Classification and Symptoms
- Obstructive sleep apnea is classified as a sleep-related breathing disorder.
- It is divided into two categories: adult OSA and paediatric OSA.
- Obstructive sleep apnea is different from central sleep apnea.
- The respiratory effort is assessed to classify the apnea as obstructive.
- Obstructive sleep apnea-hypopnea syndrome is associated with daytime symptoms.
- Common symptoms of OSA syndrome include daytime sleepiness, restless sleep, and loud snoring.
- Less common symptoms include morning headaches, insomnia, and mood changes.
- OSA can be transient and caused by upper respiratory infections or drug use.
- Epstein-Barr virus can increase the size of lymphoid tissue and cause OSA.
- OSA can be underdiagnosed in individuals who sleep alone.
- Excessive daytime sleepiness is a hallmark symptom of OSA in adults.
- OSA can cause changes in the neurons of the hippocampus and frontal cortex.
- OSA is associated with problems in non-verbal information processing and memory.
- Diagnosis of OSA is more common among people in relationships.
- There is a stigma associated with loud snoring, particularly in females.
- Hypersomnolence is not typical in young children with sleep apnea.
- Children with severe OSA may appear over-tired or hyperactive.
- OSA in children is often caused by obstructive tonsils and adenoids.
- Excessive weight can also contribute to OSA in children.
- The prevalence and characteristics of paediatric OSA have changed due to obesity.

Risk Factors
- Obesity is a significant risk factor for OSA.
- Fatty infiltration and fat deposits in the neck region can narrow the upper airway.
- The severity of OSA is proportional to the degree of obesity.
- Adenotonsillar hypertrophy is a common cause of OSA in children.
- Changes in the prevalence and characteristics of paediatric OSA are linked to the obesity epidemic.
- People with normal body mass indices (BMIs) can also have OSA, possibly due to increased muscle mass or decreased muscle tone.
- Sleeping supine (on the back) and gravity can contribute to OSA development, confounded by neck obesity.
- Use of CPAP can expand a collapsed upper airway, indicating airway collapse as the cause of OSA.
- Throat lesions, especially enlarged tonsils, can aggravate OSA and their removal may provide relief.
- Old age is often accompanied by muscular and neurological loss of upper airway muscle tone.
- Decreased muscle tone can be caused by chemical depressants like alcohol and sedatives.
- Permanent premature muscular tonal loss can be caused by traumatic brain injury, neuromuscular disorders, or poor adherence to treatments.
- Age-related changes in muscle tone can increase the risk of OSA.
- Post-menopausal women have a prevalence of OSA similar to men in the same age range.
- Decreased muscle tone and increased soft tissue around the airway increase the risk of OSA.
- Men, with increased mass in the torso and neck, are at higher risk of developing sleep apnea.
- Women generally experience OSA less frequently and to a lesser degree due to physiology and possibly progesterone levels.
- Post-menopausal women have a higher risk of developing OSA.
- Medications and lifestyle factors can also contribute to OSA risk.
- OSA has a genetic component.
- Family history increases the likelihood of developing OSA.
- Genetic factors play a role in OSA development.
- Short lower jaws (neoteny) can cause OSA.
- Narrow upper jaw contributes to OSA.
- Small lower jaws can lead to crowded teeth and malocclusions.
- Craniofacial syndromes can involve unusual facial features.
- Down syndrome predisposes individuals to OSA.
- OSA can occur as a post-operative complication.
- Pharyngeal flap surgery is associated with post-operative OSA.
- Flap obstruction can hinder respiration during sleep.
- Healthcare professionals are becoming more aware of post-operative OSA.
- Concerns of OSA have increased following pharyngeal flap surgery.

Pathophysiology
- Transition from wakefulness to sleep is associated with reduced upper-airway muscle tone.
- During REM sleep, muscle tone of the throat and neck relax, potentially obstructing airflow.
- Neurological mechanisms can trigger sudden interruptions of sleep, causing gasping for air and awakening.
- Sleep interruptions can lead to sleep deprivation and negative effects on growth, healing, and immune response.
- Blocked upper airway, usually behind the tongue and epiglottis, is the fundamental cause of OSA.
- Spontaneous upper-airway blockage causes are debated.
- Pulmonologists and neurologists believe risk factors can be advanced age, brain injury, decreased muscle tone, long-term snoring, and increased soft tissue.
- Otorhinolaryngologists believe risk factors can be structural features like enlarged tonsils, enlarged posterior tongue, fat deposits, impaired nasal breathing, floppy soft palate, or collapsible epiglottis.
- Oral and maxillofacial surgeons believe risk factors can be primary forms of mandibular hypoplasia leading to glossoptosis.
- Orthognathic surgery is believed to offer superior guarantees of OSA cure by some maxillofacial surgeons.

Consequences
- OSA has physiological consequences such as hypoxia and sleep fragmentation.
- Intermediate consequences include inflammation and metabolic dysfunction.
- Clinical repercussions include pulmonary hypertension and heart diseases.
- OSA can lead to accidents and obesity.
- Increased risk of perioperative complications in patients with OSA.
- OSA is the most common Sleep-Disordered Breathing in children.
- Pre-term children are more likely to have OSA.
- Untreated OSA in children can lead to long-term consequences.
- OSA affects various domains of life, including organs and behavior.
- Nocturnal symptoms of OSA are associated with daytime symptoms and neuroc