Hypopnea is a condition involving a partial reduction in breathing during sleep. Airflow does not stop completely, but drops by at least 30%, and is usually accompanied by a decrease in blood oxygen levels. It is mostly a part of sleep apnea syndrome.
Central sleep apnea is a serious breathing disorder that occurs as a result of the brain's inability to regularly transmit the "breathe" command to the respiratory muscles during sleep. Unlike obstructive sleep apnea, which is the most common form, the problem here is not the blockage of the airway, but the inadequate regulation of breathing by the brain. This condition leads to unrecognized pauses in breathing at night, a drop in blood oxygen levels, and a significant impairment in sleep quality. This clinical picture, which is seen more frequently especially in individuals with a history of cardiac and neurological diseases, can seriously affect the quality of life if not recognized early.
The symptoms of central sleep apnea often progress insidiously. Recurrent pauses in breathing throughout the night, sudden awakenings, a feeling of shortness of breath, morning headaches, excessive daytime sleepiness, lack of concentration, and fatigue are the most common complaints. Palpitations, night sweats, and difficulty concentrating may also be observed in some patients. The person is often unaware of the pauses in breathing occurring at night; it is usually the spouse or family members who notice the situation first. Therefore, symptoms should not be underestimated and professional evaluation should not be delayed.
Among the causes of central sleep apnea are factors such as heart failure, a history of stroke, neurological diseases affecting the brainstem, certain medications, and exposure to high altitude. Additionally, in a condition called complex sleep apnea, both obstructive and central mechanisms can be observed together. A sleep test (polysomnography) is of great importance for an accurate diagnosis. The type and severity of apnea are determined through a detailed evaluation, thus enabling a personalized treatment plan to be created for him.
Determining the underlying cause is essential during the treatment process. Positive airway pressure devices (especially advanced systems such as adaptive servo-ventilation), oxygen support, and medical adjustments are among the effective options. With appropriate treatment, nighttime breathing is regulated, oxygen levels are balanced, and the patient achieves a higher quality of sleep. Increased daytime energy, mental clarity, and a noticeable improvement in overall quality of life are the most important gains of correct treatment. Do not ignore symptoms to protect your sleep quality and health; early evaluation is the key to a more comfortable and healthy life.
What Is Central Sleep Apnea?
Central sleep apnea is a sleep disorder that occurs due to the temporary cessation of breathing during sleep because the brain cannot send regular signals to the muscles that control respiration.
This condition develops without any physical obstruction in the airway; the core issue is that breathing cannot be sufficiently controlled by the brain. Repeated pauses in breathing throughout the night lead to a drop in blood oxygen levels, disruption of sleep continuity, and waking up tired in the morning. Central sleep apnea, which can be particularly associated with heart diseases, neurological problems, or the use of certain medications, is a serious health problem that can be brought under control with accurate diagnosis and appropriate treatment planning.
Central sleep apnea often progresses without being noticed by the person and typically manifests with symptoms such as excessive daytime sleepiness, lack of concentration, morning headaches, and sudden awakenings at night. Short pauses in breathing during sleep can cause many organs, primarily the heart and brain, to remain deprived of oxygen. Therefore, early evaluation is of great importance, especially in individuals with heart failure, a history of stroke, or neurological disease. This condition, which can be clearly diagnosed with a sleep test, can be brought under control thanks to personalized treatment methods, ensuring a significant improvement in quality of life.
Medical Definition of Central Sleep Apnea
Central sleep apnea is a respiratory disorder of central nervous system origin, characterized by the temporary complete or partial loss of respiratory effort during sleep. In this condition, apnea episodes develop without upper airway obstruction; the fundamental pathophysiology is the inability of the respiratory centers in the brainstem to send adequate and regular impulses to the diaphragm and other respiratory muscles. In polysomnographic examination, the absence of thoracoabdominal respiratory movements together with airflow during the apnea duration is typical. Central sleep apnea is defined as a sleep-related breathing disorder that can be associated with heart failure, cerebrovascular diseases, opioid use, and certain neurological disorders, and clinically progresses with oxygen desaturation and sleep fragmentations.
Central sleep apnea is included under the heading of "sleep-related breathing disorders" in the International Classification of Sleep Disorders (ICSD), and diagnostic criteria include the detection of central apnea or hypopnea episodes above a certain number per hour on polysomnography. During these episodes, both airflow and respiratory effort are lost; meaning that thorax and abdomen movements are not observed. Pathophysiologically, mechanisms such as instability in respiratory control, changes in chemoreceptor sensitivity, and circulation delay may play a role. This clinically significant condition can be classified into primary (idiopathic) or secondary forms depending on the underlying cause and requires a detailed multidisciplinary evaluation for appropriate treatment planning.
Difference from Obstructive Sleep Apnea
The main difference between obstructive sleep apnea and central sleep apnea is the reason why breathing stops. In obstructive sleep apnea, the problem is the narrowing or complete blockage of the upper airway; the person tries to breathe, but airflow does not occur due to a mechanical barrier, while chest and abdominal movements continue during this time. In central sleep apnea, however, the airway is open, but because the brain does not send sufficient stimulation to the respiratory muscles, both airflow and respiratory effort temporarily
disappear. In other words, in the obstructive type "there is an effort to breathe but no air passes," whereas in the central type "the command to breathe is not generated." Polysomnography performed during the diagnostic process clearly distinguishes these two conditions by analyzing respiratory movements, and the treatment approach also varies according to the underlying mechanism.
Although the two conditions lead to similar complaints in terms of clinical symptoms, treatment strategies change because the underlying mechanism is different. While loud snoring and prominent airway collapse are generally at the forefront in obstructive sleep apnea, snoring may be less pronounced in central sleep apnea, and the condition is frequently associated with heart failure, neurological diseases, or certain medication uses. While the primary goal in the obstructive type is to keep the airway open, in the central type it is essential to stabilize respiratory control and treat the underlying cause. Therefore, correct differentiation is critically important for establishing an effective and personalized treatment plan.
Relationship Between Apnea and Hypopnea
Apnea and hypopnea are two core components of respiratory disorders seen during sleep and are generally evaluated together. Apnea is defined as the complete cessation of breathing for at least 10 seconds, whereas hypopnea is a marked decrease in airflow rather than a complete cut-off. In both conditions, a drop in blood oxygen levels and a disruption in sleep integrity may occur. The frequency of these events is measured by the Apnea-Hypopnea Index (AHI), and the severity of sleep apnea is determined via this total value.
Although apnea and hypopnea differ clinically from each other, their physiological effects can lead to similar outcomes. Repeated pauses in breathing or shallow breathing attacks place a burden on the cardiovascular system, cause micro-awakenings throughout the night, and lay the groundwork for complaints such as excessive daytime sleepiness, decreased attention, and fatigue. Therefore, not only complete breathing stoppages but also partial reductions carry great importance in diagnosis and treatment planning; with a comprehensive sleep test, both conditions are analyzed in detail to determine the appropriate treatment approach.
What Are the Symptoms of Central Sleep Apnea?
Symptoms of central sleep apnea often occur unnoticed throughout the night but can severely affect both nighttime sleep and daytime quality of life. The repeated stopping or irregularity of breathing causes the body not to get enough oxygen and leads to frequent awakenings. Over time, this condition can result in consequences such as chronic fatigue, attention problems, and increased cardiovascular load. The most common symptoms are:
- Repeated cessation of breathing during sleep,
- Sudden awakening and feeling of shortness of breath,
- Irregular or shallow breathing throughout the night,
- Morning headache,
- Waking up unrefreshed and chronic fatigue,
- Excessive daytime sleepiness,
- Distraction and difficulty concentrating,
- Palpitations and night sweats.
These symptoms should be evaluated more carefully, especially in individuals with a history of heart failure or neurological disease.
What Causes Central Sleep Apnea?
Central sleep apnea occurs as a result of the brain's respiratory centers failing to send regular signals to the diaphragm and other respiratory muscles during sleep. In other words, the core problem is not a blockage in the airway, but a disruption in the neurological control of breathing. This condition mostly develops due to an underlying disease or physiological imbalance and can be observed particularly in conjunction with problems related to the cardiovascular or nervous systems.
One of the most frequent causes is heart failure; the prolongation of circulation time and fluctuations in blood carbon dioxide levels can affect respiratory control. Stroke (paralysis), tumors affecting the brainstem, or neurological diseases can also disrupt the respiratory center and lead to central apnea. Additionally, certain medications such as opioid-derived painkillers can cause respiratory depression. Being at high altitude is another factor that can trigger temporary central apnea attacks. In some patients, no clear cause can be identified, and this condition is defined as idiopathic (cause unknown) central sleep apnea.
Heart Failure
Heart failure is a chronic and serious cardiovascular disease that occurs as a result of the heart's inability to pump the blood needed by the body with sufficient force. In this condition, the amount of oxygen and nutrients carried to tissues decreases, fluid accumulation may develop in the body, and organ functions are affected. The most common symptoms include shortness of breath, getting tired easily, swelling in the ankles and legs, breathing distress that increases at night, and palpitations. Especially shortness of breath increasing with exertion and difficulty breathing in a lying position at night (orthopnea) are typical findings.
Heart failure can develop due to many different causes such as high blood pressure, coronary artery disease, past heart attack, heart valve diseases, or cardiomyopathy. This disease is also closely related to central sleep apnea; the delay in circulation time and fluctuations in blood carbon dioxide levels affect the respiratory control mechanism, leading to breathing pauses during sleep. With early diagnosis, regular follow-up, and appropriate treatment, the progression of the disease can be slowed down and quality of life can be increased.
Brainstem Injury
Brainstem injury is a serious neurological condition that occurs as a result of damage to the brainstem region, which controls vital functions such as respiration, heart rate, blood pressure, and consciousness. The brainstem includes the medulla oblongata, pons, and midbrain regions and is specifically responsible for the automatic control of breathing. Injuries in this area can develop due to causes such as trauma, stroke, tumor, infection, or hemorrhage and pose a life-threatening risk.
Among the most striking findings in brainstem injury are respiratory irregularities, difficulty swallowing, speech disorders, double vision, loss of balance, and changes in consciousness. If the respiratory center is affected, central sleep apnea may develop;
because the brain cannot send regular impulses to the respiratory muscles. Diagnosis is usually made by neurological examination and imaging methods. Treatment is planned according to the cause of the damage and often requires a multidisciplinary approach.
Having a Stroke (Paralysis)
Stroke (paralysis) is a serious neurological condition requiring urgent intervention that develops as a result of the sudden interruption of blood flow to the brain or the occurrence of bleeding in a brain vessel. With the disruption of blood flow, brain cells remain oxygen-deprived, and damage can occur within minutes. The most common symptoms include sagging on one side of the face, sudden weakness or numbness in an arm or leg, speech disorders, sudden loss of vision, loss of balance, and severe headache. When these symptoms appear, applying to emergency health services without losing time is of vital importance.
Following a stroke, respiratory control may be affected in some patients, and the risk of developing central sleep apnea may increase, particularly in stroke cases involving the brainstem. When the centers in the brain that automatically regulate breathing are damaged, breathing pauses can emerge during sleep. Therefore, it is important for patients who have had a stroke to be evaluated in terms of sleep disorders alongside neurological and cardiological follow-ups. Early rehabilitation and regular follow-up support both neurological recovery and overall quality of life.
Opioid and Certain Medication Use
The use of opioids and certain medications can suppress the respiratory center and lay the groundwork for central sleep apnea. Particularly strong painkillers of the opioid derivative, such as morphine, oxycodone, and fentanyl, reduce the response of the respiratory center in the brainstem to carbon dioxide. This condition can cause breathing to slow down, become shallow, or temporarily stop completely during sleep. Central type breathing disorders are seen more frequently in individuals with long-term and high-dose opioid use.
Additionally, some tranquilizers, sedative medications, and other pharmacological agents that suppress the central nervous system can show similar effects. Especially using multiple respiratory-depressant medications together increases the risk. Therefore, sleep quality and breathing patterns must be closely monitored in patients receiving chronic pain treatment or regularly using sedative medications. Re-adjusting the medication dose when necessary or evaluating alternative treatment options holds importance in terms of respiratory safety.
High Altitude
High altitude refers to environments with lower oxygen pressure compared to sea level, and especially at elevations above 2,000 meters, the body's oxygen balance can be noticeably affected. With the decrease in atmospheric pressure, the blood oxygen level drops, and the body tries to adapt to this situation by breathing faster and deeper. However, during this adaptation process, the respiratory control mechanism can temporarily become imbalanced.
This imbalance can lead to breathing periodically accelerating and slowing down, particularly during sleep, and to short-term breathing pauses. This condition developing due to high altitude is usually temporary and improves when the individual descends to a lower altitude.
However, central sleep apnea-like breathing patterns can emerge in sensitive individuals. Therefore, it is important for individuals planning to stay at high altitudes for a long time to be cautious, especially if they have heart or lung disease, and to receive medical evaluation when necessary.
Neurological Diseases
Neurological diseases encompass a broad group of illnesses affecting the brain, spinal cord, and nervous system, which can disrupt the body's movement, sensory perception, consciousness, and autonomic functions. Particularly conditions affecting the brainstem, respiratory centers, or nerve conduction pathways can lead to irregularities in respiratory control. Parkinson's disease, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), brain tumors, and certain degenerative diseases can be evaluated within this scope. In such diseases, the disruption of nerve conduction can affect the coordination of respiratory muscles and the automatic breathing rhythm.
If the respiratory center is affected, breathing may slow down, become irregular, or temporarily stop during sleep. Therefore, symptoms such as deterioration in sleep quality, morning headaches, excessive daytime sleepiness, and breathing irregularities should be evaluated carefully in individuals with neurological diseases. Early diagnosis and multidisciplinary follow-up hold great importance both for the management of the neurological disease and for the control of potential sleep-related breathing disorders.
How Is Central Sleep Apnea Diagnosed?
The diagnosis of central sleep apnea is established through a detailed evaluation of the patient's complaints and objective sleep tests. First, symptoms such as nighttime breathing pauses, sudden awakenings, morning headaches, and excessive daytime sleepiness are inquired about; observations taken from a spouse or family members also play an important role in the diagnostic process. Underlying risk factors such as heart disease, neurological disorders, or medication use are definitely evaluated. However, a clinical history alone is not sufficient for a definitive diagnosis.
The gold standard method in diagnosis is the nighttime sleep test known as polysomnography. During this test, brain waves, respiratory movements, airflow, oxygen levels, heart rhythm, and muscle activities are recorded. In central sleep apnea, it is observed that both airflow and chest-abdomen respiratory movements stop during apnea attacks; this feature ensures it is distinguished from the obstructive type. Additional cardiac evaluations, neurological examinations, or blood tests can be performed when necessary. An accurate diagnosis is of critical importance for determining the appropriate treatment plan.
Is Central Sleep Apnea Dangerous?
Central sleep apnea is a condition that must be taken seriously, especially if it occurs together with an underlying heart or neurological disease. Repeated breathing pauses during sleep lead to a drop in blood oxygen levels and a disruption of the carbon dioxide balance. This condition can result in consequences such as heart rhythm arrhythmias, blood pressure fluctuations, and an increased burden on the heart. When left untreated in the long term, it can increase cardiovascular risks.
Nevertheless, central sleep apnea is a manageable disorder when diagnosed early and managed appropriately. The level of risk varies depending on the severity and frequency of the apnea and accompanying diseases. Closer monitoring is required particularly in individuals with heart failure, a history of stroke, or opioid use. With regular evaluation and a personalized treatment plan, both potential complications can be reduced and quality of life can be noticeably improved.
Central Sleep Apnea Treatment
Central sleep apnea treatment is primarily based on identifying the underlying cause. Because this condition frequently develops secondary to heart failure, neurological diseases, or medication use. Therefore, the treatment plan is prepared specifically for him and targets not only the breathing pauses but also the root cause. With correct evaluation, both the nighttime breathing pattern can be brought under control and long-term risks can be reduced.
One of the most frequently used methods in treatment is positive airway pressure devices. Especially CPAP, BiPAP, or in some patients, adaptive servo-ventilation (ASV) systems can be preferred. These devices help keep the oxygen level in balance by supporting respiration during sleep. In patients with heart failure, optimizing cardiological treatment, adjusting medication dosage in cases dependent on opioid use, or switching to alternative treatment may be required. Additional oxygen therapy can also be applied in some cases.
With appropriate treatment, nighttime breathing pauses decrease, sleep quality increases, and daytime fatigue improves markedly. Most importantly, the burden on the heart and brain due to oxygen fluctuations is reduced. Early diagnosis and regular follow-up are the most important factors increasing treatment success; therefore, in the presence of symptoms, undergoing an expert evaluation without delay is important.
CPAP and BiPAP Devices
CPAP and BiPAP devices are positive airway pressure respiratory support systems used to ensure that breathing continues regularly during sleep. These devices help keep the airways open and maintain adequate oxygen intake by delivering air via a mask. Especially in sleep apnea patients, they provide a more uninterrupted and higher quality sleep by reducing breathing pauses occurring throughout the night.
CPAP (Continuous Positive Airway Pressure) provides continuous airflow at a single and fixed pressure level. It is generally the first preferred treatment method in obstructive sleep apnea, but it can also be used in some central sleep apnea cases. BiPAP (Bilevel Positive Airway Pressure), on the other hand, applies two different pressure levels during inhalation and exhalation; the ability to adjust inspiratory and expiratory pressures separately provides an advantage, particularly in patients with weak respiratory effort or those with a central apnea component. Which device is appropriate is determined according to the results of the sleep test and the clinical status of the patient. Treatment efficacy can be increased markedly with the right device and correct pressure settings.
Adaptive Servo-Ventilation (ASV)
Adaptive Servo-Ventilation (ASV) is an advanced positive airway pressure support device used particularly in the treatment of central sleep apnea and mixed sleep apnea. This system analyzes the patient's breathing pattern instantaneously and makes automatic pressure adjustments according to the breathing cycle. It increases support pressure when breathing slows down or stops, and decreases pressure when breathing returns to normal. Thus, it provides a more physiological and balanced respiratory support.
ASV technology can be preferred especially in some central sleep apnea patients accompanied by heart failure; however, it is not suitable for every patient and must definitely be planned after a detailed cardiological evaluation. These devices can be an effective alternative in situations where a response cannot be obtained from classical CPAP or BiPAP treatment. With correct patient selection and appropriate pressure settings, respiratory stability can be increased throughout the night, and sleep quality can be improved noticeably.
Treatment of the Underlying Disease
One of the most crucial steps in central sleep apnea treatment is the accurate identification and effective management of the underlying disease. Because this condition frequently develops secondary to heart failure, neurological diseases, a history of stroke, or medication use. Suppressing breathing pauses solely with device treatment may not be sufficient; when the root cause is not brought under control, the problem may persist or recur.
For example, in a patient with heart failure, optimizing cardiological treatment, regulating fluid balance, and appropriate drug therapy can positively affect the breathing pattern. In cases developing due to opioid use, reducing the medication dose or evaluating alternative treatment options may be required. In neurological diseases, relevant branch follow-up and the rehabilitation process hold great importance. Effectively treating the underlying cause contributes both to the reduction of central apnea attacks and to the improvement of overall health status.
Medication Adjustment
Medication adjustment is an important step in the treatment of central sleep apnea because certain medications can suppress the respiratory center and increase apnea attacks. Particularly opioid-derived painkillers, some tranquilizers, sedatives, and medications suppressing the central nervous system can cause breathing to slow down or temporarily stop during sleep. Therefore, all medications used by the patient must be reviewed in detail.
Dose reduction can be performed under the control of the relevant physician when necessary, medication changes can be planned, or alternative treatment options can be evaluated. However, medications must definitely not be stopped on his own; sudden discontinuation can lead to serious health problems in some cases. With appropriate and controlled medication adjustment, both respiratory safety can be increased and the frequency of central sleep apnea attacks can be reduced.
Lifestyle Changes
Although lifestyle changes alone may not be sufficient in the treatment of central sleep apnea, they are important steps supporting overall health status and increasing treatment efficacy. Regulations aimed at protecting cardiovascular health, in particular, can indirectly and positively affect respiratory control. Establishing regular sleep hours, maintaining an ideal weight range, and eating a balanced diet support the body's overall physiological balance.
Limiting alcohol consumption and not using sedative medications without a doctor's recommendation are also important because these substances can suppress the respiratory center. Regular physical activity can contribute to nighttime respiratory stability by increasing cardiovascular capacity. Additionally, since sleeping on the back can increase breathing irregularities in some patients, appropriate position recommendations can also be evaluated. These changes help achieve more effective results when applied together with medical or device treatments.
Central Sleep Apnea vs. Obstructive Sleep Apnea
Although both central sleep apnea and obstructive sleep apnea are characterized by the repeated impairment of breathing during sleep, their formation mechanisms differ. In obstructive sleep apnea, the core problem is the narrowing or complete closure of the upper airway; the person tries to breathe, but airflow does not occur because the airway is closed. In central sleep apnea, however, the airway is open, but the brain does not send sufficient signals to the respiratory muscles; therefore, both airflow and respiratory effort temporarily stop.
In terms of symptoms, the two conditions can lead to similar complaints of excessive daytime sleepiness, morning headaches, and attention problems. However, while loud snoring is generally prominent in the obstructive type, snoring may be less pronounced in the central type and is frequently associated with heart failure or neurological diseases. Diagnosis is clarified with polysomnography, and the treatment approach is planned according to the underlying mechanism. Therefore, making the correct distinction is of great importance for effective and personalized treatment.
The Difference Between Them
| Comparison Criterion | Central Sleep Apnea | Obstructive Sleep Apnea |
| Cause of Formation | Failure of the brain's respiratory center to send sufficient signals | Narrowing or blockage of the upper airway |
|
Airway Status | Open | Partially or completely closed |
| Respiratory Effort | Absent during apnea | Present during apnea |
| Snoring | Generally not prominent | Mostly loud |
| Comparison Criterion | Central Sleep Apnea | Obstructive Sleep Apnea |
|
Most Common Risk Factors | Heart failure, neurological diseases, opioid use | Obesity, anatomical airway narrowing |
| Diagnosis | Detection of central apnea via polysomnography | Detection of obstructive apnea via polysomnography |
| Treatment Approach | Treatment of the underlying disease, BiPAP or ASV | CPAP, weight control, surgery in some cases |
Who Develops Central Sleep Apnea?
Central sleep apnea is seen more frequently in specific risk groups in the population and is generally associated with an underlying health problem. It occurs most often in patients with heart failure; particularly in individuals with advanced heart disease, the respiratory control mechanism becomes more sensitive. Furthermore, in individuals who have had a stroke (paralysis), the risk of developing central apnea increases, especially if there are lesions affecting the brainstem.
Individuals with neurological diseases are also at risk. Conditions affecting the nervous system, such as Parkinson's disease, multiple sclerosis (MS), and ALS, can disrupt the automatic control of breathing. In addition to this, the respiratory center can be suppressed in individuals using long-term opioid (morphine derivative) painkillers, and central apnea attacks can be observed.
Temporary central sleep apnea can also develop in individuals living at high altitudes or those who suddenly ascend to high elevations. Moreover, advanced age, male gender, and the presence of severe chronic disease can be counted among factors increasing the risk. In some cases, no clear cause can be identified, and this condition is evaluated as idiopathic (cause unknown) central sleep apnea.
In summary, it is important to perform a careful evaluation regarding central sleep apnea, especially in individuals with heart, brain, and nervous system diseases, as well as those using medications affecting the respiratory center. Early diagnosis plays a critical role in preventing potential complications.