Are you someone who regularly wakes up feeling as though you didn’t get a wink of sleep? If you have ever discussed this issue with your doctor, they likely mentioned sleep apnea as a potential cause. After all, it is one of the most widely diagnosed sleep disorders, with an estimated number of cases reaching over one billion.
While the majority of these individuals struggle to breathe at night due to airway obstruction (OSA), a small percentage of cases are attributed to a lesser-known issue called Central Sleep Apnea (CSA). Unfortunately, because it only accounts for 5-10% of all sleep apnea diagnoses, many people are unaware of what this condition is, nor what this type of diagnosis actually means.
If you or a loved one suspects that they may have CSA or have been recently diagnosed, we want to provide you with in-depth information that you can rely on as you determine your next steps. So, in today’s guide, we will be taking a deeper look into this condition.
We’ll explain how CSA impacts breathing and identify its many causes and symptoms. Additionally, we’ll go over some of the most common types, along with how this form of sleep apnea is diagnosed and treated. We will also discuss the health risks associated with having CSA, along with some risk factors and prevention tips. Lastly, we’ll talk about how this condition impacts your well-being, plus provide some suggestions to help you sleep better despite sleep apnea.
What is Central Sleep Apnea?
As the name suggests, CSA is a type of sleep-related breathing disorder that is characterized by changes in breathing at night. Unlike Obstructive Sleep Apnea, which is caused by structural changes within the airway, this condition stems from a neurological issue. As a result, the brain struggles to communicate with the muscles that are involved in the process of respiration, such as the diaphragm. This leads to repeated episodes in which the amount of oxygen in the blood falls below safe levels.
People with this form of sleep apnea often experience repeated episodes in which their breathing stops and restarts. However, unlike with its obstructive counterpart, people with CSA are less likely to report loud snoring. The two most common complaints of people with this form of sleep apnea are that they wake up in the middle of the night feeling as though they can’t catch their breath, and as a result of these wakeups, they also feel as though they can never get enough sleep at night. Because of this, some people with CSA say that they feel perpetually tired and rundown.
Mechanisms Behind Central Sleep Apnea
CSA can be triggered by many things, but at its core, this form of sleep apnea occurs due to an underlying issue with the nervous system. This is because your body’s respiratory system functions based off of directions from the brain.
Breathing with Normal Brain Function
Breathing is usually said to be an involuntary process, meaning you don’t have to actually tell yourself to breathe, and you don’t have to “decide” to move your diaphragm like you would an arm or leg. This is why people say that it is impossible to hold your breath until you die. Because when you pass out, you will automatically resume breathing like normal, despite being unconscious.
If your neurological system is functioning normally, your brain stem analyzes the amount of oxygen and carbon dioxide in your blood and sets your breathing rate accordingly. During sleep, the brain is particularly sensitive to carbon dioxide and becomes triggered after a certain amount is allowed to build up in the blood. This level is called the apneic threshold, and once it is reached, the brain responds by sending signals to the muscles that are involved in breathing. As a result, these muscles (including the diaphragm) begin to contract, which allows the rib cage to make extra room as the lungs begin to expand and take in air.
Because the brain is so sensitive to chemical changes in the blood, it can also sense when carbon dioxide levels are too low. When this occurs, the brain sends signals to slow the respiratory rate. In response, breathing becomes slower and more shallow.
In addition to this system, you also have the option to voluntarily regulate your breathing when you are awake. This message comes from a different part of the brain from that of the involuntary system. It is this process that allows you to take control of your breathing patterns when you are speaking or swimming. This ability to consciously choose when and how to breathe goes away when you are asleep, which is one reason why people become more susceptible to CSA when they are sleeping.
Breathing with CSA
In the case of Central Sleep Apnea, there is an issue with the brain’s carbon dioxide detection system and/or the communication between the brain and the muscles in and around the rib cage. In the event that it is a communication problem, the issue can originate from either end, meaning either the brain struggles to send out a signal or the muscles become less responsive to the signals being sent.
Regardless of the cause, the outcome is the same— the muscles involved in breathing fail to constrict at the necessary times, resulting in the lungs being unable to take in a breath. For those who have CSA, this means that their breathing often becomes slow and shallow or may even stop altogether while they are asleep.
In mild cases, respiration may only pause for a short period of time before the body is able to resume normal breathing on its own. If these episodes go on for too long or occur too frequently, your brain may respond by triggering something called the arousal response. During this process, the brain sends out a frantic message that it is running low on oxygen, which stimulates you to abruptly wake up and take in a big breath of air. If these types of episodes occur multiple times a night, they can begin to have a major impact on both your sleep health and general well-being.
In some cases, these issues involve an increase in carbon dioxide in the body. This form of CSA is referred to as “hypercapnic,” which means “too much carbon dioxide.” It can be triggered when the brain becomes less sensitive to carbon dioxide levels. This can cause the brain to delay sending out the signals that it is time to take in a new breath of air. As a result, the brain allows too much carbon dioxide to build up in the body before finally telling you to take a breath. This problem is further complicated by the fact that you are unable to consciously stimulate breathing, as you would when you are awake.
Additionally, there are other reasons that carbon dioxide may build up in the blood. Usually, this is due to some sort of condition that affects your ability to exhale fully. Regardless of the cause, this increase in carbon dioxide levels in the blood can ultimately further affect breathing, sometimes to the point that it becomes so shallow that it stops altogether.
Hypercapnic apnea is typically caused by:
- Neurological disorders
- Conditions that cause slow breathing
- Chronic respiratory conditions
- Taking narcotic medications
It is also possible for there to be an issue that is not related to an increase in carbon dioxide levels. This is called non-hypercapnic sleep apnea, and it can be triggered by the brain sensing that the levels of carbon dioxide are actually too low. When this occurs, it delay’s the brain’s ability to sense that it is low on oxygen. As a result, the brain once again delays sending out the signal that it is time to breathe.
This form of CSA can also develop as a result of the brain being simply unable to send signals to the respiratory system. Additionally, sometimes it is caused due to a problem with the muscles themselves. In such cases, the muscles are either unable to sense the signals being delivered from the brain or are too weak to carry out their necessary functions.
Non-hypercapnic CSA is usually caused by:
- Heart failure
- Neuromuscular diseases
- Exposure to high altitudes
- Other conditions that trigger hyperventilation
Causes of Central Sleep Apnea
Over the decades, scientists have extensively studied the respiratory system, including how it is impacted by sleep apnea. Recently there has been a lot of research into why Central Sleep Apnea occurs and how it impacts the body. However, we still don’t fully understand what causes Central Sleep Apnea to develop in one person over another. Currently, each case is categorized based on whether or not it has been triggered by an underlying condition.
The first category is primary CSA, although it is sometimes referred to as “idiopathic”. This simply means that it has no identifiable cause. For a person with sleep apnea to fall into this category, there can be no underlying reason for this condition to arise. In other words, these cases stem solely from some sort of functional issue within the brain. This form of sleep apnea is relatively rare, and scientists continue to study how and why it occurs.
In the case of secondary CSA, there is an underlying diagnosis that has contributed to the development of sleep apnea. This category is far more common compared to its counterpart, with the majority of cases being linked to some sort of identifiable trigger. Such conditions typically impact the brain, muscles, carbon dioxide and oxygen concentrations in the blood, and/or all of the above.
The following list includes some of the most widely recognized underlying causes of secondary CSA.
- Opioid Use: These drugs are known for having an impact on the respiratory system. Specifically, they suppress the brain’s ability to sense changes in the oxygen and carbon dioxide levels in the blood. They also impact its ability to tell your muscles that they need to constrict so that the ribcage and lungs can expand.
- Neuromuscular Diseases: As the name suggests, neuromuscular diseases affect the function of the nerves and muscles in the body. Muscles that are impacted by neuromuscular disease are unable to effectively receive and respond to signals from the brain. Additionally, they are more likely to be weakened by such conditions, meaning in some cases, even if they do receive a signal from the brain, they may be unable to function at the necessary capacity.
- Central Nervous System Conditions: Similar to neuromuscular diseases, central nervous system conditions indicate an issue with the function of the nervous system itself. Some of these conditions directly impact brain function, including its ability to sense chemical changes in the blood, while other conditions may cause damage to the nerves through which the brain’s signals are sent.
- Stroke: Stroke events often lead to at least some form of brain damage. When that damage occurs in the right area(s), it can impact the brain’s ability to effectively govern the respiratory process.
- Heart Failure: Heart failure can impact breathing in two ways. First, it causes a decrease in the amount of oxygen in the blood, which in turn triggers hyperventilation. As a result, the amount of carbon dioxide in the blood decreases. This causes the brain to delay sending out the signal to take a breath. In severe cases, heart failure can lead to less oxygen getting to the brain, which can trigger communication issues between the brain and the respiratory muscles.
- High Altitude: The air that exists at high altitudes contains less oxygen than that in lower altitudes. This can lead to hyperventilation, which causes a decrease in the amount of carbon dioxide in the blood. In response to this process, the breathing rate may slow significantly.
Symptoms of Central Sleep Apnea
Unlike Obstructive Sleep Apnea, CSA can oftentimes be more difficult to identify because its signs tend to be less obvious compared to the loud snoring that usually accompanies OSA.
In fact, people with this condition tend to have similar complaints to those who experience poor sleep quality for a variety of other reasons. This is because the defining characteristic of this form of sleep apnea is that it triggers your body to regularly rouse itself from sleep, sometimes numerous times in a single night. As a result, people with CSA often wake up feeling as though they never went to bed.
If this sounds familiar, there is one particular sign that suggests a high probability of having at least one form of sleep apnea— that is, regularly waking up with the sensation that you are choking or gasping for air. Additionally, if you sleep with a partner, they may report that you have a tendency to display abnormal breathing patterns as you sleep. Of course, these can also be signs of OSA. However, if they are present without excessively loud snoring, these may be more likely to indicate the presence of Central Sleep Apnea.
Below are the most common signs and symptoms of CSA:
- Slow and/or shallow breathing
- Waking up gasping for air
- Difficulty staying asleep
- Feeling restless at night
- Excessive daytime sleepiness
- Morning headaches
- Mood changes
- Cognitive changes
- Snoring (less common and less extreme than the snoring that is caused by airway obstruction)
Types of Central Sleep Apnea
The following are some of the most common types of CSA. While some are caused by underlying issues, others may be temporary and may even resolve themselves in the right circumstances.
- Cheyne-Stokes Respirations Central Sleep Apnea: CSR-CSA occurs as a result of the brain being unable to regulate the breathing process during sleep. It is characterized by clusters of rapid, shallow breathing before a series of slower, deeper breaths. These are followed by a short period of extremely shallow breathing or no respiration at all. Each cycle lasts between 40 and 90 seconds. This condition is often seen in people who have had a stroke or are living with heart failure.
- Non-Cheyne-Stokes Respirations/Medical Condition-Induced Central Sleep Apnea: As mentioned above, CSA can be triggered by all kinds of medical conditions. While some of these, such as heart failure, can lead to Cheyne-Stokes Respirations, others have been linked to a form of Central Sleep Apnea that results in a different type of breathing pattern. These cases are referred to as Non-Cheyne-Stokes Respirations or Medical Condition-Induced CSA.
- High Altitude-Induced Periodic Breathing: This form of sleep apnea is often compared to CSR-CSA, as it involves a similar respiration pattern. However, it is triggered by an increase in altitude and occurs even in healthy people who are positioned at least 6,000 feet above sea level. It is caused by the decrease in the amount of oxygen that is found in the air at high altitudes.
- Narcotic-Induced Central Apnea: Narcotics are known for suppressing the central nervous system. People who take these drugs in high doses display slow, shallow breathing. In some cases, breathing may even stop altogether. This is because narcotics decrease the brain’s sensitivity to changes in the levels of carbon dioxide in the brain. Additionally, they suppress communication between the brain and the respiratory muscles.
- Idiopathic Central Sleep Apnea: This condition is often referred to as “primary CSA.” It occurs when this form of sleep apnea develops without any identifiable cause. It is believed to originate as an issue with the brain itself.
- Complex Sleep Apnea: Sometimes CSA can arise in response to current treatment for obstructive sleep apnea. While the reason for complex sleep apnea is not fully understood, it is believed that when a person receives positively pressurized air directly into their airways, it may impact the way that the brain senses oxygen and carbon dioxide levels in the blood. This condition is thought to be more common in people who have underlying health conditions such as heart failure.
Diagnosing Central Sleep Apnea
If you experience regular pauses in your breathing each night and suspect that you have sleep apnea of any kind, your doctor will likely perform a physical exam before suggesting that you complete a polysomnogram, also known as a sleep study.
This test involves monitoring your body movements, brain waves, and vital signs as you sleep in order to determine whether you are experiencing periods of reduced (hypopnea) or paused breathing (apnea). In order to be diagnosed with Central Sleep Apnea, your sleep test must result in:
- At least five episodes of apnea or hypopnea per hour
- Each episode lasting more than ten seconds
- Displaying and/or complaining of at least one common sign of sleep apnea
If it seems as though you are experiencing regular periods of apnea or hypopnea, your doctor may choose to perform additional tests to rule out other potential causes and to identify any underlying triggers before officially diagnosing you with CSA.
Identifying Various Types of CSA
Your doctor may look for the following factors when determining which category of sleep apnea you fall under.
- Primary CSA: Requires you to show at least one common sign of sleep apnea, plus at least five periods of central apnea or hypopnea per hour, without any evidence of Cheyne-Stokes breathing.
- Cheyne-Stokes Respirations CSA: This form of sleep apnea involves the same criteria as primary CSA. However, it also requires you to have three or more episodes of central apnea or hypopnea in a row, with periods of Cheyne-Stokes Breathing in between each one.
- Complex CSA: Also known as treatment-emergent CSA, this diagnosis requires you to have a current diagnosis of OSA and be undergoing treatment via some sort of Positive Airway Pressure device.
Treatment for Central Sleep Apnea
While some forms of Central Sleep Apnea can resolve on their own over time, such as high-altitude and narcotic-induced cases, others require treatment. If you have been diagnosed with CSA, your doctor will choose a treatment plan based on whether your condition has been triggered by any underlying causes.
Treatment options usually include some combination of the following:
- Supplemental Oxygen
- Positive Airway Pressure (PAP) devices
- Lifestyle Changes
In the event that you have secondary CSA, your doctor will most likely suggest addressing the issue that has caused you to experience sleep apnea. This may also involve medications or simple lifestyle changes. If your condition is serious, you may be provided additional breathing support to reduce your risk of experiencing health complications caused by these periods of apnea or hypopnea.
The most common method of respiratory support in people with sleep apnea is Positive Airway Pressure (PAP) devices. PAP machines deliver pressurized air through the airway and into the lungs, which helps to regulate the breathing cycle. If you are diagnosed with sleep apnea, your doctor will likely have you try one of the following types of PAP machines.
- Continuous Positive Airway Pressure Device: Most of the time, people with CSA tend to start out with a Continuous Positive Airway Pressure (CPAP) machine, which produces a continuous flow of pressurized air into the lungs. This level of pressure is maintained constantly unless changed manually by a specialist.
- Bi-Level Positive Airway Pressure Device: If you have an underlying condition that makes breathing particularly difficult, your doctor may instead suggest a BiPAP machine. This device utilized two pressure settings, providing highly pressurized air during inhalation but reducing the amount of air pressure during exhalation. This helps reduce the amount of effort needed to exhale. This is particularly helpful if your condition has been triggered by some sort of respiratory system issue, such as COPD.
- Adaptive Servo-Ventilation Device: An ASV machine is similar to BiPAP in that it is often a better fit if you have an underlying condition that affects your ability to breathe even when awake. Rather than using two predetermined settings, as with BiPAP, this device measures your breathing patterns and adjusts the air pressure accordingly.
Health Risks Associated with Central Sleep Apnea
When you experience pauses in your breathing, even for short periods of time, it can start to take a toll on your long-term health and well-being. People who have sleep apnea have been documented as having reduced antioxidant activity and increased inflammation. Additionally, sleep apnea has been associated with many chronic conditions when it is left untreated. Thankfully, current research suggests that these effects are likely reversible when treatment is sought.
Risk Factors for Central Sleep Apnea
There are several factors that have been linked to an increased likelihood of developing this form of sleep apnea. These include:
- Heart Disease: Having heart failure or even heart disease can cause you to have a substantially higher risk for CSA, as it can lead to less oxygen getting to the brain and can trigger your body to hyperventilate.
- History of Stroke: According to the National Library of Medicine, half of all people who have had a stroke end up developing some form of sleep apnea. This is likely a direct result of the brain damage that is caused by the stroke itself.
- Brain Tumors: Tumors can interfere with the brain’s ability to carry out certain functions, depending on their location. In some cases, they can interfere with the brain’s ability to sense chemical changes in the blood or send out messages to the respiratory muscles.
- Exposure to High Altitudes: When you are at a high altitude, this can trigger changes in the oxygen and carbon dioxide levels in the blood.
- Use of Narcotics: Narcotics are known for causing respiratory depression.
- Being Treated for Obstructive Sleep Apnea: While the cause is unknown, Complex Sleep Apnea occurs as a result of being treated for OSA. According to one large study, 6.5% of participants who were being treated for OSA also developed Central Sleep Apnea.
- Being Male: Studies suggest that men are at a greater risk for developing CSA. This may, in part, be due to the fact that they are also at a higher risk for other conditions which can trigger this form of sleep apnea. Experts believe that testosterone levels may also play a role in a person’s likelihood of experiencing this issue.
- Age: This form of sleep apnea is thought to be most common in people who are at least middle-aged. However, Cheyne-Stokes Respiration CSA is seen more often in older populations, specifically 60 years old or more.
- Obesity: Being overweight can trigger a condition called Obesity Hypoventilation Syndrome, which can trigger CSA. While the cause of this condition is not fully understood, it is believed that it may be related to the strain that is placed on the respiratory muscles due to being surrounded by excess fat.
Preventing Central Sleep Apnea
Because Central Sleep Apnea is most often caused by another health complication, the best way to prevent this condition is to prevent and/or address other underlying medical issues. You can limit your risk for CSA and other triggering conditions by doing the following:
- Maintain a healthy weight.
- Choose healthy foods.
- Get regular exercise.
- Avoid smoking.
- Reduce alcohol intake
- Limit the use of narcotic drugs.
- Avoid taking sedative medications when possible.
- Avoid traveling to places located at high altitudes.
- Seek treatment for underlying conditions when they arise.
Living with Central Sleep Apnea
Without treatment, central sleep apnea can impact your physical, mental, and emotional well-being. Untreated sleep apnea has been proven to increase your risks for other life-altering medical conditions, including diabetes and heart disease. And the experience of repeatedly waking up to catch your breath each night, even if you are not always consciously aware of it, can leave you feeling as though you are permanently exhausted. Eventually, this has an impact on your brain’s ability to function at its full potential and may leave you struggling with mood changes and cognitive issues.
Overcoming these effects often involves implementing some pretty big lifestyle adjustments, including the foods you eat, the medications you take, and potentially even the places you live and/or visit (in the case of high-altitude CSA). If you suspect that you may have this form of sleep apnea, it’s important to remember that the best way to manage this condition is to seek out the advice of your healthcare provider so that you can come up with a treatment and management plan that suits your individual needs best.
Tips for Getting Better Sleep with CSA
Here are a few suggestions for how a person with CSA can improve their sleep quality:
- Follow a treatment protocol.
- Sleep on your side.
- Avoid taking sedatives.
- Limit alcohol intake before bed.
- Sleep at an incline.
- Communicate any issues or concerns with your doctor.
Frequently Asked Questions (FAQs)
What Is the Difference Between Central Sleep Apnea and Obstructive Sleep Apnea?
While Central Sleep Apnea and Obstructive Sleep Apnea share many similar signs and symptoms and are even associated with many of the same risk factors, they have two very different causes. As the name suggests, obstructive apnea deals with an obstruction of the airway, which is caused by the soft tissue in the neck and throat areas.
However, CSA involves an issue within the brain and/or respiratory muscles. In such cases, either the brain is unable to sense and/or respond to changes in the amount of carbon dioxide in the blood, or there is a communication issue between the brain and the muscles that are involved in breathing, such as the diaphragm. Regardless of the exact cause, the outcome is that these muscles are unable to constrict so that breathing can take place.
Can Central Sleep Apnea be Cured?
This depends on why you have sleep apnea. Primary CSA is not entirely understood and may require treatment for your entire life. In secondary cases, your condition may be reversible, depending on the underlying cause. And some cases are temporary by definition, such as those that are narcotic or high altitude-induced. Even in the event that your sleep apnea cannot be cured, most cases can be treated and well managed with breathing support and lifestyle management.
Is Central Sleep Apnea Life-Threatening?
Yes, there are a few dangerous effects of Central Sleep Apnea, which can threaten your life, just as any other condition that affects your breathing. In some cases, the apnea can become so severe that your body is unable to resume breathing on its own. However, CSA can also trigger other health issues, which may also endanger your well-being. For example, sleep apnea is known to increase your risk of stroke or heart conditions.
If you are someone who finds yourself waking up in the middle of the night because you feel as though you’ve been holding your breath, you may be living with an undiagnosed form of sleep-breathing disorder called Central Sleep Apnea. Although this condition is much less common than its counterpart, Obstructive Sleep Apnea, it can be very serious if left untreated.
It is characterized by the brain’s inability to effectively communicate with the respiratory muscles, which often results in breathing becoming very shallow or even pausing altogether. These episodes tend to be short-lived, but they can have a big impact on your health and well-being, especially if they become a common occurrence.
People living with this form of sleep apnea often struggle with feeling as though they can never get enough rest and may even begin to see changes in their mental function or emotional state. Thankfully, these effects can be improved with respiratory support and lifestyle changes.
If you suspect that you may be living with sleep apnea, it is important to speak with your provider regarding your concerns. Your doctor will likely suggest a sleep study to determine whether you are experiencing breathing changes as you sleep.