Plain-language definitions grounded in the clinical and regulatory literature.
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Disorder
What it isA condition where the throat repeatedly collapses during sleep, blocking breathing for seconds to a minute at a time, dozens or even hundreds of times per night.
Why it mattersThese breathing interruptions starve your body of oxygen and fragment your sleep. Untreated OSA significantly increases risk of heart disease, stroke, diabetes, and accidents from daytime sleepiness.
Think of it like thisImagine trying to breathe through a straw that keeps getting pinched shut. Your body struggles to get air, briefly wakes up to reopen the straw, then falls back asleep—repeating this cycle all night without you even knowing.
Obstructive sleep apnea (OSA) is a sleep-related breathing disorder characterized by repetitive episodes of complete (apnea) or partial (hypopnea) upper airway obstruction during sleep, resulting in intermittent hypoxemia, hypercapnia, sleep fragmentation, and sympathetic activation.
MechanismOSA results from an imbalance between forces that collapse the upper airway (negative intraluminal pressure during inspiration, gravity) and forces that maintain patency (pharyngeal dilator muscle activity, positive intraluminal pressure from CPAP).
Scientific ConsensusOSA affects approximately 1 billion people globally. It is an independent risk factor for hypertension, atrial fibrillation, heart failure, stroke, and all-cause mortality. CPAP is effective treatment when used consistently.
Active DebateWhy CPAP has not consistently reduced cardiovascular events in clinical trials despite improving intermediate endpoints, and whether this reflects adherence limitations or fundamental questions about the OSA-cardiovascular relationship.
Emerging ResearchOSA phenotyping based on anatomical, neuromuscular, arousal threshold, and loop gain traits; Pharmacological targeting of specific phenotypic traits; The relationship between OSA and dementia/cognitive decline
Key ResearchSeminal epidemiology from the Wisconsin Sleep Cohort (Young et al., 1993) established OSA prevalence. The Sleep Heart Health Study linked OSA to cardiovascular outcomes. Recent phenotyping frameworks (Eckert et al., 2013) are reshaping treatment approaches.
— Wisconsin Sleep Cohort establishing OSA prevalence in a working-age population, finding 4% of men and 2% of women met diagnostic criteria — the foundational epidemiological reference.
— Comprehensive review of OSA pathophysiology covering upper airway anatomy, pharyngeal collapsibility, ventilatory control instability, and arousal threshold as the four mechanistic pillars.
— Updated Wisconsin cohort data showing OSA prevalence has increased substantially since the 1990s, with 17% of men and 9% of women meeting AHI threshold criteria.
— Prospective study showing untreated severe OSA (AHI >30) significantly increases fatal and non-fatal cardiovascular events, which CPAP treatment substantially reduces.
— Reviews the cardiovascular consequences of OSA including hypertension, arrhythmia, coronary artery disease, and stroke, with mechanistic pathways through sympathetic activation, inflammation, and oxidative stress.
— Reviews epidemiology and diagnosis of OSA, covering AHI thresholds, polysomnography versus home sleep testing, and limitations of AHI as the sole severity metric.
Javaheri S, Barbe F, Campos-Rodriguez F (2017)
— Comprehensive review of OSA and cardiovascular disease mechanisms, covering atrial fibrillation, heart failure, and the evidence base for CPAP in reducing cardiac risk.
— Identifies four physiological phenotypes of OSA (collapsibility, arousal threshold, loop gain, muscle responsiveness), enabling precision phenotyping for non-CPAP therapies.
— Establishes hypoxic burden as superior to AHI for cardiovascular mortality prediction, shifting the conceptual framework for OSA severity assessment.
— AHA/ACC scientific statement on sleep apnea and cardiovascular disease, integrating epidemiological and mechanistic evidence for clinical practice recommendations.
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