How Is Sleep Apnea Diagnosed? Tests Explained

What is sleep apnea and who should be tested?

Obstructive sleep apnea (OSA) occurs when throat muscles relax during sleep, repeatedly blocking the airway. Each blockage — an apnea — cuts off breathing for seconds to minutes, dropping oxygen levels and fragmenting sleep. The National Heart, Lung, and Blood Institute describes OSA as one of the most common sleep disorders 1Ref 1National Heart, Lung, and Blood Institute (2025).Sleep Apnea - What Is Sleep Apnea?.Obstructive sleep apnea overview including prevalence, symptoms, and general characteristics.

Common symptoms that prompt evaluation: - Loud, persistent snoring (often noticed by a bed partner) - Witnessed gasping or stopping breathing during sleep - Waking with a headache or dry mouth - Excessive daytime sleepiness despite adequate time in bed - Difficulty concentrating during the day - Irritability or mood changes

Not everyone with sleep apnea snores, and not everyone who snores has sleep apnea. Evaluation determines which is which.

What is a home sleep apnea test and how does it work?

A home sleep apnea test (HSAT) is a portable device you use in your own bedroom for one or more nights. It typically records: - Airflow through the nose and mouth - Respiratory effort (chest and abdomen movement) - Blood oxygen saturation via a finger probe - Sometimes heart rate and body position

The recorded data is analyzed — either by software or a sleep medicine clinician — and produces an index of breathing events per hour of sleep. The key metric is the apnea-hypopnea index (AHI) or its home equivalent, the respiratory event index (REI).

The American Academy of Sleep Medicine's 2017 clinical practice guideline supports home sleep testing as the preferred initial diagnostic approach for adults who have a high pre-test probability of moderate-to-severe obstructive sleep apnea and no significant comorbidities that would complicate interpretation 2Ref 2Kapur VK, Auckley DH, Chowdhuri S, et al. (2017).Clinical Practice Guideline for Diagnostic Testing for Adult Obstructive Sleep Apnea: An American Academy of Sleep Medicine Clinical Practice Guideline.AASM guidance supporting home sleep testing as first-line for uncomplicated suspected OSA and indications for in-lab polysomnography3Ref 3American Academy of Sleep Medicine (2017).Clinical Practice Guideline for Diagnostic Testing for Adult Obstructive Sleep Apnea.AASM clinical practice guideline supporting home and in-lab diagnostic pathways for obstructive sleep apnea.

What is polysomnography (an in-lab sleep study)?

An in-lab polysomnogram (PSG) is more comprehensive. You sleep overnight at a sleep center while sensors record: - Brain waves (EEG) — to measure sleep stages - Eye movements (EOG) — REM sleep detection - Muscle activity (EMG) - Airflow, respiratory effort, and oxygen levels - Electrocardiogram (ECG) - Body position - Video recording

PSG captures the full picture of sleep architecture and distinguishes between different types of sleep-disordered breathing that a home test may miss.

In-lab testing is preferred when 2Ref 2Kapur VK, Auckley DH, Chowdhuri S, et al. (2017).Clinical Practice Guideline for Diagnostic Testing for Adult Obstructive Sleep Apnea: An American Academy of Sleep Medicine Clinical Practice Guideline.AASM guidance supporting home sleep testing as first-line for uncomplicated suspected OSA and indications for in-lab polysomnography: - Home testing returns a negative or inconclusive result in someone with strong symptoms - There is concern about central sleep apnea (where the brain rather than the airway causes breathing pauses) - Significant heart disease, pulmonary disease, or neuromuscular conditions are present - Other sleep disorders are suspected alongside OSA — periodic limb movements, parasomnias, narcolepsy

What does the AHI score mean?

The apnea-hypopnea index counts the number of breathing events (apneas plus partial obstructions called hypopneas) per hour of sleep. Standard severity thresholds are:

• Fewer than 5 events per hour: Normal
• 5 to 14: Mild OSA
• 15 to 29: Moderate OSA
• 30 or more: Severe OSA

Severity guides treatment decisions. Mild OSA may be managed with positional therapy or an oral appliance; moderate-to-severe typically requires CPAP (continuous positive airway pressure) therapy, which is the first-line treatment for most people.

Note that the AHI does not capture how much oxygen levels drop during events — some people with relatively low AHI numbers still have significant oxygen desaturation and benefit from treatment.

How do I get tested?

The path to a sleep study runs through a clinician — you cannot order a diagnostic sleep test on your own. The process typically involves:

1. Primary care evaluation: Your clinician reviews symptoms, examines your throat and neck, and assesses risk factors (obesity, neck circumference, blood pressure, family history) 2. Referral or order: Either a home sleep test is ordered directly or you are referred to a sleep medicine specialist 3. Testing: One or more nights at home or in a lab 4. Interpretation and follow-up: A clinician reviews the results and discusses treatment if indicated

A Gale primary care clinician can evaluate your symptoms, determine whether testing is warranted, and order the appropriate study.