| Most Common Type | Obstructive Sleep Apnea (OSA) (National Heart, Lung, and Blood Institute (NHLBI)) |
| Estimated US Adults Affected | ~25 million (American Academy of Sleep Medicine) |
| Diagnostic Standard | Polysomnography (in-lab) or Home Sleep Apnea Test |
| Severity Measured By | Apnea-Hypopnea Index (AHI) |
| Higher Risk Groups | Men, older adults, individuals with obesity (CDC, NHLBI) |
What Is Sleep Apnea?
Sleep apnea is a condition in which breathing repeatedly stops and starts during sleep. These interruptions — called apneic events — can occur dozens or even hundreds of times per night, often without the person waking fully or remembering them in the morning.
There are three main types:
- Obstructive sleep apnea (OSA): The most common form, caused by the throat muscles relaxing and partially or fully blocking the airway.
- Central sleep apnea (CSA): Occurs when the brain fails to send proper signals to the muscles that control breathing.
- Complex (mixed) sleep apnea: A combination of both obstructive and central types.
OSA accounts for the large majority of diagnosed cases in the US. Despite its prevalence, the condition remains significantly underdiagnosed, partly because its most obvious symptoms happen while the individual is asleep.
Apnea
A temporary cessation of breathing. In sleep apnea, these pauses occur repeatedly during sleep and typically last at least 10 seconds.
Apnea-Hypopnea Index (AHI)
A measure of sleep apnea severity calculated as the average number of apnea and hypopnea events per hour of sleep. Higher numbers indicate more severe disruption.
Hypopnea
A partial reduction in airflow during sleep — less complete than a full apnea, but still significant enough to lower blood oxygen levels or disrupt sleep.
Polysomnography
A comprehensive, multi-channel sleep study conducted in a clinical setting that records brain waves, oxygen levels, heart rate, and other physiological data during sleep.
Oxygen Saturation
The percentage of hemoglobin in the blood that is carrying oxygen. Repeated breathing pauses in sleep apnea can cause oxygen saturation to drop, which places stress on the cardiovascular system.
Recognizing the Symptoms
Because sleep apnea disrupts rest without always causing full waking, many people live with symptoms for years before seeking evaluation. Common signs include:
- Loud, persistent snoring — particularly snoring punctuated by gasping or choking sounds
- Excessive daytime sleepiness, even after a full night in bed
- Morning headaches or dry mouth upon waking
- Difficulty concentrating, memory lapses, or mood changes
- Observed breathing pauses reported by a bed partner
- Frequent nighttime urination (nocturia)
Not everyone with sleep apnea snores, and not everyone who snores has sleep apnea. A healthcare provider is the appropriate person to distinguish between them based on clinical assessment.
| Most Common Type | Obstructive Sleep Apnea (OSA) (National Heart, Lung, and Blood Institute (NHLBI)) |
| Estimated US Adults Affected | ~25 million (American Academy of Sleep Medicine) |
| Diagnostic Standard | Polysomnography (in-lab) or Home Sleep Apnea Test |
| Severity Measured By | Apnea-Hypopnea Index (AHI) |
| Higher Risk Groups | Men, older adults, individuals with obesity (CDC, NHLBI) |
Who Is Most at Risk?
Several factors are associated with a higher likelihood of developing sleep apnea. Understanding these can help people recognize when it is worth discussing the topic with a doctor.
~80%
Estimated portion of moderate-to-severe OSA cases undiagnosed
Commonly cited in sleep medicine literature; many adults with clinically significant OSA remain unidentified.
2–3×
Increased hypertension risk with untreated OSA
Research published in sleep medicine journals links untreated obstructive sleep apnea to elevated cardiovascular risk.
- Excess weight: Fat deposits around the upper airway can narrow the passage, increasing obstruction risk.
- Neck circumference: A thicker neck may indicate narrower airways. Measurements above approximately 17 inches in men and 15 inches in women are sometimes used as one screening indicator.
- Sex and age: OSA is more common in men, though the gap narrows after menopause in women. Risk generally increases with age.
- Family history: Genetic factors influencing airway anatomy and muscle tone play a role.
- Nasal congestion: Chronic nasal blockage — from allergies or structural issues — increases obstructive risk.
- Alcohol and sedative use: These relax throat muscles and can worsen airway collapse during sleep.
- Smoking: Associated with inflammation and fluid retention in the upper airway.
Certain medical conditions, including type 2 diabetes, high blood pressure, and heart disease, are also associated with higher rates of sleep apnea. The relationship is bidirectional — untreated sleep apnea may worsen these conditions over time.
How Diagnosis Typically Works
If sleep apnea is suspected, a healthcare provider will usually begin with a detailed clinical history and possibly a physical examination of the airway, neck, and mouth. Several tools are used to screen and confirm a diagnosis:
- Questionnaires: Standardized tools such as the Epworth Sleepiness Scale or STOP-BANG questionnaire help gauge symptom severity and risk level.
- Home sleep apnea test (HSAT): A portable monitoring device worn overnight at home that records breathing patterns, oxygen levels, and heart rate. Appropriate for straightforward OSA cases.
- In-lab polysomnography (PSG): A comprehensive overnight sleep study conducted in a clinical sleep center. Technicians monitor brain activity, eye movement, muscle activity, oxygen saturation, and more. Recommended when central sleep apnea, other sleep disorders, or complex medical histories are involved.
Results are reported as the Apnea-Hypopnea Index (AHI) — the average number of breathing events per hour of sleep. Mild OSA is generally classified as 5–14 events per hour; moderate as 15–29; and severe as 30 or more. These thresholds guide treatment decisions made by a clinician.
If you or someone you know experiences consistent symptoms, speaking with a primary care physician is the appropriate first step. Early evaluation and, if needed, treatment can meaningfully reduce the health risks associated with untreated sleep apnea.
This article provides general health information and education only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider regarding any symptoms or health concerns.