Hypopnea vs Apnea: Know the Difference

Key Takeaways

Hypopnea and apnea are symptoms of sleep-related breathing disorders. Hypopnea is a period of shallow breathing, and apnea is a complete stopping of breathing.
A continuous positive airway pressure (CPAP) device is the first-line treatment for moderate to severe sleep apnea-hypopnea syndrome.

Hypopnea and apnea are symptoms of sleep-related breathing disorders that have a negative impact on metabolic health, increase the risk of cardiovascular disease, and result in excessive daytime sleepiness, problems with thinking and concentration, and anxiety and depression.

Please continue reading to learn the differences between apneas versus hypopneas.

What is the difference between hypopnea vs apnea?

Both are symptoms of sleep-disordered breathing, but hypopnea is a period of shallow breathing, while apnea is a complete stopping of breathing.

They commonly occur in people with a condition called obstructive sleep apnea-hypopnea syndrome (OSAHS).

Obstructive hypopnea and apnea develop in people with sleep disorders due to a partial blockage of the upper airway during sleep when the breathing muscles in the throat relax.

This results in an obstruction of airflow in the narrowed airway, which in turn leads to a reduced supply of oxygen to body tissues.

By definition, hypopnea is a drop in airflow by at least 30%, lasting for a minimum of 10 seconds, and leading to a fall in blood oxygen levels by 3% or more, typically followed by arousal from sleep.

By definition, apnea is a complete cessation of airflow for at least 10 seconds. This is evaluated and diagnosed by a sleep study called polysomnography.

What are the different types of sleep apnea disorders?

Sleep apnea patients may be diagnosed with one of the following types of sleep-related breathing disorders.

Obstructive Sleep Apnea

Obstructive sleep apnea syndrome occurs due to a relaxation of the throat muscles during sleep. It is characterized by a complete cessation of airflow for at least 10 seconds, accompanied by a persistent respiratory effort to resume breathing.

Central Sleep Apnea

Central sleep apnea and central hypopnea occur due to an absence of signals from the brain to the breathing muscles. It is characterized by a complete cessation of airflow for at least 10 seconds, accompanied by no respiratory effort.

Mixed Sleep Apnea

Mixed hypopnea apnea begins as central sleep apnea (lasting more than 10 seconds with no breathing effort) and ends as obstructive sleep apnea (persistent breathing effort).

Which is worse: apnea or hypopnea?

Apnea is worse than hypopnea. Apneas are characterized by complete cessation of airflow and stopped breathing. Hypopneas are characterized by a partial reduction in airflow and breathing.

What causes hypopnea?

Anyone can develop sleep apnea syndrome, but some people are at a higher risk. Risk factors for developing sleep apnea-hypopnea syndrome include:

Obesity
Male gender
Older age
Thick neck
Family history of sleep apnea
Chronic nasal congestion
Endocrine disorders, including thyroid disorders
Anatomical defects in head and neck structures
Swollen or enlarged adenoids and tonsils in children
Postmenopausal status
Down syndrome
Smoking

What are apnea hypopnea symptoms?

Symptoms of sleep apnea hypopnea syndrome include loud snoring that disturbs the bed partner, pauses in breathing during sleep, repeated awakenings at night, unrefreshing sleep, feeling unusually tired, trouble falling asleep and staying asleep, problems with thinking and concentration, and excessive sleepiness in the daytime.

Sleep apnea can cause or worsen other health complications such as high blood pressure, arrhythmias (irregular heartbeats), heart failure, stroke, and mood disturbances.

People with sleep disorders are at an increased risk of sleep movement disorders such as restless legs syndrome, circadian disorders of the body’s internal clock, and sleep disorders such as narcolepsy. Learn more about medications for narcolepsy on our blog.

Your healthcare provider will obtain a detailed history of your sleep patterns and daytime functioning and develop a comprehensive treatment plan for sleep apnea that is tailored to your symptoms.

Note: Approximately 80-90% of people with sleep apnea don’t know that they have this potentially dangerous condition. Make an appointment to see your doctor if you have any of the above symptoms.

How do doctors diagnose sleep apnea?

Doctors diagnose sleep apnea-hypopnea syndrome based on the results of a sleep study that is done in a hospital or sleep center and during which they measure the apnea-hypopnea index (AHI). AHI is the number of apnea and hypopnea episodes you experience per hour during sleep.

The higher the AHI, the more severe your sleep apnea. You may also be able to wear a monitor and do a home sleep apnea test.

How many hypopneas per night is normal?

As mentioned, doctors use the apnea-hypopnea index (AHI) to determine the severity of sleep apnea.

An AHI of 30 or above is severe obstructive sleep apnea
An AHI between 15 and 30 apnea events per hour is moderate disease
An AHI between 5 and 15 is mild sleep apnea

Sleep specialists also use the respiratory disturbance index (RDI) to assess sleep apnea-hypopnea syndrome. The RDI is the average number of respiratory disturbances and breathing events (apneas, hypopneas, and nighttime awakenings due to Respiratory Effort Related Arousals) per hour of sleep.

It is worth noting that the severity of the sleep apnea-hypopnea syndrome based on the AHI score does not always correlate to a person’s symptoms. In other words, some people with a mild sleep disorder based on AHI may have severe symptoms such as excessive daytime sleepiness.

Others with severe disease based on AHI may have good sleep quality and get a full night’s sleep and very little daytime sleepiness. Therefore, treatment for sleep apnea is planned on an individual basis, taking into account both the AHI score and the symptoms.

How is obstructive sleep apnea treated?

Lifestyle changes and conservative treatments for mild obstructive sleep apnea include:

Sleeping in a side sleep position rather than on your back.
Losing weight if you are overweight or obese.
Treating nasal congestion and allergies.
Avoiding or reducing alcohol intake.
Avoiding medications that have respiratory depressant effects before bedtime, for example, a sedative medication or other sleep medications.
Getting enough sleep and maintaining good sleep health.
Quitting smoking, if you smoke.

The treatment options for moderate to severe sleep-disordered breathing include:

Using CPAP therapy (continuous positive airway pressure).
Using a dental appliance.
Having surgical correction of an anatomical issue such as a deviated nasal septum by an ear, nose, and throat (ENT) specialist.

Do you need continuous positive airway pressure (CPAP) for hypopnea?

The American Academy of Sleep Medicine recommends a continuous positive airway pressure (CPAP) device as the first-line treatment for moderate to severe sleep apnea-hypopnea syndrome. People with mild sleep apnea may not need CPAP.

However, studies have shown that treating mild sleep apnea with CPAP therapy can improve the quality of life. Can sleep apnea be controlled with medication? Check out our blog to learn more.

Using a CPAP machine helps to eliminate snoring and breathing disturbances, normalizes breathing during sleep, and prevents drops in oxygen saturation.

Keep in mind that to be most effective, the CPAP device must be worn consistently throughout the night.

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