Nighttime apneas represent a sleep disorder that results in the cessation of breathing for a period of at least 10 seconds, enough time to reduce the levels of oxygen in the blood and brain while simultaneously increasing carbon dioxide levels. It is estimated that this disorder affects approximately 5% of the adult population. Its severity is proportional to the frequency and duration of apnea episodes and the complications it can lead to: cardiovascular disorders, hypertension, stroke, atrial fibrillation, and heart failure.

The three types of nighttime apnea

There are three different types of nighttime apnea: obstructive sleep apnea, central sleep apnea, and mixed apnea.

Obstructive Sleep Apnea (OSA)

This is the most common variety of this disorder and is caused by a “mechanical” obstruction of the throat or upper airways that occurs during sleep, resulting in repeated breathing interruptions (from 5 to 30 per hour). Various factors may contribute to airway narrowing, with the main ones being obesity (especially with fat distribution around the neck) and natural tissue aging. Smoking, alcohol abuse, and prolonged use of sedatives also contribute, as do low levels of thyroid hormones (hypothyroidism) and abnormal growth due to excessive growth hormone production.

A specific category of sleep apnea affects children and may be caused by enlarged tonsils or adenoids, certain dental issues like deep bite, or congenital defects such as a particularly small jaw. Since snoring is quite common among children, symptoms indicating nighttime apnea include various manifestations mainly observable during the day: mouth breathing, morning headaches, difficulty concentrating, and learning and behavioral disorders.

Central Sleep Apnea

This type of nighttime apnea is linked to a neurological disorder and is much rarer than other forms. It is caused by dysfunction of the brainstem, the region of the brain responsible for regulating breathing based on the amount of carbon dioxide in the blood. Normally, the brainstem instructs the respiratory muscles to contract more strongly and take deep breaths when it detects high carbon dioxide levels, thus expelling excess gas through exhalation.

Conversely, central sleep apnea occurs when the brainstem is less sensitive to changes in CO2 levels, resulting in shallower and slower breathing.

Causes of this type of apnea include prolonged use of certain medications and prolonged stays at high altitudes; central sleep apnea may also occur in individuals with heart failure.

Mixed Sleep Apnea

As the name suggests, mixed sleep apnea is linked to a combination of neurological and obstructive causes. Given its characteristics, it should be considered and treated as obstructive apnea.

Nighttime Apnea: Symptoms

All types of sleep apnea are characterized by symptoms that may be noticed primarily by the bed partner. In affected individuals, breathing slows down significantly or stops completely for prolonged periods, eventually returning to normal rhythm.

Since the disorder significantly worsens sleep quality (the individual never reaches a satisfying and restful level of sleep), those with nighttime apneas are particularly sleepy, fatigued, and irritable during the day, and may experience morning headaches and difficulty concentrating. Additionally, reduced oxygen levels in the blood can cause episodes of atrial fibrillation and increased blood pressure.

Finally, abrupt nighttime awakenings (called “arousals”) that many OSAS patients experience are associated with episodes of stress, excessive release of catecholamines and cortisol, and repeated hormone peaks throughout the night, which may exacerbate cardiovascular or metabolic conditions such as ischemic heart disease, hypertension, or diabetes; high red blood cell counts can also be a sign of OSAS, which can also affect pulmonary artery vasoconstriction, leading to pulmonary hypertension.

Excessive daytime sleepiness can also cause excessive tiredness, easy fatigability, and “microsleeps” during work or driving, posing risks of accidents, especially for individuals in high-risk occupations (truck or bus drivers, long-distance commuters, scaffolders, or industrial machine operators).

The main symptom remains snoring, particularly loud snoring with periods of gasping for breath, breathing pauses, and sudden awakenings (“arousals”) followed by the feeling of choking.

Diagnosing Nighttime Apnea

The specialist responsible for diagnosing nighttime apneas is the pulmonologist, and the main diagnostic tool is polysomnography, an objective instrumental examination that provides precise indications of sleep disorders otherwise difficult to identify. The examination is usually conducted at the patient’s home, applying a series of electrodes and sensors to record all parameters necessary for evaluating apnea episodes: chest movement, airflow at the mouth, and peripheral blood oxygen saturation.

In some cases, particularly severe symptoms may require polysomnography to be performed in a hospital setting using more specific equipment capable of also recording nocturnal electroencephalograms.

Treating Nighttime Apneas

Nighttime apnea can be treated with medical or surgical therapies. Medical therapy for OSAS typically involves the use of CPAP (Continuous Positive Air Pressure), a mask that delivers air during sleep. The continuous positive air pressure in the upper airways prevents breathing relaxation and the onset of snoring and apneas. The effectiveness of this treatment is usually evaluated through CPAP-applied polysomnography to assess the disappearance of apnea events.

When patients have airway abnormalities or pathologies causing airway obstruction, surgical intervention may be necessary. The goal of surgery is to address points of greatest constriction, making airflow less difficult. Areas targeted may include the nose, soft palate, base of the tongue, jaw, tonsils, and adenoids. The specialist performing surgeries for nighttime apneas is the otolaryngologist. Surgery can help resolve issues related to nighttime apneas; however, especially in severe cases, it is always necessary to combine surgery with medical therapies and possibly modify habits and lifestyle.

The Role of Prevention in Combating Sleep Apnea

Issues related to nighttime breathing can be significantly alleviated by adopting healthy habits such as a balanced diet, quitting smoking, avoiding excessive alcohol consumption, and refraining from taking sedative medications, especially in the evening. In obese patients, drastic weight loss (through dietary interventions or, in severe cases, bariatric surgery) can drastically reduce apnea episodes.