From the Guidelines
Sleep apnea is primarily caused by a combination of factors, including physical obstructions in the airway, disruptions in brain signals that control breathing during sleep, genetics, anatomical characteristics, functional traits, age, sex, body mass index (BMI), and lifestyle. The most common form, obstructive sleep apnea, occurs when throat muscles relax excessively, allowing soft tissues to collapse and block the airway 1. Risk factors include obesity (excess fat deposits around the upper airway), large neck circumference, enlarged tonsils or adenoids, nasal congestion, and certain anatomical features like a small jaw or recessed chin.
Some of the key factors that contribute to sleep apnea include:
- Genetics: sleep apnea can run in families, suggesting a genetic component 1
- Anatomical characteristics: narrow upper airway, abnormalities in craniofacial structure 1
- Functional traits: airway collapsibility, upper airway muscle responsiveness, arousability and breathing instability 1
- Age and sex: sleep apnea becomes more common in older adults as muscle tone decreases, and is more common in men than women 1
- Body mass index (BMI): excess weight can increase the risk of sleep apnea 1
- Lifestyle factors: alcohol consumption, smoking, and use of sedatives can worsen sleep apnea by relaxing throat muscles 1
The most recent and highest quality study suggests that sleep apnea is a complex condition, resulting from the interplay of multiple factors, and that a comprehensive approach is needed to diagnose and treat the condition 1. Central sleep apnea, less common, results from the brain failing to transmit proper signals to breathing muscles and is often associated with heart disorders, stroke, or narcotic medications. Genetics may play a role in both types, explaining why sleep apnea sometimes runs in families.
It is essential to note that sleep apnea can have significant consequences on morbidity, mortality, and quality of life, including increased risk of cardiovascular disease, high blood pressure, and decreased cognitive function 1. Therefore, early diagnosis and treatment are crucial to prevent these complications.
From the Research
Causes of Sleep Apnea
The causes of sleep apnea are complex and multifaceted. Some of the key factors that contribute to the development of sleep apnea include:
- Obesity, which is a major risk factor for sleep apnea 2, 3, 4
- Anatomical abnormalities, such as a narrow airway or enlarged tonsils, which can obstruct the flow of air during sleep 5
- Neuromuscular disorders, such as hypoglossal nerve dysfunction, which can affect the ability of the upper airway muscles to keep the airway open during sleep 5
- Hormonal imbalances, such as those that occur during pregnancy or menopause, which can increase the risk of sleep apnea 3
- Certain medications, such as sedatives and tranquilizers, which can relax the muscles in the throat and increase the risk of airway obstruction 3
Risk Factors for Sleep Apnea
In addition to the causes of sleep apnea, there are several risk factors that can increase an individual's likelihood of developing the condition. These include:
- Age, with sleep apnea becoming more common after the age of 40 2, 3
- Gender, with men being more likely to develop sleep apnea than women 2, 3
- Family history, with individuals who have a family history of sleep apnea being more likely to develop the condition 3
- Smoking, which can increase the risk of sleep apnea by causing inflammation and narrowing of the airway 3
- Nasal congestion, which can increase the risk of sleep apnea by causing mouth breathing and increasing the likelihood of airway obstruction 3
Pathophysiology of Sleep Apnea
The pathophysiology of sleep apnea involves the intermittent collapse of the upper airway during sleep, which can lead to reductions in oxygen levels and disruptions in sleep quality 5. This can be caused by a variety of factors, including:
- Loss of tonic input to the upper airway dilator muscle motor neurons, which can lead to collapse of the pharyngeal airway 5
- Increased sensitivity of the chemoreceptors, which can lead to excessive daytime sympathetic vasoconstrictor activity and increased blood pressure 5
- Overproduction of superoxide ion and inflammatory effects on resistance vessels, which can contribute to the development of hypertension and other cardiovascular diseases 5