How Sleep Apnea Is Diagnosed and Treated

Stopping Breathing 400 Times a Night—and Not Knowing It

An estimated 39 million Americans have obstructive sleep apnea, according to the American Academy of Sleep Medicine. Most are undiagnosed. The condition causes the airway to partially or completely collapse during sleep, cutting off breathing for ten seconds to more than a minute at a time. A person with severe sleep apnea may stop breathing more than 30 times per hour—over 240 times during an eight-hour night. Each episode rouses the brain just enough to restore muscle tone and reopen the airway, never fully waking the person but fragmenting sleep into hundreds of micro-arousals. The result is exhaustion that feels inexplicable. The consequences extend well beyond fatigue.

The Apnea-Hypopnea Index: Measuring Severity

Sleep apnea severity is quantified using the Apnea-Hypopnea Index (AHI), which counts the number of breathing disruptions per hour of sleep. An apnea is a complete cessation of airflow for at least ten seconds; a hypopnea is a partial reduction in airflow of at least 30% with an associated drop in blood oxygen or arousal from sleep.

AHI alone doesn't capture the full clinical picture. Oxygen desaturation—how low blood oxygen falls during events—matters independently. A patient with an AHI of 20 whose oxygen drops to 75% has more severe physiological stress than one whose oxygen stays above 90%. The T90 index (percentage of sleep time below 90% oxygen saturation) supplements AHI in clinical assessment.

Diagnosing Sleep Apnea: Two Pathways

Two diagnostic approaches are currently in clinical use: in-laboratory polysomnography (PSG) and home sleep apnea testing (HSAT).

Polysomnography is the gold standard. Conducted in a sleep lab overnight, it measures:

• Electroencephalography (EEG) — brain wave activity and sleep stage identification
• Electromyography (EMG) — chin and leg muscle activity (detects limb movement disorders)
• Electrooculography (EOG) — eye movements distinguishing REM from non-REM sleep
• Airflow via nasal/oral thermistor and pressure transducer
• Respiratory effort via chest and abdominal belts
• Pulse oximetry — continuous blood oxygen saturation
• EKG — cardiac rhythm monitoring

Home sleep apnea testing uses a portable device that records airflow, oxygen saturation, respiratory effort, and pulse rate. HSATs are less sensitive than PSG—they miss central sleep apnea, underestimate AHI, and cannot diagnose other sleep disorders—but they are less expensive (roughly $150–$300 versus $1,000–$3,500 for PSG) and more accessible. The American Academy of Sleep Medicine endorses HSATs for uncomplicated cases with high pre-test probability of moderate-to-severe obstructive sleep apnea.

CPAP: The Primary Treatment

Continuous Positive Airway Pressure (CPAP) therapy is the most effective treatment for moderate-to-severe obstructive sleep apnea. A CPAP machine generates a continuous stream of pressurized air—typically 5 to 20 centimeters of water pressure—delivered through a mask that covers the nose, the nose and mouth, or the entire face. This pneumatic splint keeps the upper airway open throughout the breathing cycle, preventing the soft tissue collapse that causes apnea events.

CPAP immediately eliminates virtually all apnea events in compliant users. AHI drops to under 5. Blood oxygen saturation normalizes. Daytime sleepiness resolves within days to weeks. The cardiovascular benefits accumulate over months and years.

Cardiovascular consequences of untreated sleep apnea are substantial and well-documented:

• 2–3x increased risk of myocardial infarction (heart attack)
• Hypertension that is often resistant to multiple medications until sleep apnea is treated
• 2–4x increased risk of atrial fibrillation
• Increased risk of stroke, particularly in men
• Type 2 diabetes association (sleep fragmentation disrupts glucose metabolism)

The major limitation of CPAP is adherence. Studies consistently show that 30–50% of CPAP users either abandon the device within the first year or use it fewer than four hours per night—the CMS-defined minimum for "compliant" usage. The pressure, mask interface, and noise create barriers that are genuinely difficult for some patients.

Alternatives When CPAP Fails

Several evidence-based alternatives exist for patients who cannot tolerate CPAP.

Mandibular Advancement Devices (MADs) are oral appliances fitted by dentists trained in dental sleep medicine. They reposition the lower jaw forward during sleep, enlarging the retroglossal and retropalatal airspace. MADs are less effective than CPAP—they reduce AHI by 50–60% rather than 80–90%—but adherence is substantially higher. For patients with mild-to-moderate sleep apnea who reject CPAP, MADs represent a clinically meaningful alternative.

Positional therapy is relevant for patients whose sleep apnea is predominantly position-dependent—worse when sleeping supine. Vibrating wearable devices that prompt position changes when the patient rolls onto their back can reduce AHI significantly in this subset.

Hypoglossal Nerve Stimulation: The Implanted Option

Inspire Medical Systems' Upper Airway Stimulation (UAS) therapy received FDA approval in 2014. A surgically implanted device stimulates the hypoglossal nerve—which controls tongue muscle tone—synchronized with each breath. This prevents the tongue from falling back and obstructing the airway. A 2014 study in the New England Journal of Medicine showed 68% median AHI reduction with Inspire, with 78% of patients below an AHI of 20. Eligibility requires moderate-to-severe OSA, CPAP failure, BMI under 35, and specific anatomy (absence of concentric palatal collapse, assessed during a drug-induced sleep endoscopy).

Surgical Options and Weight Loss

Uvulopalatopharyngoplasty (UPPP) removes excess soft tissue from the throat including the uvula and portions of the soft palate. Results are variable: approximately 50% of patients achieve meaningful AHI reduction, and success is difficult to predict preoperatively. UPPP does not work in patients whose obstruction occurs at the tongue base rather than the palate.

Weight loss is mechanically intuitive—adipose tissue deposited around the pharynx compresses the airway. A 10% reduction in body weight produces approximately a 26% reduction in AHI on average. Bariatric surgery can achieve more dramatic results: a 2021 Swedish Obese Subjects study found resolution or major improvement of sleep apnea in 72% of patients five years after bariatric surgery.

This article is for informational purposes only. Consult a qualified professional for diagnosis and treatment of sleep disorders.