OVERVIEW

What is sleep apnea syndrome?

Sleep apnea syndrome is a sleep-related breathing disorder. Normally, during sleep, air flows rhythmically through the nose and/or mouth, passes the throat, enters the lungs to provide oxygen, and is exhaled through the same pathway.

However, in individuals with sleep apnea syndrome, this normal breathing pattern is repeatedly interrupted during sleep, leading to poor sleep quality, daytime drowsiness, and fatigue the next day. This affects a person's daytime alertness, daily activities, and overall health in multiple ways.

Based on its causes, sleep apnea syndrome is classified into obstructive sleep apnea syndrome, central sleep apnea syndrome, and mixed sleep apnea syndrome. Among these, obstructive sleep apnea syndrome is the most common^[1].

Is sleep apnea syndrome common?

Yes.

The prevalence of this condition is 5% in the general population^[2] and 20%–40% in middle-aged and older adults^[2]. This means that in the general population, about 5 out of 100 people have this condition, while among middle-aged and older adults, 20 to 40 out of 100 people are affected. It is estimated that over 40 million people in China suffer from sleep apnea syndrome^[2].

What are the types of sleep apnea syndrome?

Sleep apnea syndrome is divided into three types: obstructive sleep apnea syndrome, central sleep apnea syndrome, and mixed sleep apnea syndrome:

1. Obstructive sleep apnea syndrome: The main symptoms include alternating episodes of snoring and breathing pauses during sleep. In severe cases, the person may wake up gasping for air, experiencing palpitations, chest tightness, or discomfort in the chest area, followed by daytime sleepiness and fatigue^[1].

2. Central sleep apnea syndrome: The patient may not snore or snore minimally during sleep but may experience difficulty falling asleep, restless sleep, or frequent awakenings. Upon waking, they may have headaches and feel mentally exhausted^[1].

3. Mixed sleep apnea syndrome: Combines symptoms of both types mentioned above.

SYMPTOMS

What are the common manifestations of sleep apnea syndrome?

The main symptoms of sleep apnea syndrome include snoring during sleep accompanied by intermittent pauses in breathing and decreased sleep quality. In severe cases, individuals may wake up gasping for air, experiencing palpitations, chest tightness, or discomfort in the precordial area. They may still feel fatigued after waking and experience excessive daytime sleepiness.

Some patients may not notice any symptoms themselves. For example, if a person sleeps alone for a long time without a bed partner, they may not realize whether they snore or not. Fatigue and daytime sleepiness might also be attributed to overwork or aging, so many people may already have typical symptoms without being aware of them.

Additionally, other common symptoms include increased nighttime urination, morning headaches, dry mouth, daytime difficulty concentrating, memory decline, irritability, mood swings, anxiety, or depression, among others^[1,3].

What serious consequences can sleep apnea syndrome cause?

Sleep apnea syndrome can lead to intermittent hypoxemia and disrupted sleep patterns. This chronic long-term hypoxia can cause damage to multiple organs and systems throughout the body, resulting in conditions such as hypertension, coronary heart disease, arrhythmias, cerebrovascular diseases, cognitive dysfunction, and type 2 diabetes. In severe cases, it may even lead to dangerous situations like heart failure, stroke (commonly known as "brain attack"), or respiratory failure^[1].

CAUSES

What Causes Sleep Apnea Syndrome?

Different types of sleep apnea syndrome have different causes:

1. Obstructive Sleep Apnea Syndrome (OSAS): The primary cause is pathological narrowing of the upper respiratory tract, particularly in the nose and throat, such as obesity, nasal disorders (e.g., deviated septum, nasal polyps, nasopharyngeal tumors), enlarged tonsils, relaxed soft palate, or a large tongue. During sleep, the relaxation of soft tissues and the backward displacement of the tongue cause the soft palate and tongue to collapse against the pharyngeal wall, obstructing the upper airway and leading to obstructive sleep apnea.

2. Central Sleep Apnea Syndrome (CSAS): Often caused by neurological or motor system disorders, such as spinal cord lesions due to vascular embolism, polio, brainstem malformations (e.g., Arnold-Chiari malformation), or familial dysautonomia, which disrupt central respiratory control.

3. Mixed Sleep Apnea Syndrome: Combines both obstructive and central mechanisms^[4].

What Are the Risk Factors for Sleep Apnea Syndrome?

Any factor that narrows the airway or impedes airflow can contribute to poor ventilation, apnea, and hypoxia during sleep, leading to sleep apnea syndrome. Common risk factors include:

1. Age: Prevalence increases with age, peaking around 70 years before stabilizing.

2. Gender: Premenopausal women have a significantly lower risk than men, but postmenopause, the rates equalize.

3. Obesity: Excess fat deposits in the oropharyngeal mucosa (especially at the soft palate level) worsen airway obstruction. A BMI ≥ 28 kg/m² or neck/waist-hip ratios exceeding normal by 20%+ raises risk.

4. Congenital Upper Airway Abnormalities: Short neck, craniofacial or mandibular deformities alter pharyngeal anatomy, narrowing the airway.

5. Alcohol/Sedatives: These relax upper airway muscles, increasing collapsibility and prolonging apneas.

6. Smoking: May elevate risk or exacerbate symptoms.

7. Comorbidities: Stroke, heart failure, hypothyroidism, acromegaly, vocal cord paralysis, neuromuscular diseases, GERD, or mediastinal masses can worsen airway resistance.

Who Is More Likely to Develop Sleep Apnea Syndrome?

1. Most common in obese individuals, especially those with central obesity (thick neck/wide hips).
2. Men are at higher risk than premenopausal women, but postmenopausal rates match.
3. Middle-aged and elderly populations are high-risk groups.
4. Congenital short neck, craniofacial/jaw deformities increase susceptibility.
5. Chronic smokers, alcohol users, or sedative consumers face elevated OSAS risk.
6. Familial clustering occurs due to shared genetics (e.g., anatomical traits) or lifestyle (e.g., obesity)^[1,3].

When Does Sleep Apnea Worsen or Trigger?

Supine sleep position, evening alcohol/sedative use, or hypnotics significantly increase apnea frequency and severity that night.

DIAGNOSIS

What tests are needed for sleep apnea syndrome?

1. Medical history collection: The doctor will first understand the patient's medical history, especially sleep history. They will often ask questions such as "snoring situation," "whether breathing pauses have been observed," "how many times breathing pauses occur in approximately 7 hours of sleep," "sleep quality and frequency of nocturia," "whether there is breath-holding or choking," and "next-day mental state."

2. Physical examination: If sleep apnea syndrome is suspected, the doctor will conduct a comprehensive physical examination to identify potential causes and risk factors. For example, BMI (Body Mass Index, commonly used to assess health based on weight and height; calculated as BMI = weight ÷ height²) will be calculated to determine if the patient is overweight. Neck, hip, and waist circumferences will be measured to calculate the waist-to-hip ratio and assess central obesity. Blood pressure and heart rate will be checked, along with heart and lung examinations. Other checks include evaluating facial morphology for factors like a small jaw, narrow nasal cavity, or narrow pharynx that may affect breathing.

3. Sleep monitoring: Polysomnography (PSG) is the gold standard for diagnosing sleep apnea syndrome and assessing its severity. The process involves attaching monitoring electrodes to the body, similar to an electrocardiogram, but the patient must sleep overnight in a hospital sleep lab with these electrodes. For patients with milder symptoms and no accompanying conditions like hypertension or heart disease, out-of-center sleep testing (OCST) may be an option. This portable device allows the test to be conducted at home.

4. Other auxiliary tests: After diagnosis, further tests such as pulmonary function tests, nasopharyngeal endoscopy, imaging studies (e.g., head CT), and esophageal manometry may be required. However, not all patients need these tests; the doctor will decide based on individual circumstances.

What is the purpose of the above tests for sleep apnea syndrome?

1. Comprehensive physical examination has two main purposes:

   • To identify individuals with risk factors for sleep apnea syndrome, enabling targeted follow-up tests and evaluations.
   • To assess overall physical condition and guide treatment. For example, patients with central obesity may need weight loss as part of their treatment plan, while those with significant nasal or pharyngeal narrowing may require surgery.

2. Polysomnography is the most important test for diagnosing sleep apnea syndrome and evaluating its severity. It also helps identify causes of poor ventilation.

3. Other tests (e.g., pulmonary function tests, nasopharyngeal endoscopy, head CT, esophageal manometry) aim to further clarify the cause of obstructive sleep apnea syndrome. For example, pulmonary function tests assess airway patency and lung capacity, while nasopharyngeal endoscopy checks for nasal structural abnormalities. These tests guide personalized treatment plans and help predict treatment outcomes.

What should sleep apnea syndrome patients pay attention to during polysomnography?

Among the tests for sleep apnea syndrome, polysomnography is the most critical. Due to its特殊性, healthcare staff will explain the following precautions in detail before the test:

1. Arrive at the sleep lab several hours early on the day of the test to familiarize yourself with the environment, ensuring your sleep reflects your usual patterns and isn’t affected by unfamiliar surroundings.
2. Avoid sedatives, alcohol, coffee, cola, tea, etc., on the day of the test, as these may affect the accuracy of the results.
3. Try to minimize daytime napping to ensure better nighttime sleep quality.
4. If you usually wake up at night, reduce water intake before bed to avoid sleep interruptions.
5. Wash your hair and body before the test. Men should shave their facial hair, and avoid using cosmetics to prevent interference with electrode sensitivity.
6. Some facilities provide sleepwear, but most patients wear their own. Choose front-opening pajamas for easy electrode placement.
7. Avoid strenuous exercise and maintain emotional stability before the test to prevent sleep disturbances.
8. Avoid testing during upper respiratory infections, as these may cause airway obstruction and skew results.

Which diseases are easily confused with sleep apnea syndrome?

Sleep apnea syndrome is often confused with other conditions that also involve snoring or poor sleep quality, such as simple snoring, sleep-related hypoventilation, obesity hypoventilation syndrome, narcolepsy, restless legs syndrome and periodic limb movements, panic attacks, and insomnia or drowsiness caused by drugs or other substances^[3].

TREATMENT

How to treat sleep apnea syndrome?

Since sleep apnea syndrome is a systemic condition, comprehensive treatment is required. The primary goals are to improve ventilation, alleviate hypoxia, enhance overall health, and improve quality of life. The main treatment methods include:

1. Etiological treatment:
   If there are underlying conditions causing or exacerbating sleep apnea syndrome, targeted treatment should be administered to address these diseases and eliminate the root cause.

2. General treatment:

   • Overweight (BMI ≥ 24 kg/m²) or obese (BMI ≥ 28 kg/m²) patients should follow medical guidance for appropriate and scientific weight loss;
   • Quit smoking and alcohol, and avoid sedative-hypnotic medications. If such drugs are necessary for specific conditions, discuss the risks and benefits with a doctor regarding sleep apnea syndrome;
   • Adopt proper sleeping positions, such as side sleeping, which can help alleviate snoring symptoms.

3. Non-surgical therapies:
   Non-invasive positive pressure ventilation (NPPV) is the first-line treatment for sleep apnea syndrome. It involves connecting the patient to a ventilator via a nasal mask or full-face mask during sleep to assist mechanical ventilation and relieve apnea. For patients unable to tolerate long-term NPPV, oral appliances may be used under the evaluation and guidance of a dentist.

4. Surgical treatment:
   Surgery is generally not the initial treatment option and is only suitable for patients whose upper airway obstruction can be surgically corrected and who can tolerate the procedure. Examples include cases caused by hypertrophic nasal turbinates, nasal polyps, or enlarged tonsils^[1,3].

What surgical methods are available for treating sleep apnea syndrome?

Common surgical approaches for sleep apnea syndrome include nasal surgery, tonsillectomy and adenoidectomy, uvulopalatopharyngoplasty (UPPP), soft palate implants, tongue base and hyoid surgery, hypoglossal nerve stimulation, distraction osteogenesis, single or double jaw advancement, bariatric surgery, and tracheostomy.

Since the causes of poor ventilation and airway structure vary among patients, a personalized surgical plan should be developed after a comprehensive evaluation by a sleep medicine specialist.

What should be noted after surgery for sleep apnea syndrome?

Regular follow-up visits as prescribed by the doctor are essential.

In addition to post-operative care specific to the surgery, patients may still experience some degree of poor ventilation and hypoxia after the surgical wound heals. Since symptoms like snoring may significantly improve, the remaining ventilation issues and hypoxia can easily be overlooked. Therefore, ongoing follow-up at medical institutions is necessary.

Can sleep apnea syndrome be completely cured?

Sleep apnea syndrome is difficult to cure completely. It is a chronic condition requiring long-term, multidisciplinary management. Even if symptoms improve significantly after treatment, factors triggering sleep apnea may re-emerge with age, changes in physical condition, or the onset of other diseases. Thus, once diagnosed, long-term, regular follow-ups at specialized medical institutions are needed, along with continued avoidance of high-risk factors.

Can sleep apnea syndrome recur?

Recurrence is possible.

The likelihood of recurrence varies depending on the treatment method:

1. If weight loss alone is used for treatment, symptoms are highly likely to return if weight is regained;
2. Non-invasive positive pressure ventilation (NPPV) offers lasting and stable efficacy but is not suitable for all patients;
3. Common surgical methods also carry a certain recurrence rate;
4. An exception is tracheostomy, which has an almost 100% success rate and rarely recurs with proper post-operative care. However, due to its significant trauma and risks like infection or bleeding, it is typically reserved as a last resort for severe cases unresponsive to other treatments.

Additionally, as age and physical condition change, the risk of sleep apnea syndrome increases, making recurrence almost inevitable. Therefore, long-term monitoring and attention are necessary.

Which department should I visit for sleep apnea syndrome?

1. Patients are advised to first visit the respiratory medicine department.

2. If the condition is caused by issues like nasal polyps or enlarged tonsils, an otolaryngology (ENT) department may be appropriate.

3. If symptoms include breath-holding or choking during sleep leading to cyanosis (purple discoloration of the skin or mucous membranes due to hypoxia), emergency care should be sought.

DIET & LIFESTYLE

What should patients with sleep apnea syndrome pay attention to in daily life?

1. In daily life, focus on weight control, avoid being overweight, and refrain from smoking and drinking.
2. Actively treat pre-existing upper respiratory diseases such as nasal or throat conditions, as well as other underlying diseases that may contribute to this disorder.
3. Seek medical attention promptly if symptoms similar to sleep apnea syndrome occur.

What should family members of sleep apnea syndrome patients pay attention to?

The symptoms of sleep apnea syndrome are often first noticed by family members, as many people are unaware of whether they snore. Even if brief pauses in breathing, breath-holding, or waking up gasping occur during sleep, the individual may quickly fall back asleep and not remember the incident. In fact, many people with sleep apnea syndrome are unaware of their abnormal breathing during sleep, and most patients underestimate the severity of their condition.

Therefore, if family members observe obvious snoring, abnormal breathing during sleep, or other characteristic symptoms of sleep apnea syndrome—or signs such as daytime sleepiness, low energy, or mood swings—especially in overweight individuals, they should promptly encourage them to seek medical attention.

PREVENTION

Can Sleep Apnea Syndrome Be Prevented?

While there are currently no effective methods to completely avoid the occurrence of sleep apnea syndrome, reducing risk factors such as avoiding overweight or obesity, smoking, and alcohol consumption can help minimize the risk of developing the condition.