Hypopnea is a partial blockage of the airway, and is a feature of a condition called obstructive sleep apnea hypopnea syndrome.

Obstructive sleep apnea hypopnea syndrome is a disease in which the airway is blocked to differing degrees, during sleep.

Apnea is a full obstruction of the airway when a person is asleep, and is another feature of the syndrome, which is more easily referred to as OSAHS.

During episodes of hypopnea, a person experiences a 10-second period when their breathing is reduced by 50 percent or more.

Both hypopnea and sleep apnea are serious medical conditions that can lead to other health complications.

In this article, we look at the effects of hypopnea, its symptoms and causes, and how it can be treated.

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Risk factors associated with hypopnea include obesity and smoking.

OSAHS occurs when there is a narrowing of the airways leading to the lungs during sleep.

It often results when the muscles in the back of the throat relax too much, which causes the airway to narrow and collapse. This prevents normal and regular breathing.

People with sleep apnea or hypopnea often have this disrupted breath for up to 30 seconds at a time.

During this time, the body and brain are not getting enough oxygen, which triggers the brain to wake up and start breathing again.

These periods of wakefulness are so brief that most people are not even aware they are happening.

There are three different types of hypopnea:

  • Central hypopnea: Both airflow and breathing effort are reduced.
  • Obstructive hypopnea: Only the flow of air is reduced, not breathing effort.
  • Mixed hypopnea: There is a mix of both central and obstructive hypopnea episodes.

In central hypopnea, there are none of the signs of obstruction during periods of respiratory effort that are commonly seen during sleep apnea, such as snoring or a blocked airway.

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Excessive daytime sleepiness may be a symptom of hypopnea.

Sleep apnea and hypopnea are very similar. In fact, hypopnea is a type of sleep apnea. The term hypopnea simply means abnormally slow or shallow breathing, while apnea means periods of no breathing.

The main difference between the two is further explained by the degree of blockage in a person’s airway.

In sleep apnea, the airway is completely blocked while in hypopnea, the airway is only partially blocked.

The two conditions tend to occur together with many people who have apnea also having episodes of hypopnea and vice versa.

The Apnea Hypopnea Index (AHI) refers to the amount of apneas or hypopneas a person experiences per hour of sleep. A doctor can use a the AHI to determine the severity of hypopnea, as follows:

  • None or minimal: Less than 5 events per hour.
  • Mild: Between 5 and 15 events per hour.
  • Moderate: Between 15 and 30 events per hour.
  • Severe: More than 30 events per hour.

A doctor may also use the Respiratory Disturbance Index (RDI) to determine the best treatment plan. The RDI includes other breathing irregularities, not just apneas and hypopneas. An individual’s RDI may be higher than their AHI.

The symptoms of hypopnea are similar to those of obstructive sleep apnea and may include:

  • excessive daytime sleepiness
  • loud snoring
  • insomnia
  • difficulty with memory and concentration
  • mood changes
  • fatigue
  • waking at night and feeling short of breath

Many people do not even realize that they have this condition because daytime sleepiness is often attributed to stress, work, or family responsibilities.

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Treatment for hypopnea may include the use of a CPAP machine.

The treatment of hypopnea depends on its severity.

Treatment goals are to remove the obstruction in the airway to make breathing easier and more seamless. This may include the following options:

  • surgical removal of excess tissue
  • use of a device to stabilize and open the airway
  • use of a continuous positive airway pressure (CPAP) machine, during sleep

A CPAP device provides a supply of air to the lungs, usually at nighttime, to prevent breathing from slowing or stopping.

The user wears a mask that is connected to a pump and supplies a flow of air to keep the airways open.


Several lifestyle changes can be helpful in managing or preventing episodes of sleep apnea or hypopnea. They may include:

  • losing weight if necessary
  • quitting smoking
  • quitting drinking alcohol
  • avoiding sleep medications or sedatives

With mild hypopnea, lifestyle changes may be all that is necessary to manage the symptoms.

In cases of severe sleep apnea, these lifestyle changes should be used in combination with other medical treatments, as recommended by the doctor. They can help to reduce symptom severity and the risk of complications.


In most cases of hypopnea, lifestyle changes can prevent symptoms from occurring or getting worse.

This is not true in every case, however, as some risk factors cannot be eliminated completely. It is still important to follow up with a doctor to manage the condition.

Treating the symptoms of sleep apnea or hypopnea can also help to reduce the risk of health complications from this condition.

Obstructive sleep apnea and hypopnea are very serious medical conditions. Every time an episode of apnea or hypopnea occurs, the brain and body tissues are deprived of oxygen.

Without treatment, serious health complications can occur, including:

Daytime sleepiness

Daytime sleepiness or fatigue is not just an annoyance. It can cause serious safety problems, especially when someone is driving or operating machinery.

Daytime sleepiness can also lead to difficulty concentrating or performing at work or school.

Often, people with apnea or hypopnea report falling asleep while at work or while driving.

Heart problems

Falls in the blood oxygen levels that occur when breathing is interrupted can put a strain on the heart or blood vessels.

In the long term, this can lead to heart attack, heart failure, or stroke.

This risk seems to be worse in men with women with sleep apnea not appearing to have the same level of risk for heart disease.

Surgical problems

Surgery, and specifically the use of anesthetic, can be complicated by sleep apnea or hypopnea.

Lying on the back in combination with sedative medication can worsen symptoms, and significantly increase the risk of complications during or after surgery.

People should always tell their doctor about any symptoms of apnea or hypopnea so a diagnosis can be made and any treatment arranged before a surgical procedure.

When to see a doctor

Someone who experiences excessive daytime sleepiness, or who has several of the risk factors associated with sleep apnea, should discuss this with their doctor.

The doctor may recommend further testing or a “watch and wait” approach.

There are several risk factors that are associated with OSAHS, including:

  • Obesity: Many people with sleep apnea are obese or overweight. Carrying extra weight can cause fat to build up in the neck and around the airways, causing the throat to become blocked when someone lies down.
  • Narrow airway: Some people are born with anatomy that is small by nature. Tonsils or structures within the throat called adenoids can also be enlarged, which can narrow the airway.
  • Diabetes: OSAHS is more common in people with diabetes.
  • Gender: Men are more likely to have sleep apnea and hypopnea than women.
  • Family history: People who have a family member who has sleep apnea have a greater chance of developing it themselves.
  • Smoking: Smokers are significantly more likely to develop sleep apnea than nonsmokers.

Sleep apnea itself is not life-threatening. The periods of reduced breathing are brief, and the brain is very good at restarting normal breathing patterns.

However, sleep apnea or hypopnea can cause some serious health problems over time if it is not properly managed.

Anyone who experiences symptoms of hypopnea or sleep apnea should discuss these with their doctor.