At night are supposed to breathe anywhere from 12-20 times per minute. When we breathe less than that rte, our brain does not receive the appropriate amount of oxygen that it needs. These breaths need to be deep and filling our lungs about 6 liters, which is the average volume of air in our lungs following an inhalation.  

When we have a really shallow breathing episode, that is called hypopnea. Any time we breathe slower than what we are supposed to, that is called bradypnea. Both of these put our bodies at risk for receiving a suboptimal amount of oxygen at night. Too many episodes of hypopnea mixed with apnea - episodes of complete cessation of breathing - can lead to a diagnosis of sleep apnea. 

Sleep apnea is a serious sleeping disorder that requires immediate treatment to avoid long-term sequelae. Continue reading to learn more about hypopnea, and determine if you need further work up for your sleep challenges.

What is hypopnea? 

Hypopnea is a common symptom of breathing disorders that happen during sleep. The official definition of hypopnea is 10 or more seconds of shallow breathing in which a person's airflow drops by at least 30%. Blood oxygen levels drop as a result, by at least 3-4%. The longer hypopnea lasts, the more drastic the results. 

Apneas are also common in those with sleep-related breathing disorders. Apneas are episodes of complete cessation of breathing. If someone has five or more episodes during an hour of sleep, they most likely have one of the three types of sleep apnea. Sleep apnea can be difficult to diagnose because individuals experiencing sleep-related breathing disorders often do not know. Their bed partners, however, can tell that their partners stop breathing and then gasp or cough to begin breathing again. Every time your body wakes up to try and regain airflow, it disrupts your sleep, even if it is below your conscious awareness. 

Sleep-related breathing disorders are dangerous because they can have severe consequences. Some of those include metabolic disorders such as diabetes, cardiovascular disease, and liver dysfunction. Sleep is so vital, that consistent interruptions caused by sleep apnea can be detrimental. 

Types of hypopnea 

There are three types of hypopneas. All of them are shallow breathing episodes, but the difference comes in their causes and their required treatments. It can be difficult to distinguish which one you may have unless you consult a sleep expert. 

The first type is obstructive, which means that something is blocking the airway. This includes the tongue, muscles in the back of the throat and enlarged tonsils. When the airway is blocked, then there is not enough space for sufficient air to move through. 

Central hypopnea is an issue with the brain and neurological conduction signaling the lungs to take a long enough breath. Those issues can be caused by brainstem lesions and certain medications that suppress the respiratory drive. 

Mixed hypopnea has features of both where there is a reduction in space for airflow and effort to breathe. These are the most common form that can develop in an individual being treated for obstructive sleep apnea. 

The difference between sleep apnea and hypopnea 

Hypopnea is a shallow breathing episode while sleep apnea is the complete cessation of breathing. Hypopnea is less severe because air is still passing through, where as in sleep apnea, there is no air passing through. 

The combination of both is common in both disease and diagnosis. Regardless of which type you experience more, they both carry the same risk factors. Therefore the diagnosis of sleep apnea is normally given when someone experiences both hypopneas and apneas. 

Hypopnea symptoms

Identifying hypopneas can be difficult because you often are unaware that they are happening. However, here is a list of symptoms that both your bed partner and you need to be on the lookout for:

• Loud snoring 
• Excessive daytime sleepiness
• Feeling unrefreshed upon waking 
• Waking up at night to use the bathroom
• Choking or gasping during sleep
• Morning headaches
• Sexual dysfunction 
• Mood disturbances 
• Chronic nasal congestion 
• Weight gain 

People with sleep-related breathing disorders often interrupt their partner's sleep due to symptoms like snoring and choking. They can be very distressing and disruptive to your bed partner, so they are the best ones to determine if you struggle with sleep apnea. 

Causes of Hypopnea

Obstructive sleep apnea is caused when the airway is partially blocked during sleep. This may be caused by physiologic issues that reduce the space air has to travel in the back of the throat. Conditions like obesity and hypothyroidism increase the risk for these issues. 

Central sleep apnea occurs in those who experience a neurological repression to their respiratory drive. There is no effort to breathe because the signal from the brain to the lungs is absent or interrupted. This is common in those with brain stem issues, neurological immaturity (premies and newborns), or taking medications like opiates which reduce respiratory drive. High altitudes can also cause central hypopnea as your body adjusts to the change of oxygen in the air. 

Risk factors for developing hypopnea are similar to those for develop sleep apnea. They include, but are not limited to: 

• Obesity 
• Hypothyroidism 
• Acromegaly 
• Myotonic dystrophy
• Ehlers-Danlos syndrome 
• Family history
• Short upper or lower jaw
• Male sex 
• Smoking

Diagnosis 

If you or your doctor suspect that you have hypopnea, they will likely order a sleep study, or polysomnography. This is the gold standard for diagnosing many sleep disorders, especially breathing disorders. 

Sleep studies can show professionals hw your breathing changes throughout the night, what state of sleep your brain is in when it does change, and how long they last. All of these parameters are vital for the diagnosis of sleep apnea. 

You can go to a treatment center for a polysomnography, but it's also possible for you to do a home sleep study. That way, you can be in the comfort of your own home while you are having your sleep patterns monitored. Once your results come back, they will be interpreted by a sleep specialist, who will then diagnose you so you can begin treatment. 

Hypopnea treatment

The gold standard for treating sleep-related breathing disorders includes continuous positive airway pressure (CPAP) machine. These machines provide extra pressure through continuous airflow which helps keep your airway open as you exhale. 

Other measures you can take include lifestyle changes, like losing weight, smoking cessation, reduced alcohol use, and abstinence from drugs that can contribute. 

If you think you have hypopnea and would like more information, please click the orange button below to take a free online sleep test and get in contact with one of our sleep health professionals.  

https://www.sleepfoundation.org/sleep-apnea/hypopnea