airway. This requires the use of a mask over the course of the whole night. For some people, wearing this mask is too uncomfortable and itself disrupts sleep. Most people, though, get used to using a CPAP mask and machine.
- BIPAP therapy: similar to CPAP therapy, BiPAP therapy uses a machine to pump pressurized air into the airway through a hose and a mask. The difference is in how the pressure is regulated. In a CPAP machine, the air pressure is the same when a person inhales and exhales, but in a BiPAP, it’s different. This is why BiPAP stands for bi-level positive airway pressure and CPAP is continuous positive airway pressure.
- Adaptive servo-ventilation (ASV) therapy: ASV is like CPAP and BiPAP in that it delivers pressurized air, but it is different because it can adjust the level of pressure for each individual breath. If CSA is caused by heart failure, ASV is not considered to be a treatment option.
- Provent: Provent is an FDA-approved therapy for OSA that does not have as much use with CSA. It is a small device that is placed in the nostrils with a valve in the center of the device. The valves help maintain pressure in the airway to help keep the airway open. These devices are small and disposable and avoid the noise and mask associated with CPAP and BiPAP. While this is a proven therapy for OSA, it has not been demonstrated in clinical trials to be a treatment for CSA.
- Surgery: though not common, one possible surgical option is placing a nerve stimulator near the diaphragm to promote breathing.
While there are treatments that can be effective, there is limited evidence from randomized, controlled clinical trials or research studies about the optimal treatment for CSA. As a result, treatment may not be standardized, and it may be necessary to try different treatment options to help resolve CSA or reduce the severity of its symptoms.
Take a look at our reviews for CPAP and BiPAP machines below to learn more about these devices.
What Medications Are Available for Central Sleep Apnea?
Medical therapy for CSA is very limited. Some patients may receive drugs that help with attention or wakefulness in order to reduce the symptoms of daytime fatigue and sleepiness. An example of a drug that can be used this way is modafinil.
If CSA is caused by high altitude, the drug acetazolamide is often effective. This drug is used for multiple conditions including managing altitude sickness.
It is necessary for anyone with CSA or excessive sleepiness to talk with a doctor or other health professional before beginning to use any medication.