What Is Hypopnea, and Is It Serious?

Medically Reviewed By Thomas Johnson, PA-C
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Hypopnea is decreased breathing that occurs during sleep. It lowers the amount of oxygen in your blood and can be serious. Low levels of oxygen in your blood can increase your risk for various health conditions. Read on to learn more about hypopnea including its diagnosis, treatment, and outlook.

What is hypopnea?

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Hypopnea is defined as a decrease in respiratory airflow of 30% or more. It must also cause partial awakening during sleep or a decrease in oxygen saturation of at least 3%. This is according to the American Academy of Sleep Medicine (AASM).

Oxygen saturation refers to the percentage of hemoglobin molecules in your blood that are bound to an oxygen molecule. It is a measure of how well your lungs are functioning.

A quick way of measuring oxygen saturation is to use pulse oximetry. Doctors take this measurement by placing an infrared sensor on your finger.

According to the American Lung Association, a healthy oxygen saturation level is anything higher than 90–92%.

Learn more about oxygen levels.

Hypopnea vs. apnea

Both hypopnea and apnea are conditions in which breathing is decreased during sleep.

The AASM defines apnea as a 90% or more decrease in airflow for at least 10 seconds. Apnea can involve complete pauses in breathing.

Hypopnea is a reduction in airflow rather than a pause. However, the definition of hypopnea is controversial. In fact, researchers may refer to both hypopnea and apnea as “sleep-disordered breathing.”

What causes hypopnea?

Researchers have not identified specific causes of hypopnea separate from those of apnea. As a form of sleep-disordered breathing, hypopnea can be classified as central, obstructive, or both.

Central sleep apnea is much less common than obstructive sleep apnea. In a study of 5,804 adults, researchers found that about 1 in 100 participants had central sleep apnea. By contrast, almost half of participants had obstructive sleep apnea.

Central apnea-hypopnea

Central apnea-hypopnea is caused by improper signaling from the brain. Nerve signals may be disrupted between the brain and the diaphragm, the muscle that allows you to breathe. This disruption of breathing muscle function is a defining characteristic of central apnea-hypopnea.

Risk factors for central apnea-hypopnea include:

Obstructive apnea-hypopnea

Obstructive apnea-hypopnea is caused by relaxation of the upper airway, leading to blocked air flow.

You may be more at risk for obstructive apnea-hypopnea if you:

Females with sleep apnea-hypopnea may be more likely to experience anxiety, depression, or insomnia than males. This is according to the National Heart, Lung, and Blood Institute (NHLBI).

What are the symptoms of hypopnea?

Hypopnea affects your quality of sleep by causing you to partially awaken several times during the night. Symptoms of hypopnea can be related to poor sleep as well as decreased oxygen in your blood. They can be similar to those of sleep apnea and may include:

  • daytime sleepiness
  • morning headaches
  • decreased libido
  • frequent need to urinate at night

A sleep or living partner may also notice symptoms such as:

  • pauses in your breathing
  • snoring
  • gasping for air

When to contact a doctor

Contact your physician if you experience symptoms of hypopnea or a sleep partner notices symptoms such as snoring or gasping.

How is hypopnea diagnosed?

To diagnose hypopnea, your doctor may perform a physical and ask for a complete medical history. This can include any family history of sleep-related respiratory disorders.

Your doctor will assess your general health and identify possible risk factors. They may then order a sleep study or ask you to keep a sleep diary.

Sleep study

Although there are some sleep studies you can do at home, your physician may recommend a study done at a sleep center.

A study at a sleep center may involve taking a polysomnograph test. This test takes different measurements using sensors attached to your body. These sensors will monitor your:

  • breathing effort and rate
  • brain waves, using an EEG
  • heart rate
  • blood oxygen saturation
  • muscle activity

Read more about sleep studies.

The apnea-hypopnea index

The apnea-hypopnea index (AHI) is a way of quantifying apnea and hypopnea events. It can help physicians determine the severity of these events and recommend appropriate treatments.

Your AHI is calculated using a wearable monitor. The monitor records the total number of apnea-hypopnea events you experience during a night of sleep. It then divides this by the number of hours you slept.

Clinicians may classify obstructive sleep apnea using the following criteria:

  • normal: less than 5 events per hour
  • mild: 5–14 events per hour
  • moderate: 15–29 events per hour
  • severe: more than 30 events per hour

How is hypopnea treated?

Treatment for hypopnea will depend on your symptoms and their severity. Treatment options may include:

  • Continuous positive airway pressure (CPAP) therapy: This helps maintain pressure in the trachea during sleep.
  • Oral appliances: These reposition the jaw or tongue to prevent blockage of the airway.
  • eXciteOSA: This is a device approved by the Food and Drug Administration (FDA) to help strengthen the tongue and decrease apnea-hypopnea events.
  • Orofacial therapy: This strengthens the tongue and upper airway muscles.
  • Surgeries: These can include:
    • tonsillectomy or adenoidectomy
    • jaw repositioning surgery
    • surgery to place a device that monitors and controls breathing
    • surgery to remove excess soft tissue obstructing the airway

Read 6 Facts About CPAP Machines.

If you have obesity or are overweight, reaching and maintaining a moderate weight may help alleviate symptoms of hypopnea.

How serious is hypopnea?

Left untreated, sleep apnea and hypopnea can have serious consequences. According to the NHLBI, low oxygen saturation during sleep can increase your risk for certain conditions, including:

Contact your doctor if you have symptoms of hypopnea. They can help you design a treatment plan to manage your hypopnea and lower your risk for more serious conditions.

Frequently asked questions

The following frequently asked questions were reviewed by Thomas Johnson, PA-C.

Does CPAP help with hypopnea?

With correct and consistent use, a CPAP machine can help reduce symptoms of hypopnea.

Contact your physician or a respiratory therapist if your mask fit changes or you experience symptoms while using your CPAP machine. Your settings may need an adjustment.

How many hypopnea episodes per hour is considered normal?

Clinicians consider anything less than 5 apnea-hypopnea episodes per hour to be normal breathing.


Hypopnea and apnea are potentially serious conditions. They disrupt sleep and reduce the amount of oxygen in your blood.

Left untreated, hypopnea and apnea can increase your risk for heart, vascular, and respiratory diseases.

Hypopnea is treatable with a physician’s assistance. Treatment may include lifestyle changes, breathing or oral appliances, and surgery. Correctly following your treatment plan may help to lower your risk for complications.

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Medical Reviewer: Thomas Johnson, PA-C
Last Review Date: 2022 Sep 2
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