Loud snoring, daytime sleepiness, and waking up gasping for air are common signs of obstructive sleep apnea (OSA). If you notice these symptoms — or your partner does — let your healthcare team know. Your doctor may suggest tests to diagnose obstructive sleep apnea.

Obstructive sleep apnea is a breathing disorder that occurs during sleep. In OSA, the airway gets blocked because the throat muscles relax too much, causing you to stop breathing many times each night. These interruptions in breathing also lower your blood oxygen, which can damage the cardiovascular system (heart and blood vessels) and other parts of your body.

Test results for sleep apnea can help your doctor determine how severe your OSA is and what treatment options may be most effective for you. Early diagnosis and treatment of sleep apnea can help prevent serious health complications. People with sleep apnea have a higher risk of life-threatening complications such as heart disease, stroke, and diabetes, so it’s important to get an accurate diagnosis.

If you’re getting tested for sleep apnea, be sure to discuss your results with your doctor. Here are four tests that help doctors diagnose OSA and what the results might mean.

1. In-Lab Polysomnography

Polysomnography is a sleep study done in a laboratory or sleep center where you’re monitored while you sleep. This is usually done overnight during your normal hours of sleep. If you work at night and sleep during the day, the sleep lab can schedule the test to fit your usual routine.

Polysomnography is considered the most thorough test for sleep apnea. It can also help find other sleep-related health problems, such as narcolepsy. During the test, sensors are placed on your skin to check your breathing and how different parts of your body work while you sleep. Some of the sensors include:

• Electrocardiography — A sensor on your chest checks your heart’s electrical activity and rhythm.
• Electroencephalography — Sensors on your head track brain activity during different stages of sleep, which can indicate sleep disorders.
• Electrooculography — Sensors near your eyes measure eye movements, which help show rapid eye movement (REM) sleep patterns.
• Electromyogram — Sensors on your face and legs measure muscle activity.
• Respiratory inductive plethysmography belt — A belt around your torso checks how hard you are breathing.
• Breathing sensors — Sensors at your nose and mouth measure airflow and breathing patterns.
• Pulse oximeter — A sensor on your finger measures blood oxygen levels and pulse.

Technicians will monitor you with audio and video and look for any problems. If sleep apnea is detected, you may have a split-night study. During the second half of the night, you’ll try continuous positive airway pressure therapy (CPAP), a common treatment for sleep apnea. A CPAP machine provides constant airflow through a mask and can help keep airways open.

Apnea-Hypopnea Index

Polysomnography can measure how many times an hour breathing is interrupted, which is called the apnea-hypopnea index (AHI). To be diagnosed with obstructive sleep apnea, you must have at least five breathing interruptions an hour — either apneas (pauses in breathing for at least 10 seconds) or hypopneas (shallow breathing with low oxygen or brief arousals from sleep).

The AHI shows how serious your obstructive sleep apnea is, based on the number of times your breathing is interrupted, also known as breathing events:

• Mild OSA — Five to 14 events an hour
• Moderate OSA — 15 to 29 events an hour
• Severe OSA — 30 or more events an hour

CPAP therapy may be recommended for all types of sleep apnea, but some people with mild sleep apnea may improve with lifestyle changes such as weight loss, smoking cessation, sleep position adjustments, and better sleep hygiene (routines for better sleeping). Treating nasal allergies can also help with mild OSA.

2. Home Sleep Apnea Tests

If it’s hard for you to do an in-lab sleep study or your healthcare provider thinks you likely have obstructive sleep apnea, they may recommend a home sleep apnea test (HSAT). It may also be easier to get an HSAT if there’s a long wait for polysomnography.

For an HSAT, your doctor will provide a monitoring device to be worn while sleeping at home. The device has sensors that you put on your forehead, nostrils, abdomen, chest, and finger to record:

• Breathing (airflow)
• Respiratory effort
• Oximetry (blood oxygen levels)
• Heart rate or pulse

HSAT is convenient — it takes place at home, where you may sleep better. It’s also less expensive than polysomnography. However, HSAT isn’t as accurate because it uses fewer sensors and you’re not monitored by a technician, who can watch for problems such as a sensor falling off. Also, HSAT sometimes misses mild OSA, and it’s useful only for diagnosing sleep apnea, not other sleep disorders. Your doctor may still recommend a polysomnography to get more detailed information about your breathing and organ function during sleep.

3. Medical History and Physical Examination

Although an accurate OSA diagnosis requires a sleep study, your doctor might start with a physical exam and a review of your medical history. At your appointment, they’ll ask about your sleep habits, symptoms, and overall health history. They may also suggest bringing your bed partner, who might notice loud snoring or gasping that you don’t realize you’re doing.

Your doctor will do a general physical exam and check your neck, throat, and mouth for anything that could block your airway. OSA risk rises with certain features, such as:

• High body weight
• Large waist size
• Large neck size
• Enlarged tongue
• Enlarged tonsils
• Enlarged uvula

For some people, a physical exam may indicate the need for treatment such as surgery to remove blockages, particularly if CPAP therapy hasn’t been effective.

4. STOP Questionnaire

The STOP questionnaire is a simple written test sometimes used to see if someone might have sleep apnea. The questionnaire covers four key signs of sleep apnea — snoring, tiredness, observed breathing pauses (by a bed partner), and high blood pressure. The acronym STOP stands for these signs.

The STOP questionnaire — and the longer STOP-Bang version, which includes body mass index, age, neck size, and gender — are screening tools, not diagnostic tests. The American Academy of Sleep Medicine considers questionnaires and physical exams alone inadequate for diagnosing obstructive sleep apnea. A sleep test is still needed for an official diagnosis, which may lead to treatment that can improve your sleep and quality of life.

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