At a Glance
Hypoventilation occurs when breathing is too slow or shallow to remove enough carbon dioxide from the body. Over time, this can cause carbon dioxide levels to rise and oxygen levels to fall, leading to symptoms such as fatigue, headaches, shortness of breath, and poor sleep. Hypoventilation can result from a variety of medical conditions and, in some cases, may require treatment to prevent serious health complications.
Breathing is something most people rarely think about until it becomes difficult. But when breathing becomes too slow or too shallow, it can affect sleep, energy levels, and overall health. In some cases, these breathing changes occur primarily during sleep, while in others, they can persist throughout the day. Both instances can interfere with daily life.
Below, we explain what hypoventilation is, its causes and symptoms, and the treatments that may help improve breathing and sleep quality.
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What Is Hypoventilation?
Hypoventilation is shallow or slow breathing. As a result, the lungs are unable to remove an adequate amount of carbon dioxide, causing it to build up in the bloodstream. In some cases, oxygen levels and heart rate may also decrease.
Over time, untreated hypoventilation can lead to symptoms such as fatigue, morning headaches, shortness of breath, poor sleep, and difficulty concentrating. In severe cases, it can contribute to serious complications affecting the heart, lungs, and other organs.
Hyperventilation vs. Hypoventilation
Hyperventilation and hypoventilation are opposite breathing patterns. Hyperventilation occurs when a person breathes too quickly or deeply, causing the body to remove too much carbon dioxide. In contrast, hypoventilation occurs when breathing is too slow or too shallow, causing carbon dioxide to build up in the bloodstream.
Causes of Hypoventilation
The causes of hypoventilation vary among its different types. Some forms are linked to obesity or sleep-related breathing disorders, while others result from neurological, muscular, or structural conditions that affect breathing. Identifying the underlying cause of hypoventilation is an important step in determining the most appropriate treatment.
Sleep-Related Hypoventilation
Sleep-related hypoventilation is an umbrella term for a group of disorders involving insufficient breathing during sleep. This disordered breathing can occur when a person is sleeping at any time of day or night, including while they nap.
Sleep-Related Hypoventilation Due to a Medication or Substance
Certain medications and substances, including include muscle relaxants, sleep-inducing drugs, opioid pain medications, alcohol, and some anesthetics, can affect the body’s natural drive to breathe. When these substances make a person’s breathing slow or shallow when they sleep, they may be diagnosed with sleep-related hypoventilation due to a medication or substance.
By definition, sleep-related hypoventilation due to a medication or substance isn't caused by other health conditions. However, people with this condition may also have sleep apnea.
Sleep-Related Hypoventilation Due to a Medical Disorder
When an underlying health issue causes shallow or slow breathing during sleep, it's known as sleep-related hypoventilation due to a medical disorder. Conditions that can cause this include:
- Diseases of the airway or lungs, such as chronic obstructive pulmonary disease (COPD), severe asthma, cystic fibrosis, or interstitial lung disease
- Disorders of the chest wall, such as severe scoliosis
- Pulmonary hypertension (elevated blood pressure in the arteries leading to the lungs)
- Conditions affecting the nervous system, including neuromuscular problems, such as muscular dystrophy, amyotrophic lateral sclerosis (ALS), and spinal cord injuries
Sleep-related hypoventilation due to a medical disorder isn't caused by obesity, genetic mutation, or the use of medications. However, sleep apnea may occur alongside this type of hypoventilation.
Obesity Hypoventilation Syndrome
Obesity hypoventilation syndrome (OHS) occurs in people with obesity. OHS affects breathing when a person is both awake and asleep, but carbon dioxide buildup often gets worse when a person is sleeping. Experts estimate that approximately 0.4% of U.S. adults have OHS. Typically, people develop OHS when they're in their 50s or 60s.
Approximately 90% of people with OHS also have obstructive sleep apnea (OSA), a sleep-related breathing disorder where breathing repeatedly stops or nearly stops due to blockage of the airway. Severe OSA, which involves more than 30 disrupted breathing events per hour, may be a risk factor for developing OHS.
Because of insufficient breathing, people with OHS may sleep poorly at night, especially if they also have OSA. They may exhibit daytime symptoms such as fatigue, headaches, and depression. As OHS worsens, it can affect the heart and lead to high blood pressure.
Congenital Central Hypoventilation Syndrome
Congenital central hypoventilation syndrome (CCHS) is a rare condition, with fewer than 5,000 cases in the United States. The disorder is caused by a gene variant that impairs the nervous system and prevents the body from automatically taking breaths.
The disorder is congenital, which means that people with CCHS are usually born with the condition or develop it shortly after birth. Babies with CCHS take shallow breaths and may have a blue tint to the skin.
Some people with the gene variant don't develop central hypoventilation syndrome until later in childhood or even adulthood. This is known as late-onset central hypoventilation syndrome (LO-CHS).
A person with CCHS may experience decreased body temperature, excessive sweating, and lowered awareness of pain. After adjusting their body position or exercising, they may have a hard time keeping their heart rate and blood pressure at consistent levels.
Less often, a person with CCHS may have digestive issues, eye problems, and learning difficulties. People who develop LO-CHS may have seizures while sleeping, breathing disruptions, and heart failure.
Late-Onset Central Hypoventilation With Hypothalamic Dysfunction
People with late-onset central hypoventilation with hypothalamic dysfunction most often develop the condition after the first two or three years of childhood. People with the disorder experience hypoventilation and two or more of the following symptoms:
- Obesity
- Increase or decrease in hormone levels caused by problems in the hypothalamus, the brain area that regulates growth and other functions
- Abnormal behavior or mood
- Tumors that begin in nerve cells
Unlike CCHS, this disorder isn't caused by a genetic variant. The disorder is also different from OHS because people with late-onset central hypoventilation with hypothalamic dysfunction continue to have breathing problems even after losing weight.
Idiopathic Central Alveolar Hypoventilation
Idiopathic central alveolar hypoventilation is insufficient breathing while asleep that has no clear cause or explanation. This disorder isn't caused by any medical conditions or medication use. This subtype is also not related to obesity or genetics. This disorder is rare and hasn't been well-studied.
Other Symptoms of Hypoventilation
Insufficient breathing, either too slow or too shallow, is the key symptom among all of the different types of hypoventilation. Other symptoms may occur among several kinds of hypoventilation disorders.
- High carbon dioxide levels: Because hypoventilation involves slowed breathing, it can cause high levels of CO2 in the blood.
- Low oxygen levels: A common effect of reduced breathing is insufficient oxygen in the blood.
- Bluish skin: Without enough oxygen in the blood, people with hypoventilation may have skin with a blue tinge.
- Shortness of breath: Some people with hypoventilation disorders experience shortness of breath or painful breathing.
- Obstructive sleep apnea and related symptoms: People with a hypoventilation disorder may also have OSA and experience its symptoms, including daytime sleepiness, loud snoring, and making choking sounds while sleeping.
Diagnosing Hypoventilation
If your healthcare provider suspects a hypoventilation disorder, they may begin by giving you a physical exam and discussing your symptoms. Then they may suggest testing to confirm the diagnosis and rule out other disorders.
Testing usually involves a sleep study, which reveals details about your breathing and the way your body functions when you sleep. A sleep study measures brain activity, breathing patterns, muscle movement, and levels of carbon dioxide and oxygen in the bloodstream.
Your healthcare provider may also request additional testing. When a doctor suspects CCHS or LO-CHS, they may conduct genetic testing. Pulmonary function tests, which measure breathing and lung function when you’re awake, may help the doctor rule out or identify causes of hypoventilation.
Treatment for Hypoventilation
Treatment for hypoventilation often involves treating both the slowed breathing itself and underlying issues that may contribute to the condition. Your healthcare provider can help you determine what treatments are best for your situation.
Positive Airway Pressure (PAP) Therapy
In some cases, your doctor may recommend positive airway pressure (PAP) therapy as part of your treatment plan. PAP therapy requires wearing a mask that provides a stream of pressurized air while you sleep.
PAP therapy is the initial treatment for obesity hypoventilation syndrome. If you have both OHS and OSA, your doctor may advise you to use a continuous positive airway pressure (CPAP) device. CPAP provides a consistent amount of air pressure to prevent the airway from closing.
If you have OHS but not OSA, experts typically recommend bilevel positive airway pressure (BiPAP or BPAP). BiPAP provides a stream of air set to a higher pressure when you inhale and a lower pressure when you exhale.
Ventilators
If you struggle to breathe on your own, a ventilator may help you breathe more regularly. A ventilator is often needed to treat congenital central hypoventilation syndrome during sleep. An estimated 15% of people with CCHS also need to use a ventilator while awake.
Ventilators are also frequently prescribed to help treat late-onset central hypoventilation with hypothalamic dysfunction. However, treatment for LO-CHS usually doesn't require using a ventilator when awake.
Lifestyle and Activity Changes
Depending on the cause of hypoventilation, certain lifestyle changes may improve symptoms. For example, avoiding alcohol and certain medications can support the effectiveness of PAP therapy, while using these substances can make hypoventilation worse.
Specific activities pose a health risk to some groups with a hypoventilation disorder. Experts recommend that people with CCHS avoid swimming and other activities that require holding the breath unless they are closely supervised. This is because CCHS prevents the brain from recognizing when it is necessary to take a breath.
When to See a Doctor
Consider talking with a doctor if you regularly experience shortness of breath, unexplained fatigue, morning headaches, poor sleep quality, difficulty concentrating, or excessive daytime sleepiness. These symptoms may indicate that your body isn't getting enough oxygen or is retaining too much carbon dioxide.
In some cases, hypoventilation occurs primarily during sleep. If you snore frequently, wake up gasping for air, experience pauses in breathing during sleep, or feel excessively tired despite spending enough time in bed, talk with a doctor about whether a sleep study may be appropriate. Early diagnosis and treatment can help prevent complications and improve both breathing and sleep quality.
Frequently Asked Questions
Hypoventilation can lead to a condition called respiratory acidosis, which occurs when the body is unable to remove enough carbon dioxide through breathing. As carbon dioxide builds up in the bloodstream, blood pH becomes more acidic. Mild respiratory acidosis may cause symptoms such as fatigue, headaches, and confusion, while severe cases can be life-threatening. Treating the underlying cause of hypoventilation is an important part of correcting respiratory acidosis.
Anxiety is more commonly associated with hyperventilation, or breathing too quickly and deeply, rather than hypoventilation. During periods of stress or panic, people often breathe rapidly, which can lower carbon dioxide levels in the blood. However, some people with anxiety may feel as though they aren't getting enough air, even when their breathing rate is normal or elevated.
Asthma doesn't typically cause hypoventilation, but severe or poorly controlled asthma can sometimes interfere with normal breathing. During an asthma attack, narrowed airways make it harder to move air in and out of the lungs, which can reduce oxygen levels and increase the work of breathing. In severe cases, breathing may become ineffective enough to cause carbon dioxide levels to rise, leading to hypoventilation.
Medical Disclaimer: This content is for informational purposes and does not constitute medical advice. Please consult a health care provider prior to starting a new treatment or making changes to your treatment plan.
Written by
Audra Sarver, MHS, PA-C, Contributing WriterAudra is a licensed, certified physician assistant and freelance health writer. She has specialized in psychiatry since completing her clinical training in 2018. Her passion for writing was born from the desire to make complex medical information more accessible and understandable to patients and their loved ones. Audra likes to write about all things related to behavioral health and physical wellness.
Reviewed by
Howard J. Hoffman, DDS, Medical ReviewerDr. Howard J. Hoffman is a dentist specializing in dental sleep medicine and the treatment of obstructive sleep apnea and temporomandibular joint (TMJ) disorders. With more than four decades of experience in dentistry and over 25 years focused on sleep apnea treatment, he works with physicians and sleep specialists to help patients manage sleep-disordered breathing using oral appliance therapy.
