Sleep Apnea

Overview

Sleep apnea is a chronic sleep-related breathing disorder characterized by repeated episodes of partial or complete cessation of airflow during sleep, resulting in intermittent hypoxia and sleep fragmentation [1,2]. These breathing disturbances disrupt normal sleep architecture and place sustained physiological stress on the cardiovascular, metabolic, and nervous systems.

The most prevalent form is obstructive sleep apnea (OSA), caused by recurrent collapse of the upper airway during sleep. Central sleep apnea (CSA), which results from impaired respiratory drive, and mixed sleep apnea are less common but clinically significant subtypes [1,3].

Sleep apnea is widely underdiagnosed despite its high prevalence. Global estimates suggest that nearly one billion adults worldwide may have some degree of OSA, with hundreds of millions experiencing moderate-to-severe disease requiring clinical management [4].

&nbsp;

Causes

Sleep apnea develops due to a complex interaction of anatomical, neuromuscular, metabolic, and environmental factors. It is not solely a consequence of poor sleep habits.

Key contributors include:

<ul>
	<li>Reduced upper-airway muscle tone during sleep [2]</li>
	<li>Anatomically narrow upper airway or craniofacial abnormalities [1]</li>
	<li>Excess adipose tissue around the neck and upper airway [2,5]</li>
	<li>Impaired central respiratory control (in CSA) [3]</li>
	<li>Alcohol and sedative use, which increase airway collapsibility [6]</li>
</ul>

&nbsp;

Types

1. Obstructive Sleep Apnea (OSA) 

The most common form, caused by repeated upper-airway obstruction despite ongoing respiratory effort [1].

2. Central Sleep Apnea (CSA)

Characterized by absent or reduced respiratory effort due to impaired brainstem signaling [3].

3. Mixed or Complex Sleep Apnea

A combination of obstructive and central features, sometimes observed during treatment initiation [1].

&nbsp;

Signs & Symptoms

<ul>
	<li>Night-time Symptoms</li>
	<li>Loud, habitual snoring</li>
	<li>Witnessed breathing pauses</li>
	<li>Gasping or choking during sleep</li>
	<li>Frequent awakenings and restless sleep</li>
	<li>Nocturia [6]</li>
</ul>

Day-time Symptoms

<ul>
	<li>Excessive daytime sleepiness</li>
	<li>Morning headaches</li>
	<li>Fatigue and non-restorative sleep</li>
	<li>Impaired concentration and memory</li>
	<li>Mood changes and irritability [6]</li>
	<li>Children may present with behavioral problems, hyperactivity, or learning difficulties rather than sleepiness [2].</li>
</ul>

Untreated sleep apnea is associated with significant short- and long-term health consequences, including:

<ul>
	<li>Hypertension and resistant hypertension [7]</li>
	<li>Atrial fibrillation and cardiac arrhythmias [7]</li>
	<li>Coronary artery disease, heart failure, and stroke [7]</li>
	<li>Type 2 diabetes and insulin resistance [8]</li>
	<li>Increased risk of motor vehicle and occupational accidents</li>
	<li>Depression, anxiety, and reduced quality of life [6]</li>
	<li>Intermittent hypoxia and repeated sympathetic nervous system activation are key mechanisms linking sleep apnea to cardiometabolic disease [7].</li>
</ul>

&nbsp;

Diagnosis

Diagnosis requires both clinical evaluation and objective sleep testing.

Clinical Assessment

Initial evaluation includes assessment of symptoms, risk factors, physical examination, and comorbid conditions.

Sleep Testing

According to the American Academy of Sleep Medicine, diagnostic testing should be performed using either [9]:

1. In-laboratory polysomnography (PSG), or

2. Home sleep apnea testing (HSAT) in carefully selected adults with high suspicion of uncomplicated OSA

Severity Classification

Severity is commonly assessed using the Apnea&ndash;Hypopnea Index (AHI):

<ul>
	<li>Normal: &lt;5 events/hour</li>
	<li>Mild: 5&ndash;14 events/hour</li>
	<li>Moderate: 15&ndash;29 events/hour</li>
	<li>Severe: &ge;30 events/hour [10]</li>
</ul>

Clinical decision-making should also consider symptom burden and comorbid risk, not AHI alone.

&nbsp;

Management

Management strategies are individualized based on disease severity, symptoms, patient anatomy, and associated conditions.

Positive Airway Pressure (PAP) Therapy

PAP therapy is the cornerstone of treatment for moderate-to-severe OSA and symptomatic disease. It improves daytime sleepiness, quality of life, and blood pressure control when used consistently [11].

Weight Management

Weight reduction can significantly reduce OSA severity in individuals with overweight or obesity and is recommended as part of a comprehensive management plan [5].

Oral Appliance Therapy

Mandibular advancement devices may be considered for mild-to-moderate OSA or in patients intolerant of PAP therapy [11].

Surgical Interventions

Surgical options may be considered in selected patients with correctable anatomical obstruction or PAP intolerance, though outcomes vary [1].

&nbsp;

Key Points

<ul>
	<li>Sleep apnea is a common, chronic, and underdiagnosed condition with significant cardiometabolic consequences [4,7].</li>
	<li>Obstructive sleep apnea accounts for the majority of cases and is strongly associated with obesity and aging [2,5].</li>
	<li>Diagnosis requires objective sleep testing interpreted alongside clinical features [9].</li>
	<li>Positive airway pressure therapy remains the most effective treatment for moderate-to-severe disease [11].</li>
	<li>Long-term management and adherence are critical to reducing health risks and improving outcomes.</li>
</ul>

<h3>References&nbsp;</h3>

<ol>
	<li style="list-style-type:decimal">National Heart, Lung, and Blood Institute. (2025). What is sleep apnea?<a href="https://www.nhlbi.nih.gov/health/sleep-apnea" style="text-decoration:none"> https://www.nhlbi.nih.gov/health/sleep-apnea</a></li>
	<li style="list-style-type:decimal">National Heart, Lung, and Blood Institute. (2025). Sleep apnea causes and risk factors.<a href="https://www.nhlbi.nih.gov/health/sleep-apnea" style="text-decoration:none"> https://www.nhlbi.nih.gov/health/sleep-apnea</a></li>
	<li style="list-style-type:decimal">Cleveland Clinic. (2025). Sleep apnea: Causes, symptoms, and treatment.<a href="https://my.clevelandclinic.org/health/diseases/8718-sleep-apnea" style="text-decoration:none"> https://my.clevelandclinic.org/health/diseases/8718-sleep-apnea</a></li>
	<li style="list-style-type:decimal">Benjafield, A. V., et al. (2019). Estimation of the global prevalence and burden of obstructive sleep apnoea. The Lancet Respiratory Medicine, 7(8), 687&ndash;698.<a href="https://doi.org/10.1016/S2213-2600(19)30198-5" style="text-decoration:none"> https://doi.org/10.1016/S2213-2600(19)30198-5</a></li>
	<li style="list-style-type:decimal">Peppard, P. E., et al. (2013). Longitudinal study of moderate weight change and sleep-disordered breathing. JAMA, 284(23), 3015&ndash;3021.</li>
	<li style="list-style-type:decimal">Mayo Clinic. (2025). Obstructive sleep apnea &ndash; Symptoms and causes.<a href="https://www.mayoclinic.org/diseases-conditions/obstructive-sleep-apnea" style="text-decoration:none"> https://www.mayoclinic.org/diseases-conditions/obstructive-sleep-apnea</a></li>
	<li style="list-style-type:decimal">Yeghiazarians, Y., et al. (2021). Obstructive sleep apnea and cardiovascular disease. Circulation, 144(3), e56&ndash;e67.<a href="https://doi.org/10.1161/CIR.0000000000000988" style="text-decoration:none"> https://doi.org/10.1161/CIR.0000000000000988</a></li>
	<li style="list-style-type:decimal">Reutrakul, S., &amp; Mokhlesi, B. (2017). Obstructive sleep apnea and diabetes. Chest, 152(5), 1070&ndash;1086.</li>
	<li style="list-style-type:decimal">Kapur, V. K., et al. (2017). Clinical practice guideline for diagnostic testing for adult obstructive sleep apnea. Journal of Clinical Sleep Medicine, 13(3), 479&ndash;504.</li>
	<li style="list-style-type:decimal">Cleveland Clinic. (2025). Apnea&ndash;hypopnea index (AHI).<a href="https://my.clevelandclinic.org/health/articles/apnea-hypopnea-index-ahi" style="text-decoration:none"> https://my.clevelandclinic.org/health/articles/apnea-hypopnea-index-ahi</a></li>
	<li style="list-style-type:decimal">Patil, S. P., et al. (2019). Treatment of adult obstructive sleep apnea with positive airway pressure. Journal of Clinical Sleep Medicine, 15(2), 335&ndash;343.<a href="https://doi.org/10.5664/jcsm.7640" style="text-decoration:none"> https://doi.org/10.5664/jcsm.7640</a></li>
</ol>

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