What Is Hypopnea? How Is Hypopnea Different From Sleep Apnea? Update 04/2024

Sleep apnea, also known as hypopnea, is characterized by episodes of shallow breathing. Sleep apnea is diagnosed when a person has multiple episodes of shallow breathing while sleeping (hypopneas) and complete cessation of breathing (apneas).

An increase in hypopneas during sleep is indicative of a respiratory issue during the night, however there are effective therapies available. Sleep apnea can be more easily identified and treated if the causes, symptoms, and effects of hypopnea are understood.

What Is Hypopnea?

Sleep apnea, both obstructive and central, frequently causes hypopnea as a side effect. In medical terms, hypopnea is defined as 10 seconds or more of shallow breathing in which airflow decreases by at least 30%. During this time, there is also a 3–4% decrease in the amount of oxygen in the blood. The longer a hypopnea episode lasts, the more serious its repercussions.

Apneas, or full cessations of breathing, are another symptom of sleep-related respiratory disorders. It is generally accepted that sleep apnea exists in everyone who has five or more hypopnea or apnea occurrences in an hour while sleeping. A sleep-related breathing issue can raise the risk of heart attack, stroke, cardiovascular disease, diabetes, and liver fibrosis, in addition to causing symptoms including excessive daytime sleepiness and mood disorders if left untreated.

Types of Hypopnea

In general, hypopneas can be divided into three categories. In spite of the fact that all hypopneas involve periods of shallow breathing, the therapeutic options available may vary depending on the underlying reason. It can be challenging for doctors to determine which sort of hypopnea a patient is suffering.

Severe sleep apnea during REM sleep tied to acute CV events

  • Hypopnea is classified as obstructive when it results from a physical obstruction of the airway. These symptoms are typical with obstructive sleep apnea.
  • In the case of central hypopnea, the lack of oxygen is not necessarily the cause of the resulting apnea. Central hypopneas, which are associated with central sleep apnea, can be brought on by issues in the brain stem or by certain drugs.
  • When a person has hypopneas due to a decrease in airflow and a decrease in breathing efforts, they are said to be experiencing mixed hypopneas. An individual being treated for obstructive sleep apnea is at increased risk of developing central sleep apnea, the most prevalent form of which is mixed hypopneas.

How Is Hypopnea Different From Sleep Apnea?

A time of shallow breathing is called hypopnea, whereas a period of no breathing at all is called apnea. Breathing events include both hypopneas and apneas. The term “sleep apnea” is used interchangeably to describe a group of breathing abnormalities that occur during sleep.

When a person has more hypopneas and apneas than is considered healthy, a diagnosis of obstructive or central sleep apnea may be made. The apneas and hypopneas’ origins inform the diagnosis of sleep apnea.

Despite the common perception that apneas are more serious than hypopneas, research suggests that both provide equivalent risks for cardiovascular disease and other health problems. Currently, there is no recognized clinical reason to differentiate between them, according to sleep specialists.

Symptoms of Hypopnea

Sleep hypopneas, like sleep apneas, can bring on the same symptoms.

  • There was a lot of snoring.
  • A severe inability to stay awake during the day.
  • The lack of revitalization upon awakening.
  • Urinary needs in the middle of the night.
  • Dreaming of choking or gasping for air.
  • The dreaded morning headache.
  • Impotence is a sexual disorder.
  • Disruptions in mood.
  • Sticky nose all the time.
  • Putting on weight.

Snoring and gasping for air are only two of the signs of sleep apnea, which can wake up a sleeping companion. There is anecdotal evidence to show that apnea and hypopnea are sometimes not detected until the bed partner of the person with the illness complains about the person’s snoring and demands assessment.

Causes of Hypopnea

When the airway is just partially closed during sleep, we experience obstructive hypopneas. Obesity and hypothyroidism are two disorders that can cause the airway to become narrower and the throat tissue to become more protruding. Another common cause of obstructive hypopnea is a constricted airway brought on by an abnormally shaped jaw or excessively large tonsils. A child’s tonsils or adenoids may be too large, leading to an increase in hypopneas.

Central hypopneas occur in persons with central sleep apnea because the brain temporarily stops sending the body cues to breathe. Damage to the brain stem or the use of opiates are two potential causes of central sleep apnea. Central hypopnea symptoms can also be brought on temporarily by a recent move to a high altitude.
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Hypopnea Risk Factors

Hypopneas are more likely to occur when a person is at risk for some of the following conditions:

  • Obesity.
  • Hypothyroidism.
  • Acromegaly.
  • Disorder characterized by progressive weakness in the muscles.
  • Syndrome of excessive pliability in connective tissue, or Ehlers-Danlos.
  • Origin stories.
  • shortness of the upper or lower jaw.
  • Sex between men.
  • Smoking.

Some of them, including obesity or jaw shape, may be direct causes of hypopneas by restricting airflow. However, there may be more ways in which a person’s sex can put them at risk.

Hypopnea Diagnosis

When a clinician has reason to suspect sleep apnea, they may perform an assessment of risk factors, inquire about the patient’s sleep and medical histories, and conduct a physical examination. While a doctor may suspect an increase in hypopneas, he or she is unlikely to order a sleep study to confirm the suspicion. A sleep study, often called polysomnography, is the most reliable method for identifying sleep apnea.

The results of a sleep study can tell doctors how often you experience apnea or hypopnea, when they occur, and for how long. Medical professionals can learn more about whether a patient has obstructive or central sleep apnea by doing a sleep study.

Although sleep apnea tests at home are becoming more common, the vast majority of sleep studies still take place in clinical settings. Although home sleep apnea tests are convenient, they do not provide as much information as polysomnography. The American Academy of Sleep Medicine recommended that home sleep apnea testing only be used for patients that face an increased risk of moderate to severe obstructive sleep apnea and are free from other health concerns.

Hypopnea Treatment

Doctors commonly treat sleep-disordered breathing disorders, which often include an increased number of hypopneas, with a mix of lifestyle adjustments and continuous positive airway pressure (CPAP) therapy. Lifestyle adjustments may include weight loss, reducing alcohol intake, changing sleeping postures, or ceasing smoking.

In addition to its efficacy in treating OSA, CPAP therapy is widely utilized to treat central sleep apnea. CPAP machines administer pressurized air via a hose and mask during sleep, keeping the airway open and minimizing hypopnea events or preventing them from occurring. Successful treatment with a CPAP machine can have a profound positive influence on quality of life, as well as reduce blood pressure levels and risk of cardiovascular disease.

Oral appliance therapy and surgical correction are further options for treating obstructive sleep apnea. Oral appliances are devices that hold the tongue and jaw forward, opening up the airway. There are a number of surgical procedures that can be used to reduce or eliminate obstructions in the airway.

Hypopnea vs. Sleep Apnea: Similarities and Differences

They share a common symptom: both hypopnea and sleep apnea reduce or disrupt breathing while you sleep. In sleep apnea, breathing temporarily ceases while in hypopnea it is only restricted.

Whether the airway is partially or completely blocked during sleep is the sole real distinction between obstructive sleep apnea and hypopnea. Both apnea and hypopnea episodes may occur simultaneously during the night for patients with OSAHS. This has led some academics to argue that there isn’t enough of a distinction between the two to warrant treating them separately in research.


What is the main difference between apnea and hypopnea?

Both hypopneas and apneas have the same effect on breathing throughout the night, making them quite comparable. Occurring together, sleep apnea and hypopnea are known as obstructive sleep apnea-hypopnea syndrome (OSAHS).
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Hypopnea differs from apnea in that just a portion of normal breathing is disrupted throughout the episode. Technically, it’s not as serious as an apnea because your airway isn’t entirely blocked. During an apnea episode, you stop breathing for 10 seconds or more.

Is hypopnea as bad as apnea?

As a rule of thumb, apneas are more serious than hypopneas. Stopping breathing entirely for 10 seconds or longer is a sign of apneas. However, hypopneas only cause a mild disruption in breathing.

Of course, total cessation of breathing poses more health risks and stresses on the body than any lesser degree of respiration cessation. Both hypopnea and apnea are associated with an increased risk of cardiovascular disease, obesity, and other weight-related health issues, as well as chronic sleep disruptions.

Can hypopnea be cured?

Some hypopnea cases are mild enough that they can be treated successfully with alterations to one’s way of living and, if necessary, medical intervention. Different treatments exist, such as the use of a CPAP machine at night, a change in diet and exercise routine, or even a change in sleeping posture.

It may take years of treatment for severe cases of hypopnea to resolve. Surgery, supplemental oxygen, medicine, and the use of a continuous positive airway pressure (CPAP) machine are all viable options for treating severe hypopnea.

How many hypopneas per hour is normal?

Hypopneas occur when a person stops breathing for 10 seconds or more on multiple occasions during sleep. Adults are regarded to be within the normal range if they experience no more than five hypopnea events each hour. There’s no need to get checked out or treated in this instance. If you’ve had more than five bouts of hypopnea, it’s time to see a doctor.

What is the apnea-hypopnea score?

The severity and prevalence of apnea and hypopnea can be estimated using a rating scale called the apnea-hypopnea index (AHI). A person’s apnea or hypopnea episode frequency is measured in episodes per hour.

Here is how the order pans out:

  • Five or fewer awakenings per hour is considered normal.
  • 5-14 hypopnea bouts per hour is considered mild.
  • If you experience 15-30 hypopnea episodes every hour, your condition is considered moderate.
  • Hyperventilation: more than 30 bouts per hour


A medical ailment, hypopnea causes periods of interrupted breathing while sleeping. In many cases, the illness is persistent, although it can be controlled with medication, surgery, or even just a few little adjustments to one’s daily routine. Individuals diagnosed with hypopnea may benefit from these techniques since they enhance their sleep, and hence their overall quality of life.

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